3749 lines
121 KiB
Plaintext
3749 lines
121 KiB
Plaintext
.\" Copyright (c) 1988, 1989 by Adam de Boor
|
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.\" Copyright (c) 1989 by Berkeley Softworks
|
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.\" Copyright (c) 1988, 1989, 1993
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.\" The Regents of the University of California. All rights reserved.
|
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.\"
|
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.\" This code is derived from software contributed to Berkeley by
|
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.\" Adam de Boor.
|
||
.\"
|
||
.\" Redistribution and use in source and binary forms, with or without
|
||
.\" modification, are permitted provided that the following conditions
|
||
.\" are met:
|
||
.\" 1. Redistributions of source code must retain the above copyright
|
||
.\" notice, this list of conditions and the following disclaimer.
|
||
.\" 2. Redistributions in binary form must reproduce the above copyright
|
||
.\" notice, this list of conditions and the following disclaimer in the
|
||
.\" documentation and/or other materials provided with the distribution.
|
||
.\" 3. All advertising materials mentioning features or use of this software
|
||
.\" must display the following acknowledgement:
|
||
.\" This product includes software developed by the University of
|
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.\" California, Berkeley and its contributors.
|
||
.\" 4. Neither the name of the University nor the names of its contributors
|
||
.\" may be used to endorse or promote products derived from this software
|
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
|
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
|
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
|
||
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
|
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
|
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
|
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" @(#)tutorial.ms 8.1 (Berkeley) 8/18/93
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.\" $FreeBSD$
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.\"
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.so stubs
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.EH 'PSD:12-%''PMake \*- A Tutorial'
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.OH 'PMake \*- A Tutorial''PSD:12-%'
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.\" xH is a macro to provide numbered headers that are automatically stuffed
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.\" into a table-of-contents, properly indented, etc. If the first argument
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.\" is numeric, it is taken as the depth for numbering (as for .NH), else
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.\" the default (1) is assumed.
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.\"
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.\" @P The initial paragraph distance.
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.\" @Q The piece of section number to increment (or 0 if none given)
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.\" @R Section header.
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.\" @S Indent for toc entry
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.\" @T Argument to NH (can't use @Q b/c giving 0 to NH resets the counter)
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.de xH
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.NH \\$1
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\\$2 \\$3 \\$4 \\$5 \\$6 \\$7 \\$8 \\$9
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.nr PD .1v
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.XS \\n%
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.ta 0.6i
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\\*(SN \\$2 \\$3 \\$4 \\$5 \\$6 \\$7 \\$8 \\$9
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.XE
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.nr PD .3v
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..
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.ig
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.\" CW is used to place a string in fixed-width or switch to a
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.\" fixed-width font.
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.\" C is a typewriter font for a laserwriter. Use something else if
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.\" you don't have one...
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.de CW
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.ie !\\n(.$ .ft S
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.el \&\\$3\fS\\$1\fP\\$2
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..
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.\" Anything I put in a display I want to be in fixed-width
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.am DS
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.CW
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..
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.\" The stuff in .No produces a little stop sign in the left margin
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.\" that says NOTE in it. Unfortunately, it does cause a break, but
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.\" hey. Can't have everything. In case you're wondering how I came
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.\" up with such weird commands, they came from running grn on a
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.\" gremlin file...
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.de No
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.br
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.ne 0.5i
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.po -0.5i
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.br
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.mk
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.nr g3 \\n(.f
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.nr g4 \\n(.s
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.ig ft
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.sp -1
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.\" .st cf
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\D's -1u'\D't 5u'
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.sp -1
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\h'50u'\D'l 71u 0u'\D'l 50u 50u'\D'l 0u 71u'\D'l -50u 50u'\D'l -71u 0u'\D'l -50u -50u'\D'l 0u -71u'\D'l 50u -50u'
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.sp -1
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\D't 3u'
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.sp -1
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.sp 7u
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\h'53u'\D'p 14 68u 0u 46u 46u 0u 68u -46u 46u -68u 0u -47u -46u 0u -68u 47u -46u'
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.sp -1
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.ft R
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.ps 6
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.nr g8 \\n(.d
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.ds g9 "NOTE
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.sp 74u
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\h'85u'\v'0.85n'\h-\w\\*(g9u/2u\&\\*(g9
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.sp |\\n(g8u
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.sp 166u
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.ig br
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\D't 3u'\D's -1u'
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.br
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.po
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.rt
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.ft \\n(g3
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.ps \\n(g4
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..
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.de Bp
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.ie !\\n(.$ .IP \(bu 2
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.el .IP "\&" 2
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..
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.po +.3i
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.TL
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PMake \*- A Tutorial
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.AU
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Adam de Boor
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.AI
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Berkeley Softworks
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2150 Shattuck Ave, Penthouse
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Berkeley, CA 94704
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adam@bsw.uu.net
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||
\&...!uunet!bsw!adam
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.FS
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||
Permission to use, copy, modify, and distribute this software and its
|
||
documentation for any purpose and without fee is hereby granted,
|
||
provided that the above copyright notice appears in all copies.
|
||
The University of California, Berkeley Softworks, and Adam de Boor make no
|
||
representations about the suitability of this software for any
|
||
purpose. It is provided "as is" without express or implied warranty.
|
||
.FE
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||
.PP
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||
.xH 1 Introduction
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||
.LP
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||
PMake is a program for creating other programs, or anything else you
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||
can think of for it to do. The basic idea behind PMake is that, for
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||
any given system, be it a program or a document or whatever, there
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||
will be some files that depend on the state of other files (on when
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||
they were last modified). PMake takes these dependencies, which you
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||
must specify, and uses them to build whatever it is you want it to
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||
build.
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||
.LP
|
||
PMake is almost fully-compatible with Make, with which you may already
|
||
be familiar. PMake's most important feature is its ability to run
|
||
several different jobs at once, making the creation of systems
|
||
considerably faster. It also has a great deal more functionality than
|
||
Make. Throughout the text, whenever something is mentioned that is an
|
||
important difference between PMake and Make (i.e. something that will
|
||
cause a makefile to fail if you don't do something about it), or is
|
||
simply important, it will be flagged with a little sign in the left
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||
margin, like this:
|
||
.No
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||
.LP
|
||
This tutorial is divided into three main sections corresponding to basic,
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||
intermediate and advanced PMake usage. If you already know Make well,
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||
you will only need to skim chapter 2 (there are some aspects of
|
||
PMake that I consider basic to its use that didn't exist in Make).
|
||
Things in chapter 3 make life much easier, while those in chapter 4
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||
are strictly for those who know what they are doing. Chapter 5 has
|
||
definitions for the jargon I use and chapter 6 contains possible
|
||
solutions to the problems presented throughout the tutorial.
|
||
.xH 1 The Basics of PMake
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||
.LP
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||
PMake takes as input a file that tells a) which files depend on which
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||
other files to be complete and b) what to do about files that are
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||
``out-of-date.'' This file is known as a ``makefile'' and is usually
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||
.Ix 0 def makefile
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||
kept in the top-most directory of the system to be built. While you
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||
can call the makefile anything you want, PMake will look for
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||
.CW Makefile
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||
and
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||
.CW makefile
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||
(in that order) in the current directory if you don't tell it
|
||
otherwise.
|
||
.Ix 0 def makefile default
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||
To specify a different makefile, use the
|
||
.B \-f
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||
flag (e.g.
|
||
.CW "pmake -f program.mk" ''). ``
|
||
.Ix 0 ref flags -f
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||
.Ix 0 ref makefile other
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||
.LP
|
||
A makefile has four different types of lines in it:
|
||
.RS
|
||
.IP \(bu 2
|
||
File dependency specifications
|
||
.IP \(bu 2
|
||
Creation commands
|
||
.IP \(bu 2
|
||
Variable assignments
|
||
.IP \(bu 2
|
||
Comments, include statements and conditional directives
|
||
.RE
|
||
.LP
|
||
Any line may be continued over multiple lines by ending it with a
|
||
backslash.
|
||
.Ix 0 def "continuation line"
|
||
The backslash, following newline and any initial whitespace
|
||
on the following line are compressed into a single space before the
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||
input line is examined by PMake.
|
||
.xH 2 Dependency Lines
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||
.LP
|
||
As mentioned in the introduction, in any system, there are
|
||
dependencies between the files that make up the system. For instance,
|
||
in a program made up of several C source files and one header file,
|
||
the C files will need to be re-compiled should the header file be
|
||
changed. For a document of several chapters and one macro file, the
|
||
chapters will need to be reprocessed if any of the macros changes.
|
||
.Ix 0 def "dependency"
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||
These are dependencies and are specified by means of dependency lines in
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||
the makefile.
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||
.LP
|
||
.Ix 0 def "dependency line"
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||
On a dependency line, there are targets and sources, separated by a
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||
one- or two-character operator.
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||
The targets ``depend'' on the sources and are usually created from
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||
them.
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||
.Ix 0 def target
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||
.Ix 0 def source
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||
.Ix 0 ref operator
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||
Any number of targets and sources may be specified on a dependency line.
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||
All the targets in the line are made to depend on all the sources.
|
||
Targets and sources need not be actual files, but every source must be
|
||
either an actual file or another target in the makefile.
|
||
If you run out of room, use a backslash at the end of the line to continue onto
|
||
the next one.
|
||
.LP
|
||
Any file may be a target and any file may be a source, but the
|
||
relationship between the two (or however many) is determined by the
|
||
``operator'' that separates them.
|
||
.Ix 0 def operator
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||
Three types of operators exist: one specifies that the datedness of a
|
||
target is determined by the state of its sources, while another
|
||
specifies other files (the sources) that need to be dealt with before
|
||
the target can be re-created. The third operator is very similar to
|
||
the first, with the additional condition that the target is
|
||
out-of-date if it has no sources. These operations are represented by
|
||
the colon, the exclamation point and the double-colon, respectively, and are
|
||
mutually exclusive. Their exact semantics are as follows:
|
||
.IP ":"
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||
.Ix 0 def operator colon
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||
.Ix 0 def :
|
||
If a colon is used, a target on the line is considered to be
|
||
``out-of-date'' (and in need of creation) if
|
||
.RS
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||
.IP \(bu 2
|
||
any of the sources has been modified more recently than the target, or
|
||
.IP \(bu 2
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||
the target doesn't exist.
|
||
.RE
|
||
.Ix 0 def out-of-date
|
||
.IP "\&"
|
||
Under this operation, steps will be taken to re-create the target only
|
||
if it is found to be out-of-date by using these two rules.
|
||
.IP "!"
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||
.Ix 0 def operator force
|
||
.Ix 0 def !
|
||
If an exclamation point is used, the target will always be re-created,
|
||
but this will not happen until all of its sources have been examined
|
||
and re-created, if necessary.
|
||
.IP "::"
|
||
.Ix 0 def operator double-colon
|
||
.Ix 0 def ::
|
||
If a double-colon is used, a target is out-of-date if:
|
||
.RS
|
||
.IP \(bu 2
|
||
any of the sources has been modified more recently than the target, or
|
||
.IP \(bu 2
|
||
the target doesn't exist, or
|
||
.IP \(bu 2
|
||
the target has no sources.
|
||
.RE
|
||
.IP "\&"
|
||
If the target is out-of-date according to these rules, it will be re-created.
|
||
This operator also does something else to the targets, but I'll go
|
||
into that in the next section (``Shell Commands'').
|
||
.LP
|
||
Enough words, now for an example. Take that C program I mentioned
|
||
earlier. Say there are three C files
|
||
.CW a.c , (
|
||
.CW b.c
|
||
and
|
||
.CW c.c )
|
||
each of which
|
||
includes the file
|
||
.CW defs.h .
|
||
The dependencies between the files could then be expressed as follows:
|
||
.DS
|
||
program : a.o b.o c.o
|
||
a.o b.o c.o : defs.h
|
||
a.o : a.c
|
||
b.o : b.c
|
||
c.o : c.c
|
||
.DE
|
||
.LP
|
||
You may be wondering at this point, where
|
||
.CW a.o ,
|
||
.CW b.o
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||
and
|
||
.CW c.o
|
||
came in and why
|
||
.I they
|
||
depend on
|
||
.CW defs.h
|
||
and the C files don't. The reason is quite simple:
|
||
.CW program
|
||
cannot be made by linking together .c files \*- it must be
|
||
made from .o files. Likewise, if you change
|
||
.CW defs.h ,
|
||
it isn't the .c files that need to be re-created, it's the .o files.
|
||
If you think of dependencies in these terms \*- which files (targets)
|
||
need to be created from which files (sources) \*- you should have no problems.
|
||
.LP
|
||
An important thing to notice about the above example, is that all the
|
||
\&.o files appear as targets on more than one line. This is perfectly
|
||
all right: the target is made to depend on all the sources mentioned
|
||
on all the dependency lines. E.g.
|
||
.CW a.o
|
||
depends on both
|
||
.CW defs.h
|
||
and
|
||
.CW a.c .
|
||
.Ix 0 ref dependency
|
||
.No
|
||
.LP
|
||
The order of the dependency lines in the makefile is
|
||
important: the first target on the first dependency line in the
|
||
makefile will be the one that gets made if you don't say otherwise.
|
||
That's why
|
||
.CW program
|
||
comes first in the example makefile, above.
|
||
.LP
|
||
Both targets and sources may contain the standard C-Shell wildcard
|
||
characters
|
||
.CW { , (
|
||
.CW } ,
|
||
.CW * ,
|
||
.CW ? ,
|
||
.CW [ ,
|
||
and
|
||
.CW ] ),
|
||
but the non-curly-brace ones may only appear in the final component
|
||
(the file portion) of the target or source. The characters mean the
|
||
following things:
|
||
.IP \fB{}\fP
|
||
These enclose a comma-separated list of options and cause the pattern
|
||
to be expanded once for each element of the list. Each expansion
|
||
contains a different element. For example,
|
||
.CW src/{whiffle,beep,fish}.c
|
||
expands to the three words
|
||
.CW src/whiffle.c ,
|
||
.CW src/beep.c ,
|
||
and
|
||
.CW src/fish.c .
|
||
These braces may be nested and, unlike the other wildcard characters,
|
||
the resulting words need not be actual files. All other wildcard
|
||
characters are expanded using the files that exist when PMake is
|
||
started.
|
||
.IP \fB*\fP
|
||
This matches zero or more characters of any sort.
|
||
.CW src/*.c
|
||
will expand to the same three words as above as long as
|
||
.CW src
|
||
contains those three files (and no other files that end in
|
||
.CW .c ).
|
||
.IP \fB?\fP
|
||
Matches any single character.
|
||
.IP \fB[]\fP
|
||
This is known as a character class and contains either a list of
|
||
single characters, or a series of character ranges
|
||
.CW a-z , (
|
||
for example means all characters between a and z), or both. It matches
|
||
any single character contained in the list. E.g.
|
||
.CW [A-Za-z]
|
||
will match all letters, while
|
||
.CW [0123456789]
|
||
will match all numbers.
|
||
.xH 2 Shell Commands
|
||
.LP
|
||
``Isn't that nice,'' you say to yourself, ``but how are files
|
||
actually `re-created,' as he likes to spell it?''
|
||
The re-creation is accomplished by commands you place in the makefile.
|
||
These commands are passed to the Bourne shell (better known as
|
||
``/bin/sh'') to be executed and are
|
||
.Ix 0 ref shell
|
||
.Ix 0 ref re-creation
|
||
.Ix 0 ref update
|
||
expected to do what's necessary to update the target file (PMake
|
||
doesn't actually check to see if the target was created. It just
|
||
assumes it's there).
|
||
.Ix 0 ref target
|
||
.LP
|
||
Shell commands in a makefile look a lot like shell commands you would
|
||
type at a terminal, with one important exception: each command in a
|
||
makefile
|
||
.I must
|
||
be preceded by at least one tab.
|
||
.LP
|
||
Each target has associated with it a shell script made up of
|
||
one or more of these shell commands. The creation script for a target
|
||
should immediately follow the dependency line for that target. While
|
||
any given target may appear on more than one dependency line, only one
|
||
of these dependency lines may be followed by a creation script, unless
|
||
the `::' operator was used on the dependency line.
|
||
.Ix 0 ref operator double-colon
|
||
.Ix 0 ref ::
|
||
.No
|
||
.LP
|
||
If the double-colon was used, each dependency line for the target
|
||
may be followed by a shell script. That script will only be executed
|
||
if the target on the associated dependency line is out-of-date with
|
||
respect to the sources on that line, according to the rules I gave
|
||
earlier.
|
||
I'll give you a good example of this later on.
|
||
.LP
|
||
To expand on the earlier makefile, you might add commands as follows:
|
||
.DS
|
||
program : a.o b.o c.o
|
||
cc a.o b.o c.o \-o program
|
||
a.o b.o c.o : defs.h
|
||
a.o : a.c
|
||
cc \-c a.c
|
||
b.o : b.c
|
||
cc \-c b.c
|
||
c.o : c.c
|
||
cc \-c c.c
|
||
.DE
|
||
.LP
|
||
Something you should remember when writing a makefile is, the
|
||
commands will be executed if the
|
||
.I target
|
||
on the dependency line is out-of-date, not the sources.
|
||
.Ix 0 ref target
|
||
.Ix 0 ref source
|
||
.Ix 0 ref out-of-date
|
||
In this example, the command
|
||
.CW "cc \-c a.c" '' ``
|
||
will be executed if
|
||
.CW a.o
|
||
is out-of-date. Because of the `:' operator,
|
||
.Ix 0 ref :
|
||
.Ix 0 ref operator colon
|
||
this means that should
|
||
.CW a.c
|
||
.I or
|
||
.CW defs.h
|
||
have been modified more recently than
|
||
.CW a.o ,
|
||
the command will be executed
|
||
.CW a.o "\&" (
|
||
will be considered out-of-date).
|
||
.Ix 0 ref out-of-date
|
||
.LP
|
||
Remember how I said the only difference between a makefile shell
|
||
command and a regular shell command was the leading tab? I lied. There
|
||
is another way in which makefile commands differ from regular ones.
|
||
The first two characters after the initial whitespace are treated
|
||
specially.
|
||
If they are any combination of `@' and `\-', they cause PMake to do
|
||
different things.
|
||
.LP
|
||
In most cases, shell commands are printed before they're
|
||
actually executed. This is to keep you informed of what's going on. If
|
||
an `@' appears, however, this echoing is suppressed. In the case of an
|
||
.CW echo
|
||
command, say
|
||
.CW "echo Linking index" ,'' ``
|
||
it would be
|
||
rather silly to see
|
||
.DS
|
||
echo Linking index
|
||
Linking index
|
||
.DE
|
||
.LP
|
||
so PMake allows you to place an `@' before the command
|
||
.CW "@echo Linking index" '') (``
|
||
to prevent the command from being printed.
|
||
.LP
|
||
The other special character is the `\-'. In case you didn't know,
|
||
shell commands finish with a certain ``exit status.'' This status is
|
||
made available by the operating system to whatever program invoked the
|
||
command. Normally this status will be 0 if everything went ok and
|
||
non-zero if something went wrong. For this reason, PMake will consider
|
||
an error to have occurred if one of the shells it invokes returns a non-zero
|
||
status. When it detects an error, PMake's usual action is to abort
|
||
whatever it's doing and exit with a non-zero status itself (any other
|
||
targets that were being created will continue being made, but nothing
|
||
new will be started. PMake will exit after the last job finishes).
|
||
This behavior can be altered, however, by placing a `\-' at the front
|
||
of a command
|
||
.CW "\-mv index index.old" ''), (``
|
||
certain command-line arguments,
|
||
or doing other things, to be detailed later. In such
|
||
a case, the non-zero status is simply ignored and PMake keeps chugging
|
||
along.
|
||
.No
|
||
.LP
|
||
Because all the commands are given to a single shell to execute, such
|
||
things as setting shell variables, changing directories, etc., last
|
||
beyond the command in which they are found. This also allows shell
|
||
compound commands (like
|
||
.CW for
|
||
loops) to be entered in a natural manner.
|
||
Since this could cause problems for some makefiles that depend on
|
||
each command being executed by a single shell, PMake has a
|
||
.B \-B
|
||
.Ix 0 ref compatibility
|
||
.Ix 0 ref flags -B
|
||
flag (it stands for backwards-compatible) that forces each command to
|
||
be given to a separate shell. It also does several other things, all
|
||
of which I discourage since they are now old-fashioned.\|.\|.\|.
|
||
.No
|
||
.LP
|
||
A target's shell script is fed to the shell on its (the shell's) input stream.
|
||
This means that any commands, such as
|
||
.CW ci
|
||
that need to get input from the terminal won't work right \*- they'll
|
||
get the shell's input, something they probably won't find to their
|
||
liking. A simple way around this is to give a command like this:
|
||
.DS
|
||
ci $(SRCS) < /dev/tty
|
||
.DE
|
||
This would force the program's input to come from the terminal. If you
|
||
can't do this for some reason, your only other alternative is to use
|
||
PMake in its fullest compatibility mode. See
|
||
.B Compatibility
|
||
in chapter 4.
|
||
.Ix 0 ref compatibility
|
||
.LP
|
||
.xH 2 Variables
|
||
.LP
|
||
PMake, like Make before it, has the ability to save text in variables
|
||
to be recalled later at your convenience. Variables in PMake are used
|
||
much like variables in the shell and, by tradition, consist of
|
||
all upper-case letters (you don't
|
||
.I have
|
||
to use all upper-case letters.
|
||
In fact there's nothing to stop you from calling a variable
|
||
.CW @^&$%$ .
|
||
Just tradition). Variables are assigned-to using lines of the form
|
||
.Ix 0 def variable assignment
|
||
.DS
|
||
VARIABLE = value
|
||
.DE
|
||
.Ix 0 def variable assignment
|
||
appended-to by
|
||
.DS
|
||
VARIABLE += value
|
||
.DE
|
||
.Ix 0 def variable appending
|
||
.Ix 0 def variable assignment appended
|
||
.Ix 0 def +=
|
||
conditionally assigned-to (if the variable isn't already defined) by
|
||
.DS
|
||
VARIABLE ?= value
|
||
.DE
|
||
.Ix 0 def variable assignment conditional
|
||
.Ix 0 def ?=
|
||
and assigned-to with expansion (i.e. the value is expanded (see below)
|
||
before being assigned to the variable\*-useful for placing a value at
|
||
the beginning of a variable, or other things) by
|
||
.DS
|
||
VARIABLE := value
|
||
.DE
|
||
.Ix 0 def variable assignment expanded
|
||
.Ix 0 def :=
|
||
.LP
|
||
Any whitespace before
|
||
.I value
|
||
is stripped off. When appending, a space is placed between the old
|
||
value and the stuff being appended.
|
||
.LP
|
||
The final way a variable may be assigned to is using
|
||
.DS
|
||
VARIABLE != shell-command
|
||
.DE
|
||
.Ix 0 def variable assignment shell-output
|
||
.Ix 0 def !=
|
||
In this case,
|
||
.I shell-command
|
||
has all its variables expanded (see below) and is passed off to a
|
||
shell to execute. The output of the shell is then placed in the
|
||
variable. Any newlines (other than the final one) are replaced by
|
||
spaces before the assignment is made. This is typically used to find
|
||
the current directory via a line like:
|
||
.DS
|
||
CWD != pwd
|
||
.DE
|
||
.LP
|
||
.B Note:
|
||
this is intended to be used to execute commands that produce small amounts
|
||
of output (e.g. ``pwd''). The implementation is less than intelligent and will
|
||
likely freeze if you execute something that produces thousands of
|
||
bytes of output (8 Kb is the limit on many UNIX systems).
|
||
.LP
|
||
The value of a variable may be retrieved by enclosing the variable
|
||
name in parentheses or curly braces and preceeding the whole thing
|
||
with a dollar sign.
|
||
.LP
|
||
For example, to set the variable CFLAGS to the string
|
||
.CW "\-I/sprite/src/lib/libc \-O" ,'' ``
|
||
you would place a line
|
||
.DS
|
||
CFLAGS = \-I/sprite/src/lib/libc \-O
|
||
.DE
|
||
in the makefile and use the word
|
||
.CW "$(CFLAGS)"
|
||
wherever you would like the string
|
||
.CW "\-I/sprite/src/lib/libc \-O"
|
||
to appear. This is called variable expansion.
|
||
.Ix 0 def variable expansion
|
||
.No
|
||
.LP
|
||
Unlike Make, PMake will not expand a variable unless it knows
|
||
the variable exists. E.g. if you have a
|
||
.CW "${i}"
|
||
in a shell command and you have not assigned a value to the variable
|
||
.CW i
|
||
(the empty string is considered a value, by the way), where Make would have
|
||
substituted the empty string, PMake will leave the
|
||
.CW "${i}"
|
||
alone.
|
||
To keep PMake from substituting for a variable it knows, precede the
|
||
dollar sign with another dollar sign.
|
||
(e.g. to pass
|
||
.CW "${HOME}"
|
||
to the shell, use
|
||
.CW "$${HOME}" ).
|
||
This causes PMake, in effect, to expand the
|
||
.CW $
|
||
macro, which expands to a single
|
||
.CW $ .
|
||
For compatibility, Make's style of variable expansion will be used
|
||
if you invoke PMake with any of the compatibility flags (\c
|
||
.B \-V ,
|
||
.B \-B
|
||
or
|
||
.B \-M .
|
||
The
|
||
.B \-V
|
||
flag alters just the variable expansion).
|
||
.Ix 0 ref flags -V
|
||
.Ix 0 ref flags -B
|
||
.Ix 0 ref flags -M
|
||
.Ix 0 ref compatibility
|
||
.LP
|
||
.Ix 0 ref variable expansion
|
||
There are two different times at which variable expansion occurs:
|
||
When parsing a dependency line, the expansion occurs immediately
|
||
upon reading the line. If any variable used on a dependency line is
|
||
undefined, PMake will print a message and exit.
|
||
Variables in shell commands are expanded when the command is
|
||
executed.
|
||
Variables used inside another variable are expanded whenever the outer
|
||
variable is expanded (the expansion of an inner variable has no effect
|
||
on the outer variable. I.e. if the outer variable is used on a dependency
|
||
line and in a shell command, and the inner variable changes value
|
||
between when the dependency line is read and the shell command is
|
||
executed, two different values will be substituted for the outer
|
||
variable).
|
||
.Ix 0 def variable types
|
||
.LP
|
||
Variables come in four flavors, though they are all expanded the same
|
||
and all look about the same. They are (in order of expanding scope):
|
||
.RS
|
||
.IP \(bu 2
|
||
Local variables.
|
||
.Ix 0 ref variable local
|
||
.IP \(bu 2
|
||
Command-line variables.
|
||
.Ix 0 ref variable command-line
|
||
.IP \(bu 2
|
||
Global variables.
|
||
.Ix 0 ref variable global
|
||
.IP \(bu 2
|
||
Environment variables.
|
||
.Ix 0 ref variable environment
|
||
.RE
|
||
.LP
|
||
The classification of variables doesn't matter much, except that the
|
||
classes are searched from the top (local) to the bottom (environment)
|
||
when looking up a variable. The first one found wins.
|
||
.xH 3 Local Variables
|
||
.LP
|
||
.Ix 0 def variable local
|
||
Each target can have as many as seven local variables. These are
|
||
variables that are only ``visible'' within that target's shell script
|
||
and contain such things as the target's name, all of its sources (from
|
||
all its dependency lines), those sources that were out-of-date, etc.
|
||
Four local variables are defined for all targets. They are:
|
||
.RS
|
||
.IP ".TARGET"
|
||
.Ix 0 def variable local .TARGET
|
||
.Ix 0 def .TARGET
|
||
The name of the target.
|
||
.IP ".OODATE"
|
||
.Ix 0 def variable local .OODATE
|
||
.Ix 0 def .OODATE
|
||
The list of the sources for the target that were considered out-of-date.
|
||
The order in the list is not guaranteed to be the same as the order in
|
||
which the dependencies were given.
|
||
.IP ".ALLSRC"
|
||
.Ix 0 def variable local .ALLSRC
|
||
.Ix 0 def .ALLSRC
|
||
The list of all sources for this target in the order in which they
|
||
were given.
|
||
.IP ".PREFIX"
|
||
.Ix 0 def variable local .PREFIX
|
||
.Ix 0 def .PREFIX
|
||
The target without its suffix and without any leading path. E.g. for
|
||
the target
|
||
.CW ../../lib/compat/fsRead.c ,
|
||
this variable would contain
|
||
.CW fsRead .
|
||
.RE
|
||
.LP
|
||
Three other local variables are set only for certain targets under
|
||
special circumstances. These are the ``.IMPSRC,''
|
||
.Ix 0 ref variable local .IMPSRC
|
||
.Ix 0 ref .IMPSRC
|
||
``.ARCHIVE,''
|
||
.Ix 0 ref variable local .ARCHIVE
|
||
.Ix 0 ref .ARCHIVE
|
||
and ``.MEMBER''
|
||
.Ix 0 ref variable local .MEMBER
|
||
.Ix 0 ref .MEMBER
|
||
variables. When they are set and how they are used is described later.
|
||
.LP
|
||
Four of these variables may be used in sources as well as in shell
|
||
scripts.
|
||
.Ix 0 def "dynamic source"
|
||
.Ix 0 def source dynamic
|
||
These are ``.TARGET'', ``.PREFIX'', ``.ARCHIVE'' and ``.MEMBER''. The
|
||
variables in the sources are expanded once for each target on the
|
||
dependency line, providing what is known as a ``dynamic source,''
|
||
.Rd 0
|
||
allowing you to specify several dependency lines at once. For example,
|
||
.DS
|
||
$(OBJS) : $(.PREFIX).c
|
||
.DE
|
||
will create a dependency between each object file and its
|
||
corresponding C source file.
|
||
.xH 3 Command-line Variables
|
||
.LP
|
||
.Ix 0 def variable command-line
|
||
Command-line variables are set when PMake is first invoked by giving a
|
||
variable assignment as one of the arguments. For example,
|
||
.DS
|
||
pmake "CFLAGS = -I/sprite/src/lib/libc -O"
|
||
.DE
|
||
would make
|
||
.CW CFLAGS
|
||
be a command-line variable with the given value. Any assignments to
|
||
.CW CFLAGS
|
||
in the makefile will have no effect, because once it
|
||
is set, there is (almost) nothing you can do to change a command-line
|
||
variable (the search order, you see). Command-line variables may be
|
||
set using any of the four assignment operators, though only
|
||
.CW =
|
||
and
|
||
.CW ?=
|
||
behave as you would expect them to, mostly because assignments to
|
||
command-line variables are performed before the makefile is read, thus
|
||
the values set in the makefile are unavailable at the time.
|
||
.CW +=
|
||
.Ix 0 ref +=
|
||
.Ix 0 ref variable assignment appended
|
||
is the same as
|
||
.CW = ,
|
||
because the old value of the variable is sought only in the scope in
|
||
which the assignment is taking place (for reasons of efficiency that I
|
||
won't get into here).
|
||
.CW :=
|
||
and
|
||
.CW ?=
|
||
.Ix 0 ref :=
|
||
.Ix 0 ref ?=
|
||
.Ix 0 ref variable assignment expanded
|
||
.Ix 0 ref variable assignment conditional
|
||
will work if the only variables used are in the environment.
|
||
.CW !=
|
||
is sort of pointless to use from the command line, since the same
|
||
effect can no doubt be accomplished using the shell's own command
|
||
substitution mechanisms (backquotes and all that).
|
||
.xH 3 Global Variables
|
||
.LP
|
||
.Ix 0 def variable global
|
||
Global variables are those set or appended-to in the makefile.
|
||
There are two classes of global variables: those you set and those PMake sets.
|
||
As I said before, the ones you set can have any name you want them to have,
|
||
except they may not contain a colon or an exclamation point.
|
||
The variables PMake sets (almost) always begin with a
|
||
period and always contain upper-case letters, only. The variables are
|
||
as follows:
|
||
.RS
|
||
.IP .PMAKE
|
||
.Ix 0 def variable global .PMAKE
|
||
.Ix 0 def .PMAKE
|
||
.Ix 0 def variable global MAKE
|
||
.Ix 0 def MAKE
|
||
The name by which PMake was invoked is stored in this variable. For
|
||
compatibility, the name is also stored in the MAKE variable.
|
||
.IP .MAKEFLAGS
|
||
.Ix 0 def variable global .MAKEFLAGS
|
||
.Ix 0 def .MAKEFLAGS variable
|
||
.Ix 0 def variable global MFLAGS
|
||
.Ix 0 def MFLAGS
|
||
All the relevant flags with which PMake was invoked. This does not
|
||
include such things as
|
||
.B \-f
|
||
or variable assignments. Again for compatibility, this value is stored
|
||
in the MFLAGS variable as well.
|
||
.RE
|
||
.LP
|
||
Two other variables, ``.INCLUDES'' and ``.LIBS,'' are covered in the
|
||
section on special targets in chapter 3.
|
||
.Ix 0 ref variable global .INCLUDES
|
||
.Ix 0 ref variable global .LIBS
|
||
.LP
|
||
Global variables may be deleted using lines of the form:
|
||
.Ix 0 def #undef
|
||
.Ix 0 def variable deletion
|
||
.DS
|
||
#undef \fIvariable\fP
|
||
.DE
|
||
The
|
||
.CW # ' `
|
||
must be the first character on the line. Note that this may only be
|
||
done on global variables.
|
||
.xH 3 Environment Variables
|
||
.LP
|
||
.Ix 0 def variable environment
|
||
Environment variables are passed by the shell that invoked PMake and
|
||
are given by PMake to each shell it invokes. They are expanded like
|
||
any other variable, but they cannot be altered in any way.
|
||
.LP
|
||
One special environment variable,
|
||
.CW PMAKE ,
|
||
.Ix 0 def variable environment PMAKE
|
||
is examined by PMake for command-line flags, variable assignments,
|
||
etc., it should always use. This variable is examined before the
|
||
actual arguments to PMake are. In addition, all flags given to PMake,
|
||
either through the
|
||
.CW PMAKE
|
||
variable or on the command line, are placed in this environment
|
||
variable and exported to each shell PMake executes. Thus recursive
|
||
invocations of PMake automatically receive the same flags as the
|
||
top-most one.
|
||
.LP
|
||
Using all these variables, you can compress the sample makefile even more:
|
||
.DS
|
||
OBJS = a.o b.o c.o
|
||
program : $(OBJS)
|
||
cc $(.ALLSRC) \-o $(.TARGET)
|
||
$(OBJS) : defs.h
|
||
a.o : a.c
|
||
cc \-c a.c
|
||
b.o : b.c
|
||
cc \-c b.c
|
||
c.o : c.c
|
||
cc \-c c.c
|
||
.DE
|
||
.Ix 0 ref variable local .ALLSRC
|
||
.Ix 0 ref .ALLSRC
|
||
.Ix 0 ref variable local .TARGET
|
||
.Ix 0 ref .TARGET
|
||
.Rd 3
|
||
.xH 2 Comments
|
||
.LP
|
||
.Ix 0 def comments
|
||
Comments in a makefile start with a `#' character and extend to the
|
||
end of the line. They may appear
|
||
anywhere you want them, except in a shell command (though the shell
|
||
will treat it as a comment, too). If, for some reason, you need to use the `#'
|
||
in a variable or on a dependency line, put a backslash in front of it.
|
||
PMake will compress the two into a single `#' (Note: this isn't true
|
||
if PMake is operating in full-compatibility mode).
|
||
.Ix 0 ref flags -M
|
||
.Ix 0 ref compatibility
|
||
.xH 2 Parallelism
|
||
.No
|
||
.LP
|
||
PMake was specifically designed to re-create several targets at once,
|
||
when possible. You do not have to do anything special to cause this to
|
||
happen (unless PMake was configured to not act in parallel, in which
|
||
case you will have to make use of the
|
||
.B \-L
|
||
and
|
||
.B \-J
|
||
flags (see below)),
|
||
.Ix 0 ref flags -L
|
||
.Ix 0 ref flags -J
|
||
but you do have to be careful at times.
|
||
.LP
|
||
There are several problems you are likely to encounter. One is
|
||
that some makefiles (and programs) are written in such a way that it is
|
||
impossible for two targets to be made at once. The program
|
||
.CW xstr ,
|
||
for example,
|
||
always modifies the files
|
||
.CW strings
|
||
and
|
||
.CW x.c .
|
||
There is no way to change it. Thus you cannot run two of them at once
|
||
without something being trashed. Similarly, if you have commands
|
||
in the makefile that always send output to the same file, you will not
|
||
be able to make more than one target at once unless you change the
|
||
file you use. You can, for instance, add a
|
||
.CW $$$$
|
||
to the end of the file name to tack on the process ID of the shell
|
||
executing the command (each
|
||
.CW $$
|
||
expands to a single
|
||
.CW $ ,
|
||
thus giving you the shell variable
|
||
.CW $$ ).
|
||
Since only one shell is used for all the
|
||
commands, you'll get the same file name for each command in the
|
||
script.
|
||
.LP
|
||
The other problem comes from improperly-specified dependencies that
|
||
worked in Make because of its sequential, depth-first way of examining
|
||
them. While I don't want to go into depth on how PMake
|
||
works (look in chapter 4 if you're interested), I will warn you that
|
||
files in two different ``levels'' of the dependency tree may be
|
||
examined in a different order in PMake than they were in Make. For
|
||
example, given the makefile
|
||
.DS
|
||
a : b c
|
||
b : d
|
||
.DE
|
||
PMake will examine the targets in the order
|
||
.CW c ,
|
||
.CW d ,
|
||
.CW b ,
|
||
.CW a .
|
||
If the makefile's author expected PMake to abort before making
|
||
.CW c
|
||
if an error occurred while making
|
||
.CW b ,
|
||
or if
|
||
.CW b
|
||
needed to exist before
|
||
.CW c
|
||
was made,
|
||
s/he will be sorely disappointed. The dependencies are
|
||
incomplete, since in both these cases,
|
||
.CW c
|
||
would depend on
|
||
.CW b .
|
||
So watch out.
|
||
.LP
|
||
Another problem you may face is that, while PMake is set up to handle the
|
||
output from multiple jobs in a graceful fashion, the same is not so for input.
|
||
It has no way to regulate input to different jobs,
|
||
so if you use the redirection from
|
||
.CW /dev/tty
|
||
I mentioned earlier, you must be careful not to run two of the jobs at once.
|
||
.xH 2 Writing and Debugging a Makefile
|
||
.LP
|
||
Now you know most of what's in a makefile, what do you do next? There
|
||
are two choices: (1) use one of the uncommonly-available makefile
|
||
generators or (2) write your own makefile (I leave out the third choice of
|
||
ignoring PMake and doing everything by hand as being beyond the bounds
|
||
of common sense).
|
||
.LP
|
||
When faced with the writing of a makefile, it is usually best to start
|
||
from first principles: just what
|
||
.I are
|
||
you trying to do? What do you want the makefile finally to produce?
|
||
.LP
|
||
To begin with a somewhat traditional example, let's say you need to
|
||
write a makefile to create a program,
|
||
.CW expr ,
|
||
that takes standard infix expressions and converts them to prefix form (for
|
||
no readily apparent reason). You've got three source files, in C, that
|
||
make up the program:
|
||
.CW main.c ,
|
||
.CW parse.c ,
|
||
and
|
||
.CW output.c .
|
||
Harking back to my pithy advice about dependency lines, you write the
|
||
first line of the file:
|
||
.DS
|
||
expr : main.o parse.o output.o
|
||
.DE
|
||
because you remember
|
||
.CW expr
|
||
is made from
|
||
.CW .o
|
||
files, not
|
||
.CW .c
|
||
files. Similarly for the
|
||
.CW .o
|
||
files you produce the lines:
|
||
.DS
|
||
main.o : main.c
|
||
parse.o : parse.c
|
||
output.o : output.c
|
||
main.o parse.o output.o : defs.h
|
||
.DE
|
||
.LP
|
||
Great. You've now got the dependencies specified. What you need now is
|
||
commands. These commands, remember, must produce the target on the
|
||
dependency line, usually by using the sources you've listed.
|
||
You remember about local variables? Good, so it should come
|
||
to you as no surprise when you write
|
||
.DS
|
||
expr : main.o parse.o output.o
|
||
cc -o $(.TARGET) $(.ALLSRC)
|
||
.DE
|
||
Why use the variables? If your program grows to produce postfix
|
||
expressions too (which, of course, requires a name change or two), it
|
||
is one fewer place you have to change the file. You cannot do this for
|
||
the object files, however, because they depend on their corresponding
|
||
source files
|
||
.I and
|
||
.CW defs.h ,
|
||
thus if you said
|
||
.DS
|
||
cc -c $(.ALLSRC)
|
||
.DE
|
||
you'd get (for
|
||
.CW main.o ):
|
||
.DS
|
||
cc -c main.c defs.h
|
||
.DE
|
||
which is wrong. So you round out the makefile with these lines:
|
||
.DS
|
||
main.o : main.c
|
||
cc -c main.c
|
||
parse.o : parse.c
|
||
cc -c parse.c
|
||
output.o : output.c
|
||
cc -c output.c
|
||
.DE
|
||
.LP
|
||
The makefile is now complete and will, in fact, create the program you
|
||
want it to without unnecessary compilations or excessive typing on
|
||
your part. There are two things wrong with it, however (aside from it
|
||
being altogether too long, something I'll address in chapter 3):
|
||
.IP 1)
|
||
The string
|
||
.CW "main.o parse.o output.o" '' ``
|
||
is repeated twice, necessitating two changes when you add postfix
|
||
(you were planning on that, weren't you?). This is in direct violation
|
||
of de Boor's First Rule of writing makefiles:
|
||
.QP
|
||
.I
|
||
Anything that needs to be written more than once
|
||
should be placed in a variable.
|
||
.IP "\&"
|
||
I cannot emphasize this enough as being very important to the
|
||
maintenance of a makefile and its program.
|
||
.IP 2)
|
||
There is no way to alter the way compilations are performed short of
|
||
editing the makefile and making the change in all places. This is evil
|
||
and violates de Boor's Second Rule, which follows directly from the
|
||
first:
|
||
.QP
|
||
.I
|
||
Any flags or programs used inside a makefile should be placed in a variable so
|
||
they may be changed, temporarily or permanently, with the greatest ease.
|
||
.LP
|
||
The makefile should more properly read:
|
||
.DS
|
||
OBJS = main.o parse.o output.o
|
||
expr : $(OBJS)
|
||
$(CC) $(CFLAGS) -o $(.TARGET) $(.ALLSRC)
|
||
main.o : main.c
|
||
$(CC) $(CFLAGS) -c main.c
|
||
parse.o : parse.c
|
||
$(CC) $(CFLAGS) -c parse.c
|
||
output.o : output.c
|
||
$(CC) $(CFLAGS) -c output.c
|
||
$(OBJS) : defs.h
|
||
.DE
|
||
Alternatively, if you like the idea of dynamic sources mentioned in
|
||
section 2.3.1,
|
||
.Rm 0 2.3.1
|
||
.Rd 4
|
||
.Ix 0 ref "dynamic source"
|
||
.Ix 0 ref source dynamic
|
||
you could write it like this:
|
||
.DS
|
||
OBJS = main.o parse.o output.o
|
||
expr : $(OBJS)
|
||
$(CC) $(CFLAGS) -o $(.TARGET) $(.ALLSRC)
|
||
$(OBJS) : $(.PREFIX).c defs.h
|
||
$(CC) $(CFLAGS) -c $(.PREFIX).c
|
||
.DE
|
||
These two rules and examples lead to de Boor's First Corollary:
|
||
.QP
|
||
.I
|
||
Variables are your friends.
|
||
.LP
|
||
Once you've written the makefile comes the sometimes-difficult task of
|
||
.Ix 0 ref debugging
|
||
making sure the darn thing works. Your most helpful tool to make sure
|
||
the makefile is at least syntactically correct is the
|
||
.B \-n
|
||
.Ix 0 ref flags -n
|
||
flag, which allows you to see if PMake will choke on the makefile. The
|
||
second thing the
|
||
.B \-n
|
||
flag lets you do is see what PMake would do without it actually doing
|
||
it, thus you can make sure the right commands would be executed were
|
||
you to give PMake its head.
|
||
.LP
|
||
When you find your makefile isn't behaving as you hoped, the first
|
||
question that comes to mind (after ``What time is it, anyway?'') is
|
||
``Why not?'' In answering this, two flags will serve you well:
|
||
.CW "-d m" '' ``
|
||
.Ix 0 ref flags -d
|
||
and
|
||
.CW "-p 2" .'' ``
|
||
.Ix 0 ref flags -p
|
||
The first causes PMake to tell you as it examines each target in the
|
||
makefile and indicate why it is deciding whatever it is deciding. You
|
||
can then use the information printed for other targets to see where
|
||
you went wrong. The
|
||
.CW "-p 2" '' ``
|
||
flag makes PMake print out its internal state when it is done,
|
||
allowing you to see that you forgot to make that one chapter depend on
|
||
that file of macros you just got a new version of. The output from
|
||
.CW "-p 2" '' ``
|
||
is intended to resemble closely a real makefile, but with additional
|
||
information provided and with variables expanded in those commands
|
||
PMake actually printed or executed.
|
||
.LP
|
||
Something to be especially careful about is circular dependencies.
|
||
.Ix 0 def dependency circular
|
||
E.g.
|
||
.DS
|
||
a : b
|
||
b : c d
|
||
d : a
|
||
.DE
|
||
In this case, because of how PMake works,
|
||
.CW c
|
||
is the only thing PMake will examine, because
|
||
.CW d
|
||
and
|
||
.CW a
|
||
will effectively fall off the edge of the universe, making it
|
||
impossible to examine
|
||
.CW b
|
||
(or them, for that matter).
|
||
PMake will tell you (if run in its normal mode) all the targets
|
||
involved in any cycle it looked at (i.e. if you have two cycles in the
|
||
graph (naughty, naughty), but only try to make a target in one of
|
||
them, PMake will only tell you about that one. You'll have to try to
|
||
make the other to find the second cycle). When run as Make, it will
|
||
only print the first target in the cycle.
|
||
.xH 2 Invoking PMake
|
||
.LP
|
||
.Ix 0 ref flags
|
||
.Ix 0 ref arguments
|
||
.Ix 0 ref usage
|
||
PMake comes with a wide variety of flags to choose from.
|
||
They may appear in any order, interspersed with command-line variable
|
||
assignments and targets to create.
|
||
The flags are as follows:
|
||
.IP "\fB\-d\fP \fIwhat\fP"
|
||
.Ix 0 def flags -d
|
||
.Ix 0 ref debugging
|
||
This causes PMake to spew out debugging information that
|
||
may prove useful to you. If you can't
|
||
figure out why PMake is doing what it's doing, you might try using
|
||
this flag. The
|
||
.I what
|
||
parameter is a string of single characters that tell PMake what
|
||
aspects you are interested in. Most of what I describe will make
|
||
little sense to you, unless you've dealt with Make before. Just
|
||
remember where this table is and come back to it as you read on.
|
||
The characters and the information they produce are as follows:
|
||
.RS
|
||
.IP a
|
||
Archive searching and caching.
|
||
.IP c
|
||
Conditional evaluation.
|
||
.IP d
|
||
The searching and caching of directories.
|
||
.IP j
|
||
Various snippets of information related to the running of the multiple
|
||
shells. Not particularly interesting.
|
||
.IP m
|
||
The making of each target: what target is being examined; when it was
|
||
last modified; whether it is out-of-date; etc.
|
||
.IP p
|
||
Makefile parsing.
|
||
.IP r
|
||
Remote execution.
|
||
.IP s
|
||
The application of suffix-transformation rules. (See chapter 3)
|
||
.IP t
|
||
The maintenance of the list of targets.
|
||
.IP v
|
||
Variable assignment.
|
||
.RE
|
||
.IP "\&"
|
||
Of these all, the
|
||
.CW m
|
||
and
|
||
.CW s
|
||
letters will be most useful to you.
|
||
If the
|
||
.B \-d
|
||
is the final argument or the argument from which it would get these
|
||
key letters (see below for a note about which argument would be used)
|
||
begins with a
|
||
.B \- ,
|
||
all of these debugging flags will be set, resulting in massive amounts
|
||
of output.
|
||
.IP "\fB\-f\fP \fImakefile\fP"
|
||
.Ix 0 def flags -f
|
||
Specify a makefile to read different from the standard makefiles
|
||
.CW Makefile "\&" (
|
||
or
|
||
.CW makefile ).
|
||
.Ix 0 ref makefile default
|
||
.Ix 0 ref makefile other
|
||
If
|
||
.I makefile
|
||
is ``\-'', PMake uses the standard input. This is useful for making
|
||
quick and dirty makefiles.\|.\|.
|
||
.Ix 0 ref makefile "quick and dirty"
|
||
.IP \fB\-h\fP
|
||
.Ix 0 def flags -h
|
||
Prints out a summary of the various flags PMake accepts. It can also
|
||
be used to find out what level of concurrency was compiled into the
|
||
version of PMake you are using (look at
|
||
.B \-J
|
||
and
|
||
.B \-L )
|
||
and various other information on how PMake was configured.
|
||
.Ix 0 ref configuration
|
||
.Ix 0 ref makefile system
|
||
.IP \fB\-i\fP
|
||
.Ix 0 def flags -i
|
||
If you give this flag, PMake will ignore non-zero status returned
|
||
by any of its shells. It's like placing a `\-' before all the commands
|
||
in the makefile.
|
||
.IP \fB\-k\fP
|
||
.Ix 0 def flags -k
|
||
This is similar to
|
||
.B \-i
|
||
in that it allows PMake to continue when it sees an error, but unlike
|
||
.B \-i ,
|
||
where PMake continues blithely as if nothing went wrong,
|
||
.B \-k
|
||
causes it to recognize the error and only continue work on those
|
||
things that don't depend on the target, either directly or indirectly (through
|
||
depending on something that depends on it), whose creation returned the error.
|
||
The `k' is for ``keep going''.\|.\|.
|
||
.Ix 0 ref target
|
||
.IP \fB\-l\fP
|
||
.Ix 0 def flags -l
|
||
PMake has the ability to lock a directory against other
|
||
people executing it in the same directory (by means of a file called
|
||
``LOCK.make'' that it creates and checks for in the directory). This
|
||
is a Good Thing because two people doing the same thing in the same place
|
||
can be disastrous for the final product (too many cooks and all that).
|
||
Whether this locking is the default is up to your system
|
||
administrator. If locking is on,
|
||
.B \-l
|
||
will turn it off, and vice versa. Note that this locking will not
|
||
prevent \fIyou\fP from invoking PMake twice in the same place \*- if
|
||
you own the lock file, PMake will warn you about it but continue to execute.
|
||
.IP "\fB\-m\fP \fIdirectory\fP"
|
||
.Ix 0 def flags -m
|
||
Tells PMake another place to search for included makefiles via the <...>
|
||
style. Several
|
||
.B \-m
|
||
options can be given to form a search path. If this construct is used the
|
||
default system makefile search path is completely overridden.
|
||
To be explained in chapter 3, section 3.2.
|
||
.Rm 2 3.2
|
||
.IP \fB\-n\fP
|
||
.Ix 0 def flags -n
|
||
This flag tells PMake not to execute the commands needed to update the
|
||
out-of-date targets in the makefile. Rather, PMake will simply print
|
||
the commands it would have executed and exit. This is particularly
|
||
useful for checking the correctness of a makefile. If PMake doesn't do
|
||
what you expect it to, it's a good chance the makefile is wrong.
|
||
.IP "\fB\-p\fP \fInumber\fP"
|
||
.Ix 0 def flags -p
|
||
.Ix 0 ref debugging
|
||
This causes PMake to print its input in a reasonable form, though
|
||
not necessarily one that would make immediate sense to anyone but me. The
|
||
.I number
|
||
is a bitwise-or of 1 and 2 where 1 means it should print the input
|
||
before doing any processing and 2 says it should print it after
|
||
everything has been re-created. Thus
|
||
.CW "\-p 3"
|
||
would print it twice\*-once before processing and once after (you
|
||
might find the difference between the two interesting). This is mostly
|
||
useful to me, but you may find it informative in some bizarre circumstances.
|
||
.IP \fB\-q\fP
|
||
.Ix 0 def flags -q
|
||
If you give PMake this flag, it will not try to re-create anything. It
|
||
will just see if anything is out-of-date and exit non-zero if so.
|
||
.IP \fB\-r\fP
|
||
.Ix 0 def flags -r
|
||
When PMake starts up, it reads a default makefile that tells it what
|
||
sort of system it's on and gives it some idea of what to do if you
|
||
don't tell it anything. I'll tell you about it in chapter 3. If you
|
||
give this flag, PMake won't read the default makefile.
|
||
.IP \fB\-s\fP
|
||
.Ix 0 def flags -s
|
||
This causes PMake to not print commands before they're executed. It
|
||
is the equivalent of putting an `@' before every command in the
|
||
makefile.
|
||
.IP \fB\-t\fP
|
||
.Ix 0 def flags -t
|
||
Rather than try to re-create a target, PMake will simply ``touch'' it
|
||
so as to make it appear up-to-date. If the target didn't exist before,
|
||
it will when PMake finishes, but if the target did exist, it will
|
||
appear to have been updated.
|
||
.IP \fB\-v\fP
|
||
.Ix 0 def flags -v
|
||
This is a mixed-compatibility flag intended to mimic the System V
|
||
version of Make. It is the same as giving
|
||
.B \-B ,
|
||
and
|
||
.B \-V
|
||
as well as turning off directory locking. Targets can still be created
|
||
in parallel, however. This is the mode PMake will enter if it is
|
||
invoked either as
|
||
.CW smake '' ``
|
||
or
|
||
.CW vmake ''. ``
|
||
.IP \fB\-x\fP
|
||
.Ix 0 def flags -x
|
||
This tells PMake it's ok to export jobs to other machines, if they're
|
||
available. It is used when running in Make mode, as exporting in this
|
||
mode tends to make things run slower than if the commands were just
|
||
executed locally.
|
||
.IP \fB\-B\fP
|
||
.Ix 0 ref compatibility
|
||
.Ix 0 def flags -B
|
||
Forces PMake to be as backwards-compatible with Make as possible while
|
||
still being itself.
|
||
This includes:
|
||
.RS
|
||
.IP \(bu 2
|
||
Executing one shell per shell command
|
||
.IP \(bu 2
|
||
Expanding anything that looks even vaguely like a variable, with the
|
||
empty string replacing any variable PMake doesn't know.
|
||
.IP \(bu 2
|
||
Refusing to allow you to escape a `#' with a backslash.
|
||
.IP \(bu 2
|
||
Permitting undefined variables on dependency lines and conditionals
|
||
(see below). Normally this causes PMake to abort.
|
||
.RE
|
||
.IP \fB\-C\fP
|
||
.Ix 0 def flags -C
|
||
This nullifies any and all compatibility mode flags you may have given
|
||
or implied up to the time the
|
||
.B \-C
|
||
is encountered. It is useful mostly in a makefile that you wrote for PMake
|
||
to avoid bad things happening when someone runs PMake as
|
||
.CW make '' ``
|
||
or has things set in the environment that tell it to be compatible.
|
||
.B \-C
|
||
is
|
||
.I not
|
||
placed in the
|
||
.CW PMAKE
|
||
environment variable or the
|
||
.CW .MAKEFLAGS
|
||
or
|
||
.CW MFLAGS
|
||
global variables.
|
||
.Ix 0 ref variable environment PMAKE
|
||
.Ix 0 ref variable global .MAKEFLAGS
|
||
.Ix 0 ref variable global MFLAGS
|
||
.Ix 0 ref .MAKEFLAGS variable
|
||
.Ix 0 ref MFLAGS
|
||
.IP "\fB\-D\fP \fIvariable\fP"
|
||
.Ix 0 def flags -D
|
||
Allows you to define a variable to have
|
||
.CW 1 '' ``
|
||
as its value. The variable is a global variable, not a command-line
|
||
variable. This is useful mostly for people who are used to the C
|
||
compiler arguments and those using conditionals, which I'll get into
|
||
in section 4.3
|
||
.Rm 1 4.3
|
||
.IP "\fB\-I\fP \fIdirectory\fP"
|
||
.Ix 0 def flags -I
|
||
Tells PMake another place to search for included makefiles. Yet
|
||
another thing to be explained in chapter 3 (section 3.2, to be
|
||
precise).
|
||
.Rm 2 3.2
|
||
.IP "\fB\-J\fP \fInumber\fP"
|
||
.Ix 0 def flags -J
|
||
Gives the absolute maximum number of targets to create at once on both
|
||
local and remote machines.
|
||
.IP "\fB\-L\fP \fInumber\fP"
|
||
.Ix 0 def flags -L
|
||
This specifies the maximum number of targets to create on the local
|
||
machine at once. This may be 0, though you should be wary of doing
|
||
this, as PMake may hang until a remote machine becomes available, if
|
||
one is not available when it is started.
|
||
.IP \fB\-M\fP
|
||
.Ix 0 ref compatibility
|
||
.Ix 0 def flags -M
|
||
This is the flag that provides absolute, complete, full compatibility
|
||
with Make. It still allows you to use all but a few of the features of
|
||
PMake, but it is non-parallel. This is the mode PMake enters if you
|
||
call it
|
||
.CW make .'' ``
|
||
.IP \fB\-P\fP
|
||
.Ix 0 def flags -P
|
||
.Ix 0 ref "output control"
|
||
When creating targets in parallel, several shells are executing at
|
||
once, each wanting to write its own two cent's-worth to the screen.
|
||
This output must be captured by PMake in some way in order to prevent
|
||
the screen from being filled with garbage even more indecipherable
|
||
than you usually see. PMake has two ways of doing this, one of which
|
||
provides for much cleaner output and a clear separation between the
|
||
output of different jobs, the other of which provides a more immediate
|
||
response so one can tell what is really happening. The former is done
|
||
by notifying you when the creation of a target starts, capturing the
|
||
output and transferring it to the screen all at once when the job
|
||
finishes. The latter is done by catching the output of the shell (and
|
||
its children) and buffering it until an entire line is received, then
|
||
printing that line preceded by an indication of which job produced
|
||
the output. Since I prefer this second method, it is the one used by
|
||
default. The first method will be used if you give the
|
||
.B \-P
|
||
flag to PMake.
|
||
.IP \fB\-V\fP
|
||
.Ix 0 def flags -V
|
||
As mentioned before, the
|
||
.B \-V
|
||
flag tells PMake to use Make's style of expanding variables,
|
||
substituting the empty string for any variable it doesn't know.
|
||
.IP \fB\-W\fP
|
||
.Ix 0 def flags -W
|
||
There are several times when PMake will print a message at you that is
|
||
only a warning, i.e. it can continue to work in spite of your having
|
||
done something silly (such as forgotten a leading tab for a shell
|
||
command). Sometimes you are well aware of silly things you have done
|
||
and would like PMake to stop bothering you. This flag tells it to shut
|
||
up about anything non-fatal.
|
||
.IP \fB\-X\fP
|
||
.Ix 0 def flags -X
|
||
This flag causes PMake to not attempt to export any jobs to another
|
||
machine.
|
||
.LP
|
||
Several flags may follow a single `\-'. Those flags that require
|
||
arguments take them from successive parameters. E.g.
|
||
.DS
|
||
pmake -fDnI server.mk DEBUG /chip2/X/server/include
|
||
.DE
|
||
will cause PMake to read
|
||
.CW server.mk
|
||
as the input makefile, define the variable
|
||
.CW DEBUG
|
||
as a global variable and look for included makefiles in the directory
|
||
.CW /chip2/X/server/include .
|
||
.xH 2 Summary
|
||
.LP
|
||
A makefile is made of four types of lines:
|
||
.RS
|
||
.IP \(bu 2
|
||
Dependency lines
|
||
.IP \(bu 2
|
||
Creation commands
|
||
.IP \(bu 2
|
||
Variable assignments
|
||
.IP \(bu 2
|
||
Comments, include statements and conditional directives
|
||
.RE
|
||
.LP
|
||
A dependency line is a list of one or more targets, an operator
|
||
.CW : ', (`
|
||
.CW :: ', `
|
||
or
|
||
.CW ! '), `
|
||
and a list of zero or more sources. Sources may contain wildcards and
|
||
certain local variables.
|
||
.LP
|
||
A creation command is a regular shell command preceded by a tab. In
|
||
addition, if the first two characters after the tab (and other
|
||
whitespace) are a combination of
|
||
.CW @ ' `
|
||
or
|
||
.CW - ', `
|
||
PMake will cause the command to not be printed (if the character is
|
||
.CW @ ') `
|
||
or errors from it to be ignored (if
|
||
.CW - '). `
|
||
A blank line, dependency line or variable assignment terminates a
|
||
creation script. There may be only one creation script for each target
|
||
with a
|
||
.CW : ' `
|
||
or
|
||
.CW ! ' `
|
||
operator.
|
||
.LP
|
||
Variables are places to store text. They may be unconditionally
|
||
assigned-to using the
|
||
.CW = ' `
|
||
.Ix 0 ref =
|
||
.Ix 0 ref variable assignment
|
||
operator, appended-to using the
|
||
.CW += ' `
|
||
.Ix 0 ref +=
|
||
.Ix 0 ref variable assignment appended
|
||
operator, conditionally (if the variable is undefined) assigned-to
|
||
with the
|
||
.CW ?= ' `
|
||
.Ix 0 ref ?=
|
||
.Ix 0 ref variable assignment conditional
|
||
operator, and assigned-to with variable expansion with the
|
||
.CW := ' `
|
||
.Ix 0 ref :=
|
||
.Ix 0 ref variable assignment expanded
|
||
operator. The output of a shell command may be assigned to a variable
|
||
using the
|
||
.CW != ' `
|
||
.Ix 0 ref !=
|
||
.Ix 0 ref variable assignment shell-output
|
||
operator. Variables may be expanded (their value inserted) by enclosing
|
||
their name in parentheses or curly braces, preceded by a dollar sign.
|
||
A dollar sign may be escaped with another dollar sign. Variables are
|
||
not expanded if PMake doesn't know about them. There are seven local
|
||
variables:
|
||
.CW .TARGET ,
|
||
.CW .ALLSRC ,
|
||
.CW .OODATE ,
|
||
.CW .PREFIX ,
|
||
.CW .IMPSRC ,
|
||
.CW .ARCHIVE ,
|
||
and
|
||
.CW .MEMBER .
|
||
Four of them
|
||
.CW .TARGET , (
|
||
.CW .PREFIX ,
|
||
.CW .ARCHIVE ,
|
||
and
|
||
.CW .MEMBER )
|
||
may be used to specify ``dynamic sources.''
|
||
.Ix 0 ref "dynamic source"
|
||
.Ix 0 ref source dynamic
|
||
Variables are good. Know them. Love them. Live them.
|
||
.LP
|
||
Debugging of makefiles is best accomplished using the
|
||
.B \-n ,
|
||
.B "\-d m" ,
|
||
and
|
||
.B "\-p 2"
|
||
flags.
|
||
.xH 2 Exercises
|
||
.ce
|
||
\s+4\fBTBA\fP\s0
|
||
.xH 1 Short-cuts and Other Nice Things
|
||
.LP
|
||
Based on what I've told you so far, you may have gotten the impression
|
||
that PMake is just a way of storing away commands and making sure you
|
||
don't forget to compile something. Good. That's just what it is.
|
||
However, the ways I've described have been inelegant, at best, and
|
||
painful, at worst.
|
||
This chapter contains things that make the
|
||
writing of makefiles easier and the makefiles themselves shorter and
|
||
easier to modify (and, occasionally, simpler). In this chapter, I
|
||
assume you are somewhat more
|
||
familiar with Sprite (or UNIX, if that's what you're using) than I did
|
||
in chapter 2, just so you're on your toes.
|
||
So without further ado...
|
||
.xH 2 Transformation Rules
|
||
.LP
|
||
As you know, a file's name consists of two parts: a base name, which
|
||
gives some hint as to the contents of the file, and a suffix, which
|
||
usually indicates the format of the file.
|
||
Over the years, as
|
||
.UX
|
||
has developed,
|
||
naming conventions, with regard to suffixes, have also developed that have
|
||
become almost as incontrovertible as Law. E.g. a file ending in
|
||
.CW .c
|
||
is assumed to contain C source code; one with a
|
||
.CW .o
|
||
suffix is assumed to be a compiled, relocatable object file that may
|
||
be linked into any program; a file with a
|
||
.CW .ms
|
||
suffix is usually a text file to be processed by Troff with the \-ms
|
||
macro package, and so on.
|
||
One of the best aspects of both Make and PMake comes from their
|
||
understanding of how the suffix of a file pertains to its contents and
|
||
their ability to do things with a file based solely on its suffix. This
|
||
ability comes from something known as a transformation rule. A
|
||
transformation rule specifies how to change a file with one suffix
|
||
into a file with another suffix.
|
||
.LP
|
||
A transformation rule looks much like a dependency line, except the
|
||
target is made of two known suffixes stuck together. Suffixes are made
|
||
known to PMake by placing them as sources on a dependency line whose
|
||
target is the special target
|
||
.CW .SUFFIXES .
|
||
E.g.
|
||
.DS
|
||
\&.SUFFIXES : .o .c
|
||
\&.c.o :
|
||
$(CC) $(CFLAGS) -c $(.IMPSRC)
|
||
.DE
|
||
The creation script attached to the target is used to transform a file with
|
||
the first suffix (in this case,
|
||
.CW .c )
|
||
into a file with the second suffix (here,
|
||
.CW .o ).
|
||
In addition, the target inherits whatever attributes have been applied
|
||
to the transformation rule.
|
||
The simple rule given above says that to transform a C source file
|
||
into an object file, you compile it using
|
||
.CW cc
|
||
with the
|
||
.CW \-c
|
||
flag.
|
||
This rule is taken straight from the system makefile. Many
|
||
transformation rules (and suffixes) are defined there, and I refer you
|
||
to it for more examples (type
|
||
.CW "pmake -h" '' ``
|
||
to find out where it is).
|
||
.LP
|
||
There are several things to note about the transformation rule given
|
||
above:
|
||
.RS
|
||
.IP 1)
|
||
The
|
||
.CW .IMPSRC
|
||
variable.
|
||
.Ix 0 def variable local .IMPSRC
|
||
.Ix 0 def .IMPSRC
|
||
This variable is set to the ``implied source'' (the file from which
|
||
the target is being created; the one with the first suffix), which, in this
|
||
case, is the .c file.
|
||
.IP 2)
|
||
The
|
||
.CW CFLAGS
|
||
variable. Almost all of the transformation rules in the system
|
||
makefile are set up using variables that you can alter in your
|
||
makefile to tailor the rule to your needs. In this case, if you want
|
||
all your C files to be compiled with the
|
||
.B \-g
|
||
flag, to provide information for
|
||
.CW dbx ,
|
||
you would set the
|
||
.CW CFLAGS
|
||
variable to contain
|
||
.CW -g
|
||
.CW "CFLAGS = -g" '') (``
|
||
and PMake would take care of the rest.
|
||
.RE
|
||
.LP
|
||
To give you a quick example, the makefile in 2.3.4
|
||
.Rm 3 2.3.4
|
||
could be changed to this:
|
||
.DS
|
||
OBJS = a.o b.o c.o
|
||
program : $(OBJS)
|
||
$(CC) -o $(.TARGET) $(.ALLSRC)
|
||
$(OBJS) : defs.h
|
||
.DE
|
||
The transformation rule I gave above takes the place of the 6 lines\**
|
||
.FS
|
||
This is also somewhat cleaner, I think, than the dynamic source
|
||
solution presented in 2.6
|
||
.FE
|
||
.Rm 4 2.6
|
||
.DS
|
||
a.o : a.c
|
||
cc -c a.c
|
||
b.o : b.c
|
||
cc -c b.c
|
||
c.o : c.c
|
||
cc -c c.c
|
||
.DE
|
||
.LP
|
||
Now you may be wondering about the dependency between the
|
||
.CW .o
|
||
and
|
||
.CW .c
|
||
files \*- it's not mentioned anywhere in the new makefile. This is
|
||
because it isn't needed: one of the effects of applying a
|
||
transformation rule is the target comes to depend on the implied
|
||
source. That's why it's called the implied
|
||
.I source .
|
||
.LP
|
||
For a more detailed example. Say you have a makefile like this:
|
||
.DS
|
||
a.out : a.o b.o
|
||
$(CC) $(.ALLSRC)
|
||
.DE
|
||
and a directory set up like this:
|
||
.DS
|
||
total 4
|
||
-rw-rw-r-- 1 deboor 34 Sep 7 00:43 Makefile
|
||
-rw-rw-r-- 1 deboor 119 Oct 3 19:39 a.c
|
||
-rw-rw-r-- 1 deboor 201 Sep 7 00:43 a.o
|
||
-rw-rw-r-- 1 deboor 69 Sep 7 00:43 b.c
|
||
.DE
|
||
While just typing
|
||
.CW pmake '' ``
|
||
will do the right thing, it's much more informative to type
|
||
.CW "pmake -d s" ''. ``
|
||
This will show you what PMake is up to as it processes the files. In
|
||
this case, PMake prints the following:
|
||
.DS
|
||
Suff_FindDeps (a.out)
|
||
using existing source a.o
|
||
applying .o -> .out to "a.o"
|
||
Suff_FindDeps (a.o)
|
||
trying a.c...got it
|
||
applying .c -> .o to "a.c"
|
||
Suff_FindDeps (b.o)
|
||
trying b.c...got it
|
||
applying .c -> .o to "b.c"
|
||
Suff_FindDeps (a.c)
|
||
trying a.y...not there
|
||
trying a.l...not there
|
||
trying a.c,v...not there
|
||
trying a.y,v...not there
|
||
trying a.l,v...not there
|
||
Suff_FindDeps (b.c)
|
||
trying b.y...not there
|
||
trying b.l...not there
|
||
trying b.c,v...not there
|
||
trying b.y,v...not there
|
||
trying b.l,v...not there
|
||
--- a.o ---
|
||
cc -c a.c
|
||
--- b.o ---
|
||
cc -c b.c
|
||
--- a.out ---
|
||
cc a.o b.o
|
||
.DE
|
||
.LP
|
||
.CW Suff_FindDeps
|
||
is the name of a function in PMake that is called to check for implied
|
||
sources for a target using transformation rules.
|
||
The transformations it tries are, naturally
|
||
enough, limited to the ones that have been defined (a transformation
|
||
may be defined multiple times, by the way, but only the most recent
|
||
one will be used). You will notice, however, that there is a definite
|
||
order to the suffixes that are tried. This order is set by the
|
||
relative positions of the suffixes on the
|
||
.CW .SUFFIXES
|
||
line \*- the earlier a suffix appears, the earlier it is checked as
|
||
the source of a transformation. Once a suffix has been defined, the
|
||
only way to change its position in the pecking order is to remove all
|
||
the suffixes (by having a
|
||
.CW .SUFFIXES
|
||
dependency line with no sources) and redefine them in the order you
|
||
want. (Previously-defined transformation rules will be automatically
|
||
redefined as the suffixes they involve are re-entered.)
|
||
.LP
|
||
Another way to affect the search order is to make the dependency
|
||
explicit. In the above example,
|
||
.CW a.out
|
||
depends on
|
||
.CW a.o
|
||
and
|
||
.CW b.o .
|
||
Since a transformation exists from
|
||
.CW .o
|
||
to
|
||
.CW .out ,
|
||
PMake uses that, as indicated by the
|
||
.CW "using existing source a.o" '' ``
|
||
message.
|
||
.LP
|
||
The search for a transformation starts from the suffix of the target
|
||
and continues through all the defined transformations, in the order
|
||
dictated by the suffix ranking, until an existing file with the same
|
||
base (the target name minus the suffix and any leading directories) is
|
||
found. At that point, one or more transformation rules will have been
|
||
found to change the one existing file into the target.
|
||
.LP
|
||
For example, ignoring what's in the system makefile for now, say you
|
||
have a makefile like this:
|
||
.DS
|
||
\&.SUFFIXES : .out .o .c .y .l
|
||
\&.l.c :
|
||
lex $(.IMPSRC)
|
||
mv lex.yy.c $(.TARGET)
|
||
\&.y.c :
|
||
yacc $(.IMPSRC)
|
||
mv y.tab.c $(.TARGET)
|
||
\&.c.o :
|
||
cc -c $(.IMPSRC)
|
||
\&.o.out :
|
||
cc -o $(.TARGET) $(.IMPSRC)
|
||
.DE
|
||
and the single file
|
||
.CW jive.l .
|
||
If you were to type
|
||
.CW "pmake -rd ms jive.out" ,'' ``
|
||
you would get the following output for
|
||
.CW jive.out :
|
||
.DS
|
||
Suff_FindDeps (jive.out)
|
||
trying jive.o...not there
|
||
trying jive.c...not there
|
||
trying jive.y...not there
|
||
trying jive.l...got it
|
||
applying .l -> .c to "jive.l"
|
||
applying .c -> .o to "jive.c"
|
||
applying .o -> .out to "jive.o"
|
||
.DE
|
||
and this is why: PMake starts with the target
|
||
.CW jive.out ,
|
||
figures out its suffix
|
||
.CW .out ) (
|
||
and looks for things it can transform to a
|
||
.CW .out
|
||
file. In this case, it only finds
|
||
.CW .o ,
|
||
so it looks for the file
|
||
.CW jive.o .
|
||
It fails to find it, so it looks for transformations into a
|
||
.CW .o
|
||
file. Again it has only one choice:
|
||
.CW .c .
|
||
So it looks for
|
||
.CW jive.c
|
||
and, as you know, fails to find it. At this point it has two choices:
|
||
it can create the
|
||
.CW .c
|
||
file from either a
|
||
.CW .y
|
||
file or a
|
||
.CW .l
|
||
file. Since
|
||
.CW .y
|
||
came first on the
|
||
.CW .SUFFIXES
|
||
line, it checks for
|
||
.CW jive.y
|
||
first, but can't find it, so it looks for
|
||
.CW jive.l
|
||
and, lo and behold, there it is.
|
||
At this point, it has defined a transformation path as follows:
|
||
.CW .l
|
||
\(->
|
||
.CW .c
|
||
\(->
|
||
.CW .o
|
||
\(->
|
||
.CW .out
|
||
and applies the transformation rules accordingly. For completeness,
|
||
and to give you a better idea of what PMake actually did with this
|
||
three-step transformation, this is what PMake printed for the rest of
|
||
the process:
|
||
.DS
|
||
Suff_FindDeps (jive.o)
|
||
using existing source jive.c
|
||
applying .c -> .o to "jive.c"
|
||
Suff_FindDeps (jive.c)
|
||
using existing source jive.l
|
||
applying .l -> .c to "jive.l"
|
||
Suff_FindDeps (jive.l)
|
||
Examining jive.l...modified 17:16:01 Oct 4, 1987...up-to-date
|
||
Examining jive.c...non-existent...out-of-date
|
||
--- jive.c ---
|
||
lex jive.l
|
||
\&.\|.\|. meaningless lex output deleted .\|.\|.
|
||
mv lex.yy.c jive.c
|
||
Examining jive.o...non-existent...out-of-date
|
||
--- jive.o ---
|
||
cc -c jive.c
|
||
Examining jive.out...non-existent...out-of-date
|
||
--- jive.out ---
|
||
cc -o jive.out jive.o
|
||
.DE
|
||
.LP
|
||
One final question remains: what does PMake do with targets that have
|
||
no known suffix? PMake simply pretends it actually has a known suffix
|
||
and searches for transformations accordingly.
|
||
The suffix it chooses is the source for the
|
||
.CW .NULL
|
||
.Ix 0 ref .NULL
|
||
target mentioned later. In the system makefile,
|
||
.CW .out
|
||
is chosen as the ``null suffix''
|
||
.Ix 0 def suffix null
|
||
.Ix 0 def "null suffix"
|
||
because most people use PMake to create programs. You are, however,
|
||
free and welcome to change it to a suffix of your own choosing.
|
||
The null suffix is ignored, however, when PMake is in compatibility
|
||
mode (see chapter 4).
|
||
.xH 2 Including Other Makefiles
|
||
.Ix 0 def makefile inclusion
|
||
.Rd 2
|
||
.LP
|
||
Just as for programs, it is often useful to extract certain parts of a
|
||
makefile into another file and just include it in other makefiles
|
||
somehow. Many compilers allow you say something like
|
||
.DS
|
||
#include "defs.h"
|
||
.DE
|
||
to include the contents of
|
||
.CW defs.h
|
||
in the source file. PMake allows you to do the same thing for
|
||
makefiles, with the added ability to use variables in the filenames.
|
||
An include directive in a makefile looks either like this:
|
||
.DS
|
||
#include <file>
|
||
.DE
|
||
or this
|
||
.DS
|
||
#include "file"
|
||
.DE
|
||
The difference between the two is where PMake searches for the file:
|
||
the first way, PMake will look for
|
||
the file only in the system makefile directory (or directories)
|
||
(to find out what that directory is, give PMake the
|
||
.B \-h
|
||
flag).
|
||
.Ix 0 ref flags -h
|
||
The system makefile directory search path can be overridden via the
|
||
.B \-m
|
||
option.
|
||
.Ix 0 ref flags -m
|
||
For files in double-quotes, the search is more complex:
|
||
.RS
|
||
.IP 1)
|
||
The directory of the makefile that's including the file.
|
||
.IP 2)
|
||
The current directory (the one in which you invoked PMake).
|
||
.IP 3)
|
||
The directories given by you using
|
||
.B \-I
|
||
flags, in the order in which you gave them.
|
||
.IP 4)
|
||
Directories given by
|
||
.CW .PATH
|
||
dependency lines (see chapter 4).
|
||
.IP 5)
|
||
The system makefile directory.
|
||
.RE
|
||
.LP
|
||
in that order.
|
||
.LP
|
||
You are free to use PMake variables in the filename\*-PMake will
|
||
expand them before searching for the file. You must specify the
|
||
searching method with either angle brackets or double-quotes
|
||
.I outside
|
||
of a variable expansion. I.e. the following
|
||
.DS
|
||
SYSTEM = <command.mk>
|
||
|
||
#include $(SYSTEM)
|
||
.DE
|
||
won't work.
|
||
.xH 2 Saving Commands
|
||
.LP
|
||
.Ix 0 def ...
|
||
There may come a time when you will want to save certain commands to
|
||
be executed when everything else is done. For instance: you're
|
||
making several different libraries at one time and you want to create the
|
||
members in parallel. Problem is,
|
||
.CW ranlib
|
||
is another one of those programs that can't be run more than once in
|
||
the same directory at the same time (each one creates a file called
|
||
.CW __.SYMDEF
|
||
into which it stuffs information for the linker to use. Two of them
|
||
running at once will overwrite each other's file and the result will
|
||
be garbage for both parties). You might want a way to save the ranlib
|
||
commands til the end so they can be run one after the other, thus
|
||
keeping them from trashing each other's file. PMake allows you to do
|
||
this by inserting an ellipsis (``.\|.\|.'') as a command between
|
||
commands to be run at once and those to be run later.
|
||
.LP
|
||
So for the
|
||
.CW ranlib
|
||
case above, you might do this:
|
||
.Rd 5
|
||
.DS
|
||
lib1.a : $(LIB1OBJS)
|
||
rm -f $(.TARGET)
|
||
ar cr $(.TARGET) $(.ALLSRC)
|
||
...
|
||
ranlib $(.TARGET)
|
||
|
||
lib2.a : $(LIB2OBJS)
|
||
rm -f $(.TARGET)
|
||
ar cr $(.TARGET) $(.ALLSRC)
|
||
...
|
||
ranlib $(.TARGET)
|
||
.DE
|
||
.Ix 0 ref variable local .TARGET
|
||
.Ix 0 ref variable local .ALLSRC
|
||
This would save both
|
||
.DS
|
||
ranlib $(.TARGET)
|
||
.DE
|
||
commands until the end, when they would run one after the other
|
||
(using the correct value for the
|
||
.CW .TARGET
|
||
variable, of course).
|
||
.LP
|
||
Commands saved in this manner are only executed if PMake manages to
|
||
re-create everything without an error.
|
||
.xH 2 Target Attributes
|
||
.LP
|
||
PMake allows you to give attributes to targets by means of special
|
||
sources. Like everything else PMake uses, these sources begin with a
|
||
period and are made up of all upper-case letters. There are various
|
||
reasons for using them, and I will try to give examples for most of
|
||
them. Others you'll have to find uses for yourself. Think of it as ``an
|
||
exercise for the reader.'' By placing one (or more) of these as a source on a
|
||
dependency line, you are ``marking the target(s) with that
|
||
attribute.'' That's just the way I phrase it, so you know.
|
||
.LP
|
||
Any attributes given as sources for a transformation rule are applied
|
||
to the target of the transformation rule when the rule is applied.
|
||
.Ix 0 def attributes
|
||
.Ix 0 ref source
|
||
.Ix 0 ref target
|
||
.nr pw 12
|
||
.IP .DONTCARE \n(pw
|
||
.Ix 0 def attributes .DONTCARE
|
||
.Ix 0 def .DONTCARE
|
||
If a target is marked with this attribute and PMake can't figure out
|
||
how to create it, it will ignore this fact and assume the file isn't
|
||
really needed or actually exists and PMake just can't find it. This may prove
|
||
wrong, but the error will be noted later on, not when PMake tries to create
|
||
the target so marked. This attribute also prevents PMake from
|
||
attempting to touch the target if it is given the
|
||
.B \-t
|
||
flag.
|
||
.Ix 0 ref flags -t
|
||
.IP .EXEC \n(pw
|
||
.Ix 0 def attributes .EXEC
|
||
.Ix 0 def .EXEC
|
||
This attribute causes its shell script to be executed while having no
|
||
effect on targets that depend on it. This makes the target into a sort
|
||
of subroutine. An example. Say you have some LISP files that need to
|
||
be compiled and loaded into a LISP process. To do this, you echo LISP
|
||
commands into a file and execute a LISP with this file as its input
|
||
when everything's done. Say also that you have to load other files
|
||
from another system before you can compile your files and further,
|
||
that you don't want to go through the loading and dumping unless one
|
||
of
|
||
.I your
|
||
files has changed. Your makefile might look a little bit
|
||
like this (remember, this is an educational example, and don't worry
|
||
about the
|
||
.CW COMPILE
|
||
rule, all will soon become clear, grasshopper):
|
||
.DS
|
||
system : init a.fasl b.fasl c.fasl
|
||
for i in $(.ALLSRC);
|
||
do
|
||
echo -n '(load "' >> input
|
||
echo -n ${i} >> input
|
||
echo '")' >> input
|
||
done
|
||
echo '(dump "$(.TARGET)")' >> input
|
||
lisp < input
|
||
|
||
a.fasl : a.l init COMPILE
|
||
b.fasl : b.l init COMPILE
|
||
c.fasl : c.l init COMPILE
|
||
COMPILE : .USE
|
||
echo '(compile "$(.ALLSRC)")' >> input
|
||
init : .EXEC
|
||
echo '(load-system)' > input
|
||
.DE
|
||
.Ix 0 ref .USE
|
||
.Ix 0 ref attributes .USE
|
||
.Ix 0 ref variable local .ALLSRC
|
||
.IP "\&"
|
||
.CW .EXEC
|
||
sources, don't appear in the local variables of targets that depend on
|
||
them (nor are they touched if PMake is given the
|
||
.B \-t
|
||
flag).
|
||
.Ix 0 ref flags -t
|
||
Note that all the rules, not just that for
|
||
.CW system ,
|
||
include
|
||
.CW init
|
||
as a source. This is because none of the other targets can be made
|
||
until
|
||
.CW init
|
||
has been made, thus they depend on it.
|
||
.IP .EXPORT \n(pw
|
||
.Ix 0 def attributes .EXPORT
|
||
.Ix 0 def .EXPORT
|
||
This is used to mark those targets whose creation should be sent to
|
||
another machine if at all possible. This may be used by some
|
||
exportation schemes if the exportation is expensive. You should ask
|
||
your system administrator if it is necessary.
|
||
.IP .EXPORTSAME \n(pw
|
||
.Ix 0 def attributes .EXPORTSAME
|
||
.Ix 0 def .EXPORTSAME
|
||
Tells the export system that the job should be exported to a machine
|
||
of the same architecture as the current one. Certain operations (e.g.
|
||
running text through
|
||
.CW nroff )
|
||
can be performed the same on any architecture (CPU and
|
||
operating system type), while others (e.g. compiling a program with
|
||
.CW cc )
|
||
must be performed on a machine with the same architecture. Not all
|
||
export systems will support this attribute.
|
||
.IP .IGNORE \n(pw
|
||
.Ix 0 def attributes .IGNORE
|
||
.Ix 0 def .IGNORE attribute
|
||
Giving a target the
|
||
.CW .IGNORE
|
||
attribute causes PMake to ignore errors from any of the target's commands, as
|
||
if they all had `\-' before them.
|
||
.IP .INVISIBLE \n(pw
|
||
.Ix 0 def attributes .INVISIBLE
|
||
.Ix 0 def .INVISIBLE
|
||
This allows you to specify one target as a source for another without
|
||
the one affecting the other's local variables. Useful if, say, you
|
||
have a makefile that creates two programs, one of which is used to
|
||
create the other, so it must exist before the other is created. You
|
||
could say
|
||
.DS
|
||
prog1 : $(PROG1OBJS) prog2 MAKEINSTALL
|
||
prog2 : $(PROG2OBJS) .INVISIBLE MAKEINSTALL
|
||
.DE
|
||
where
|
||
.CW MAKEINSTALL
|
||
is some complex .USE rule (see below) that depends on the
|
||
.Ix 0 ref .USE
|
||
.CW .ALLSRC
|
||
variable containing the right things. Without the
|
||
.CW .INVISIBLE
|
||
attribute for
|
||
.CW prog2 ,
|
||
the
|
||
.CW MAKEINSTALL
|
||
rule couldn't be applied. This is not as useful as it should be, and
|
||
the semantics may change (or the whole thing go away) in the
|
||
not-too-distant future.
|
||
.IP .JOIN \n(pw
|
||
.Ix 0 def attributes .JOIN
|
||
.Ix 0 def .JOIN
|
||
This is another way to avoid performing some operations in parallel
|
||
while permitting everything else to be done so. Specifically it
|
||
forces the target's shell script to be executed only if one or more of the
|
||
sources was out-of-date. In addition, the target's name,
|
||
in both its
|
||
.CW .TARGET
|
||
variable and all the local variables of any target that depends on it,
|
||
is replaced by the value of its
|
||
.CW .ALLSRC
|
||
variable.
|
||
As an example, suppose you have a program that has four libraries that
|
||
compile in the same directory along with, and at the same time as, the
|
||
program. You again have the problem with
|
||
.CW ranlib
|
||
that I mentioned earlier, only this time it's more severe: you
|
||
can't just put the ranlib off to the end since the program
|
||
will need those libraries before it can be re-created. You can do
|
||
something like this:
|
||
.DS
|
||
program : $(OBJS) libraries
|
||
cc -o $(.TARGET) $(.ALLSRC)
|
||
|
||
libraries : lib1.a lib2.a lib3.a lib4.a .JOIN
|
||
ranlib $(.OODATE)
|
||
.DE
|
||
.Ix 0 ref variable local .TARGET
|
||
.Ix 0 ref variable local .ALLSRC
|
||
.Ix 0 ref variable local .OODATE
|
||
.Ix 0 ref .TARGET
|
||
.Ix 0 ref .ALLSRC
|
||
.Ix 0 ref .OODATE
|
||
In this case, PMake will re-create the
|
||
.CW $(OBJS)
|
||
as necessary, along with
|
||
.CW lib1.a ,
|
||
.CW lib2.a ,
|
||
.CW lib3.a
|
||
and
|
||
.CW lib4.a .
|
||
It will then execute
|
||
.CW ranlib
|
||
on any library that was changed and set
|
||
.CW program 's
|
||
.CW .ALLSRC
|
||
variable to contain what's in
|
||
.CW $(OBJS)
|
||
followed by
|
||
.CW "lib1.a lib2.a lib3.a lib4.a" .'' ``
|
||
In case you're wondering, it's called
|
||
.CW .JOIN
|
||
because it joins together different threads of the ``input graph'' at
|
||
the target marked with the attribute.
|
||
Another aspect of the .JOIN attribute is it keeps the target from
|
||
being created if the
|
||
.B \-t
|
||
flag was given.
|
||
.Ix 0 ref flags -t
|
||
.IP .MAKE \n(pw
|
||
.Ix 0 def attributes .MAKE
|
||
.Ix 0 def .MAKE
|
||
The
|
||
.CW .MAKE
|
||
attribute marks its target as being a recursive invocation of PMake.
|
||
This forces PMake to execute the script associated with the target (if
|
||
it's out-of-date) even if you gave the
|
||
.B \-n
|
||
or
|
||
.B \-t
|
||
flag. By doing this, you can start at the top of a system and type
|
||
.DS
|
||
pmake -n
|
||
.DE
|
||
and have it descend the directory tree (if your makefiles are set up
|
||
correctly), printing what it would have executed if you hadn't
|
||
included the
|
||
.B \-n
|
||
flag.
|
||
.IP .NOEXPORT \n(pw
|
||
.Ix 0 def attributes .NOEXPORT
|
||
.Ix 0 def .NOEXPORT attribute
|
||
If possible, PMake will attempt to export the creation of all targets to
|
||
another machine (this depends on how PMake was configured). Sometimes,
|
||
the creation is so simple, it is pointless to send it to another
|
||
machine. If you give the target the
|
||
.CW .NOEXPORT
|
||
attribute, it will be run locally, even if you've given PMake the
|
||
.B "\-L 0"
|
||
flag.
|
||
.IP .NOTMAIN \n(pw
|
||
.Ix 0 def attributes .NOTMAIN
|
||
.Ix 0 def .NOTMAIN
|
||
Normally, if you do not specify a target to make in any other way,
|
||
PMake will take the first target on the first dependency line of a
|
||
makefile as the target to create. That target is known as the ``Main
|
||
Target'' and is labeled as such if you print the dependencies out
|
||
using the
|
||
.B \-p
|
||
flag.
|
||
.Ix 0 ref flags -p
|
||
Giving a target this attribute tells PMake that the target is
|
||
definitely
|
||
.I not
|
||
the Main Target.
|
||
This allows you to place targets in an included makefile and
|
||
have PMake create something else by default.
|
||
.IP .PRECIOUS \n(pw
|
||
.Ix 0 def attributes .PRECIOUS
|
||
.Ix 0 def .PRECIOUS attribute
|
||
When PMake is interrupted (you type control-C at the keyboard), it
|
||
will attempt to clean up after itself by removing any half-made
|
||
targets. If a target has the
|
||
.CW .PRECIOUS
|
||
attribute, however, PMake will leave it alone. An additional side
|
||
effect of the `::' operator is to mark the targets as
|
||
.CW .PRECIOUS .
|
||
.Ix 0 ref operator double-colon
|
||
.Ix 0 ref ::
|
||
.IP .SILENT \n(pw
|
||
.Ix 0 def attributes .SILENT
|
||
.Ix 0 def .SILENT attribute
|
||
Marking a target with this attribute keeps its commands from being
|
||
printed when they're executed, just as if they had an `@' in front of them.
|
||
.IP .USE \n(pw
|
||
.Ix 0 def attributes .USE
|
||
.Ix 0 def .USE
|
||
By giving a target this attribute, you turn it into PMake's equivalent
|
||
of a macro. When the target is used as a source for another target,
|
||
the other target acquires the commands, sources and attributes (except
|
||
.CW .USE )
|
||
of the source.
|
||
If the target already has commands, the
|
||
.CW .USE
|
||
target's commands are added to the end. If more than one .USE-marked
|
||
source is given to a target, the rules are applied sequentially.
|
||
.IP "\&" \n(pw
|
||
The typical .USE rule (as I call them) will use the sources of the
|
||
target to which it is applied (as stored in the
|
||
.CW .ALLSRC
|
||
variable for the target) as its ``arguments,'' if you will.
|
||
For example, you probably noticed that the commands for creating
|
||
.CW lib1.a
|
||
and
|
||
.CW lib2.a
|
||
in the example in section 3.3
|
||
.Rm 5 3.3
|
||
were exactly the same. You can use the
|
||
.CW .USE
|
||
attribute to eliminate the repetition, like so:
|
||
.DS
|
||
lib1.a : $(LIB1OBJS) MAKELIB
|
||
lib2.a : $(LIB2OBJS) MAKELIB
|
||
|
||
MAKELIB : .USE
|
||
rm -f $(.TARGET)
|
||
ar cr $(.TARGET) $(.ALLSRC)
|
||
...
|
||
ranlib $(.TARGET)
|
||
.DE
|
||
.Ix 0 ref variable local .TARGET
|
||
.Ix 0 ref variable local .ALLSRC
|
||
.IP "\&" \n(pw
|
||
Several system makefiles (not to be confused with The System Makefile)
|
||
make use of these .USE rules to make your
|
||
life easier (they're in the default, system makefile directory...take a look).
|
||
Note that the .USE rule source itself
|
||
.CW MAKELIB ) (
|
||
does not appear in any of the targets's local variables.
|
||
There is no limit to the number of times I could use the
|
||
.CW MAKELIB
|
||
rule. If there were more libraries, I could continue with
|
||
.CW "lib3.a : $(LIB3OBJS) MAKELIB" '' ``
|
||
and so on and so forth.
|
||
.xH 2 Special Targets
|
||
.LP
|
||
As there were in Make, so there are certain targets that have special
|
||
meaning to PMake. When you use one on a dependency line, it is the
|
||
only target that may appear on the left-hand-side of the operator.
|
||
.Ix 0 ref target
|
||
.Ix 0 ref operator
|
||
As for the attributes and variables, all the special targets
|
||
begin with a period and consist of upper-case letters only.
|
||
I won't describe them all in detail because some of them are rather
|
||
complex and I'll describe them in more detail than you'll want in
|
||
chapter 4.
|
||
The targets are as follows:
|
||
.nr pw 10
|
||
.IP .BEGIN \n(pw
|
||
.Ix 0 def .BEGIN
|
||
Any commands attached to this target are executed before anything else
|
||
is done. You can use it for any initialization that needs doing.
|
||
.IP .DEFAULT \n(pw
|
||
.Ix 0 def .DEFAULT
|
||
This is sort of a .USE rule for any target (that was used only as a
|
||
source) that PMake can't figure out any other way to create. It's only
|
||
``sort of'' a .USE rule because only the shell script attached to the
|
||
.CW .DEFAULT
|
||
target is used. The
|
||
.CW .IMPSRC
|
||
variable of a target that inherits
|
||
.CW .DEFAULT 's
|
||
commands is set to the target's own name.
|
||
.Ix 0 ref .IMPSRC
|
||
.Ix 0 ref variable local .IMPSRC
|
||
.IP .END \n(pw
|
||
.Ix 0 def .END
|
||
This serves a function similar to
|
||
.CW .BEGIN ,
|
||
in that commands attached to it are executed once everything has been
|
||
re-created (so long as no errors occurred). It also serves the extra
|
||
function of being a place on which PMake can hang commands you put off
|
||
to the end. Thus the script for this target will be executed before
|
||
any of the commands you save with the ``.\|.\|.''.
|
||
.Ix 0 ref ...
|
||
.IP .EXPORT \n(pw
|
||
The sources for this target are passed to the exportation system compiled
|
||
into PMake. Some systems will use these sources to configure
|
||
themselves. You should ask your system administrator about this.
|
||
.IP .IGNORE \n(pw
|
||
.Ix 0 def .IGNORE target
|
||
.Ix 0 ref .IGNORE attribute
|
||
.Ix 0 ref attributes .IGNORE
|
||
This target marks each of its sources with the
|
||
.CW .IGNORE
|
||
attribute. If you don't give it any sources, then it is like
|
||
giving the
|
||
.B \-i
|
||
flag when you invoke PMake \*- errors are ignored for all commands.
|
||
.Ix 0 ref flags -i
|
||
.IP .INCLUDES \n(pw
|
||
.Ix 0 def .INCLUDES target
|
||
.Ix 0 def variable global .INCLUDES
|
||
.Ix 0 def .INCLUDES variable
|
||
The sources for this target are taken to be suffixes that indicate a
|
||
file that can be included in a program source file.
|
||
The suffix must have already been declared with
|
||
.CW .SUFFIXES
|
||
(see below).
|
||
Any suffix so marked will have the directories on its search path
|
||
(see
|
||
.CW .PATH ,
|
||
below) placed in the
|
||
.CW .INCLUDES
|
||
variable, each preceded by a
|
||
.B \-I
|
||
flag. This variable can then be used as an argument for the compiler
|
||
in the normal fashion. The
|
||
.CW .h
|
||
suffix is already marked in this way in the system makefile.
|
||
.Ix 0 ref makefile system
|
||
E.g. if you have
|
||
.DS
|
||
\&.SUFFIXES : .bitmap
|
||
\&.PATH.bitmap : /usr/local/X/lib/bitmaps
|
||
\&.INCLUDES : .bitmap
|
||
.DE
|
||
PMake will place
|
||
.CW "-I/usr/local/X/lib/bitmaps" '' ``
|
||
in the
|
||
.CW .INCLUDES
|
||
variable and you can then say
|
||
.DS
|
||
cc $(.INCLUDES) -c xprogram.c
|
||
.DE
|
||
(Note: the
|
||
.CW .INCLUDES
|
||
variable is not actually filled in until the entire makefile has been read.)
|
||
.IP .INTERRUPT \n(pw
|
||
.Ix 0 def .INTERRUPT
|
||
When PMake is interrupted,
|
||
it will execute the commands in the script for this target, if it
|
||
exists.
|
||
.IP .LIBS \n(pw
|
||
.Ix 0 def .LIBS target
|
||
.Ix 0 def .LIBS variable
|
||
.Ix 0 def variable global .LIBS
|
||
This does for libraries what
|
||
.CW .INCLUDES
|
||
does for include files, except the flag used is
|
||
.B \-L ,
|
||
as required by those linkers that allow you to tell them where to find
|
||
libraries. The variable used is
|
||
.CW .LIBS .
|
||
Be forewarned that PMake may not have been compiled to do this if the
|
||
linker on your system doesn't accept the
|
||
.B \-L
|
||
flag, though the
|
||
.CW .LIBS
|
||
variable will always be defined once the makefile has been read.
|
||
.IP .MAIN \n(pw
|
||
.Ix 0 def .MAIN
|
||
If you didn't give a target (or targets) to create when you invoked
|
||
PMake, it will take the sources of this target as the targets to
|
||
create.
|
||
.IP .MAKEFLAGS \n(pw
|
||
.Ix 0 def .MAKEFLAGS target
|
||
This target provides a way for you to always specify flags for PMake
|
||
when the makefile is used. The flags are just as they would be typed
|
||
to the shell (except you can't use shell variables unless they're in
|
||
the environment),
|
||
though the
|
||
.B \-f
|
||
and
|
||
.B \-r
|
||
flags have no effect.
|
||
.IP .NULL \n(pw
|
||
.Ix 0 def .NULL
|
||
.Ix 0 ref suffix null
|
||
.Ix 0 ref "null suffix"
|
||
This allows you to specify what suffix PMake should pretend a file has
|
||
if, in fact, it has no known suffix. Only one suffix may be so
|
||
designated. The last source on the dependency line is the suffix that
|
||
is used (you should, however, only give one suffix.\|.\|.).
|
||
.IP .PATH \n(pw
|
||
.Ix 0 def .PATH
|
||
If you give sources for this target, PMake will take them as
|
||
directories in which to search for files it cannot find in the current
|
||
directory. If you give no sources, it will clear out any directories
|
||
added to the search path before. Since the effects of this all get
|
||
very complex, I'll leave it til chapter four to give you a complete
|
||
explanation.
|
||
.IP .PATH\fIsuffix\fP \n(pw
|
||
.Ix 0 ref .PATH
|
||
This does a similar thing to
|
||
.CW .PATH ,
|
||
but it does it only for files with the given suffix. The suffix must
|
||
have been defined already. Look at
|
||
.B "Search Paths"
|
||
(section 4.1)
|
||
.Rm 6 4.1
|
||
for more information.
|
||
.IP .PRECIOUS \n(pw
|
||
.Ix 0 def .PRECIOUS target
|
||
.Ix 0 ref .PRECIOUS attribute
|
||
.Ix 0 ref attributes .PRECIOUS
|
||
Similar to
|
||
.CW .IGNORE ,
|
||
this gives the
|
||
.CW .PRECIOUS
|
||
attribute to each source on the dependency line, unless there are no
|
||
sources, in which case the
|
||
.CW .PRECIOUS
|
||
attribute is given to every target in the file.
|
||
.IP .RECURSIVE \n(pw
|
||
.Ix 0 def .RECURSIVE
|
||
.Ix 0 ref attributes .MAKE
|
||
.Ix 0 ref .MAKE
|
||
This target applies the
|
||
.CW .MAKE
|
||
attribute to all its sources. It does nothing if you don't give it any sources.
|
||
.IP .SHELL \n(pw
|
||
.Ix 0 def .SHELL
|
||
PMake is not constrained to only using the Bourne shell to execute
|
||
the commands you put in the makefile. You can tell it some other shell
|
||
to use with this target. Check out
|
||
.B "A Shell is a Shell is a Shell"
|
||
(section 4.4)
|
||
.Rm 7 4.4
|
||
for more information.
|
||
.IP .SILENT \n(pw
|
||
.Ix 0 def .SILENT target
|
||
.Ix 0 ref .SILENT attribute
|
||
.Ix 0 ref attributes .SILENT
|
||
When you use
|
||
.CW .SILENT
|
||
as a target, it applies the
|
||
.CW .SILENT
|
||
attribute to each of its sources. If there are no sources on the
|
||
dependency line, then it is as if you gave PMake the
|
||
.B \-s
|
||
flag and no commands will be echoed.
|
||
.IP .SUFFIXES \n(pw
|
||
.Ix 0 def .SUFFIXES
|
||
This is used to give new file suffixes for PMake to handle. Each
|
||
source is a suffix PMake should recognize. If you give a
|
||
.CW .SUFFIXES
|
||
dependency line with no sources, PMake will forget about all the
|
||
suffixes it knew (this also nukes the null suffix).
|
||
For those targets that need to have suffixes defined, this is how you do it.
|
||
.LP
|
||
In addition to these targets, a line of the form
|
||
.DS
|
||
\fIattribute\fP : \fIsources\fP
|
||
.DE
|
||
applies the
|
||
.I attribute
|
||
to all the targets listed as
|
||
.I sources .
|
||
.xH 2 Modifying Variable Expansion
|
||
.LP
|
||
.Ix 0 def variable expansion modified
|
||
.Ix 0 ref variable expansion
|
||
.Ix 0 def variable modifiers
|
||
Variables need not always be expanded verbatim. PMake defines several
|
||
modifiers that may be applied to a variable's value before it is
|
||
expanded. You apply a modifier by placing it after the variable name
|
||
with a colon between the two, like so:
|
||
.DS
|
||
${\fIVARIABLE\fP:\fImodifier\fP}
|
||
.DE
|
||
Each modifier is a single character followed by something specific to
|
||
the modifier itself.
|
||
You may apply as many modifiers as you want \*- each one is applied to
|
||
the result of the previous and is separated from the previous by
|
||
another colon.
|
||
.LP
|
||
There are seven ways to modify a variable's expansion, most of which
|
||
come from the C shell variable modification characters:
|
||
.RS
|
||
.IP "M\fIpattern\fP"
|
||
.Ix 0 def :M
|
||
.Ix 0 def modifier match
|
||
This is used to select only those words (a word is a series of
|
||
characters that are neither spaces nor tabs) that match the given
|
||
.I pattern .
|
||
The pattern is a wildcard pattern like that used by the shell, where
|
||
.CW *
|
||
means 0 or more characters of any sort;
|
||
.CW ?
|
||
is any single character;
|
||
.CW [abcd]
|
||
matches any single character that is either `a', `b', `c' or `d'
|
||
(there may be any number of characters between the brackets);
|
||
.CW [0-9]
|
||
matches any single character that is between `0' and `9' (i.e. any
|
||
digit. This form may be freely mixed with the other bracket form), and
|
||
`\\' is used to escape any of the characters `*', `?', `[' or `:',
|
||
leaving them as regular characters to match themselves in a word.
|
||
For example, the system makefile
|
||
.CW <makedepend.mk>
|
||
uses
|
||
.CW "$(CFLAGS:M-[ID]*)" '' ``
|
||
to extract all the
|
||
.CW \-I
|
||
and
|
||
.CW \-D
|
||
flags that would be passed to the C compiler. This allows it to
|
||
properly locate include files and generate the correct dependencies.
|
||
.IP "N\fIpattern\fP"
|
||
.Ix 0 def :N
|
||
.Ix 0 def modifier nomatch
|
||
This is identical to
|
||
.CW :M
|
||
except it substitutes all words that don't match the given pattern.
|
||
.IP "S/\fIsearch-string\fP/\fIreplacement-string\fP/[g]"
|
||
.Ix 0 def :S
|
||
.Ix 0 def modifier substitute
|
||
Causes the first occurrence of
|
||
.I search-string
|
||
in the variable to be replaced by
|
||
.I replacement-string ,
|
||
unless the
|
||
.CW g
|
||
flag is given at the end, in which case all occurrences of the string
|
||
are replaced. The substitution is performed on each word in the
|
||
variable in turn. If
|
||
.I search-string
|
||
begins with a
|
||
.CW ^ ,
|
||
the string must match starting at the beginning of the word. If
|
||
.I search-string
|
||
ends with a
|
||
.CW $ ,
|
||
the string must match to the end of the word (these two may be
|
||
combined to force an exact match). If a backslash precedes these two
|
||
characters, however, they lose their special meaning. Variable
|
||
expansion also occurs in the normal fashion inside both the
|
||
.I search-string
|
||
and the
|
||
.I replacement-string ,
|
||
.B except
|
||
that a backslash is used to prevent the expansion of a
|
||
.CW $ ,
|
||
not another dollar sign, as is usual.
|
||
Note that
|
||
.I search-string
|
||
is just a string, not a pattern, so none of the usual
|
||
regular-expression/wildcard characters have any special meaning save
|
||
.CW ^
|
||
and
|
||
.CW $ .
|
||
In the replacement string,
|
||
the
|
||
.CW &
|
||
character is replaced by the
|
||
.I search-string
|
||
unless it is preceded by a backslash.
|
||
You are allowed to use any character except
|
||
colon or exclamation point to separate the two strings. This so-called
|
||
delimiter character may be placed in either string by preceeding it
|
||
with a backslash.
|
||
.IP T
|
||
.Ix 0 def :T
|
||
.Ix 0 def modifier tail
|
||
Replaces each word in the variable expansion by its last
|
||
component (its ``tail''). For example, given
|
||
.DS
|
||
OBJS = ../lib/a.o b /usr/lib/libm.a
|
||
TAILS = $(OBJS:T)
|
||
.DE
|
||
the variable
|
||
.CW TAILS
|
||
would expand to
|
||
.CW "a.o b libm.a" .'' ``
|
||
.IP H
|
||
.Ix 0 def :H
|
||
.Ix 0 def modifier head
|
||
This is similar to
|
||
.CW :T ,
|
||
except that every word is replaced by everything but the tail (the
|
||
``head''). Using the same definition of
|
||
.CW OBJS ,
|
||
the string
|
||
.CW "$(OBJS:H)" '' ``
|
||
would expand to
|
||
.CW "../lib /usr/lib" .'' ``
|
||
Note that the final slash on the heads is removed and
|
||
anything without a head is replaced by the empty string.
|
||
.IP E
|
||
.Ix 0 def :E
|
||
.Ix 0 def modifier extension
|
||
.Ix 0 def modifier suffix
|
||
.Ix 0 ref suffix "variable modifier"
|
||
.CW :E
|
||
replaces each word by its suffix (``extension''). So
|
||
.CW "$(OBJS:E)" '' ``
|
||
would give you
|
||
.CW ".o .a" .'' ``
|
||
.IP R
|
||
.Ix 0 def :R
|
||
.Ix 0 def modifier root
|
||
.Ix 0 def modifier base
|
||
This replaces each word by everything but the suffix (the ``root'' of
|
||
the word).
|
||
.CW "$(OBJS:R)" '' ``
|
||
expands to ``
|
||
.CW "../lib/a b /usr/lib/libm" .''
|
||
.RE
|
||
.LP
|
||
In addition, the System V style of substitution is also supported.
|
||
This looks like:
|
||
.DS
|
||
$(\fIVARIABLE\fP:\fIsearch-string\fP=\fIreplacement\fP)
|
||
.DE
|
||
It must be the last modifier in the chain. The search is anchored at
|
||
the end of each word, so only suffixes or whole words may be replaced.
|
||
.xH 2 More on Debugging
|
||
.xH 2 More Exercises
|
||
.IP (3.1)
|
||
You've got a set programs, each of which is created from its own
|
||
assembly-language source file (suffix
|
||
.CW .asm ).
|
||
Each program can be assembled into two versions, one with error-checking
|
||
code assembled in and one without. You could assemble them into files
|
||
with different suffixes
|
||
.CW .eobj \& (
|
||
and
|
||
.CW .obj ,
|
||
for instance), but your linker only understands files that end in
|
||
.CW .obj .
|
||
To top it all off, the final executables
|
||
.I must
|
||
have the suffix
|
||
.CW .exe .
|
||
How can you still use transformation rules to make your life easier
|
||
(Hint: assume the error-checking versions have
|
||
.CW ec
|
||
tacked onto their prefix)?
|
||
.IP (3.2)
|
||
Assume, for a moment or two, you want to perform a sort of
|
||
``indirection'' by placing the name of a variable into another one,
|
||
then you want to get the value of the first by expanding the second
|
||
somehow. Unfortunately, PMake doesn't allow constructs like
|
||
.DS I
|
||
$($(FOO))
|
||
.DE
|
||
What do you do? Hint: no further variable expansion is performed after
|
||
modifiers are applied, thus if you cause a $ to occur in the
|
||
expansion, that's what will be in the result.
|
||
.xH 1 PMake for Gods
|
||
.LP
|
||
This chapter is devoted to those facilities in PMake that allow you to
|
||
do a great deal in a makefile with very little work, as well as do
|
||
some things you couldn't do in Make without a great deal of work (and
|
||
perhaps the use of other programs). The problem with these features,
|
||
is they must be handled with care, or you will end up with a mess.
|
||
.LP
|
||
Once more, I assume a greater familiarity with
|
||
.UX
|
||
or Sprite than I did in the previous two chapters.
|
||
.xH 2 Search Paths
|
||
.Rd 6
|
||
.LP
|
||
PMake supports the dispersal of files into multiple directories by
|
||
allowing you to specify places to look for sources with
|
||
.CW .PATH
|
||
targets in the makefile. The directories you give as sources for these
|
||
targets make up a ``search path.'' Only those files used exclusively
|
||
as sources are actually sought on a search path, the assumption being
|
||
that anything listed as a target in the makefile can be created by the
|
||
makefile and thus should be in the current directory.
|
||
.LP
|
||
There are two types of search paths
|
||
in PMake: one is used for all types of files (including included
|
||
makefiles) and is specified with a plain
|
||
.CW .PATH
|
||
target (e.g.
|
||
.CW ".PATH : RCS" ''), ``
|
||
while the other is specific to a certain type of file, as indicated by
|
||
the file's suffix. A specific search path is indicated by immediately following
|
||
the
|
||
.CW .PATH
|
||
with the suffix of the file. For instance
|
||
.DS
|
||
\&.PATH.h : /sprite/lib/include /sprite/att/lib/include
|
||
.DE
|
||
would tell PMake to look in the directories
|
||
.CW /sprite/lib/include
|
||
and
|
||
.CW /sprite/att/lib/include
|
||
for any files whose suffix is
|
||
.CW .h .
|
||
.LP
|
||
The current directory is always consulted first to see if a file
|
||
exists. Only if it cannot be found there are the directories in the
|
||
specific search path, followed by those in the general search path,
|
||
consulted.
|
||
.LP
|
||
A search path is also used when expanding wildcard characters. If the
|
||
pattern has a recognizable suffix on it, the path for that suffix will
|
||
be used for the expansion. Otherwise the default search path is employed.
|
||
.LP
|
||
When a file is found in some directory other than the current one, all
|
||
local variables that would have contained the target's name
|
||
.CW .ALLSRC , (
|
||
and
|
||
.CW .IMPSRC )
|
||
will instead contain the path to the file, as found by PMake.
|
||
Thus if you have a file
|
||
.CW ../lib/mumble.c
|
||
and a makefile
|
||
.DS
|
||
\&.PATH.c : ../lib
|
||
mumble : mumble.c
|
||
$(CC) -o $(.TARGET) $(.ALLSRC)
|
||
.DE
|
||
the command executed to create
|
||
.CW mumble
|
||
would be
|
||
.CW "cc -o mumble ../lib/mumble.c" .'' ``
|
||
(As an aside, the command in this case isn't strictly necessary, since
|
||
it will be found using transformation rules if it isn't given. This is because
|
||
.CW .out
|
||
is the null suffix by default and a transformation exists from
|
||
.CW .c
|
||
to
|
||
.CW .out .
|
||
Just thought I'd throw that in.)
|
||
.LP
|
||
If a file exists in two directories on the same search path, the file
|
||
in the first directory on the path will be the one PMake uses. So if
|
||
you have a large system spread over many directories, it would behoove
|
||
you to follow a naming convention that avoids such conflicts.
|
||
.LP
|
||
Something you should know about the way search paths are implemented
|
||
is that each directory is read, and its contents cached, exactly once
|
||
\&\*- when it is first encountered \*- so any changes to the
|
||
directories while PMake is running will not be noted when searching
|
||
for implicit sources, nor will they be found when PMake attempts to
|
||
discover when the file was last modified, unless the file was created in the
|
||
current directory. While people have suggested that PMake should read
|
||
the directories each time, my experience suggests that the caching seldom
|
||
causes problems. In addition, not caching the directories slows things
|
||
down enormously because of PMake's attempts to apply transformation
|
||
rules through non-existent files \*- the number of extra file-system
|
||
searches is truly staggering, especially if many files without
|
||
suffixes are used and the null suffix isn't changed from
|
||
.CW .out .
|
||
.xH 2 Archives and Libraries
|
||
.LP
|
||
.UX
|
||
and Sprite allow you to merge files into an archive using the
|
||
.CW ar
|
||
command. Further, if the files are relocatable object files, you can
|
||
run
|
||
.CW ranlib
|
||
on the archive and get yourself a library that you can link into any
|
||
program you want. The main problem with archives is they double the
|
||
space you need to store the archived files, since there's one copy in
|
||
the archive and one copy out by itself. The problem with libraries is
|
||
you usually think of them as
|
||
.CW -lm
|
||
rather than
|
||
.CW /usr/lib/libm.a
|
||
and the linker thinks they're out-of-date if you so much as look at
|
||
them.
|
||
.LP
|
||
PMake solves the problem with archives by allowing you to tell it to
|
||
examine the files in the archives (so you can remove the individual
|
||
files without having to regenerate them later). To handle the problem
|
||
with libraries, PMake adds an additional way of deciding if a library
|
||
is out-of-date:
|
||
.IP \(bu 2
|
||
If the table of contents is older than the library, or is missing, the
|
||
library is out-of-date.
|
||
.LP
|
||
A library is any target that looks like
|
||
.CW \-l name'' ``
|
||
or that ends in a suffix that was marked as a library using the
|
||
.CW .LIBS
|
||
target.
|
||
.CW .a
|
||
is so marked in the system makefile.
|
||
.LP
|
||
Members of an archive are specified as
|
||
``\fIarchive\fP(\fImember\fP[ \fImember\fP...])''.
|
||
Thus
|
||
.CW libdix.a(window.o) '' ``'
|
||
specifies the file
|
||
.CW window.o
|
||
in the archive
|
||
.CW libdix.a .
|
||
You may also use wildcards to specify the members of the archive. Just
|
||
remember that most the wildcard characters will only find
|
||
.I existing
|
||
files.
|
||
.LP
|
||
A file that is a member of an archive is treated specially. If the
|
||
file doesn't exist, but it is in the archive, the modification time
|
||
recorded in the archive is used for the file when determining if the
|
||
file is out-of-date. When figuring out how to make an archived member target
|
||
(not the file itself, but the file in the archive \*- the
|
||
\fIarchive\fP(\fImember\fP) target), special care is
|
||
taken with the transformation rules, as follows:
|
||
.IP \(bu 2
|
||
\&\fIarchive\fP(\fImember\fP) is made to depend on \fImember\fP.
|
||
.IP \(bu 2
|
||
The transformation from the \fImember\fP's suffix to the
|
||
\fIarchive\fP's suffix is applied to the \fIarchive\fP(\fImember\fP) target.
|
||
.IP \(bu 2
|
||
The \fIarchive\fP(\fImember\fP)'s
|
||
.CW .TARGET
|
||
variable is set to the name of the \fImember\fP if \fImember\fP is
|
||
actually a target, or the path to the member file if \fImember\fP is
|
||
only a source.
|
||
.IP \(bu 2
|
||
The
|
||
.CW .ARCHIVE
|
||
variable for the \fIarchive\fP(\fImember\fP) target is set to the name
|
||
of the \fIarchive\fP.
|
||
.Ix 0 def variable local .ARCHIVE
|
||
.Ix 0 def .ARCHIVE
|
||
.IP \(bu 2
|
||
The
|
||
.CW .MEMBER
|
||
variable is set to the actual string inside the parentheses. In most
|
||
cases, this will be the same as the
|
||
.CW .TARGET
|
||
variable.
|
||
.Ix 0 def variable local .MEMBER
|
||
.Ix 0 def .MEMBER
|
||
.IP \(bu 2
|
||
The \fIarchive\fP(\fImember\fP)'s place in the local variables of the
|
||
targets that depend on it is taken by the value of its
|
||
.CW .TARGET
|
||
variable.
|
||
.LP
|
||
Thus, a program library could be created with the following makefile:
|
||
.DS
|
||
\&.o.a :
|
||
...
|
||
rm -f $(.TARGET:T)
|
||
OBJS = obj1.o obj2.o obj3.o
|
||
libprog.a : libprog.a($(OBJS))
|
||
ar cru $(.TARGET) $(.OODATE)
|
||
ranlib $(.TARGET)
|
||
.DE
|
||
This will cause the three object files to be compiled (if the
|
||
corresponding source files were modified after the object file or, if
|
||
that doesn't exist, the archived object file), the out-of-date ones
|
||
archived in
|
||
.CW libprog.a ,
|
||
a table of contents placed in the archive and the newly-archived
|
||
object files to be removed.
|
||
.LP
|
||
All this is used in the
|
||
.CW makelib.mk
|
||
system makefile to create a single library with ease. This makefile
|
||
looks like this:
|
||
.DS
|
||
.SM
|
||
#
|
||
# Rules for making libraries. The object files that make up the library
|
||
# are removed once they are archived.
|
||
#
|
||
# To make several libraries in parallel, you should define the variable
|
||
# "many_libraries". This will serialize the invocations of ranlib.
|
||
#
|
||
# To use, do something like this:
|
||
#
|
||
# OBJECTS = <files in the library>
|
||
#
|
||
# fish.a: fish.a($(OBJECTS)) MAKELIB
|
||
#
|
||
#
|
||
|
||
#ifndef _MAKELIB_MK
|
||
_MAKELIB_MK =
|
||
|
||
#include <po.mk>
|
||
|
||
\&.po.a .o.a :
|
||
...
|
||
rm -f $(.MEMBER)
|
||
|
||
ARFLAGS ?= crl
|
||
|
||
#
|
||
# Re-archive the out-of-date members and recreate the library's table of
|
||
# contents using ranlib. If many_libraries is defined, put the ranlib
|
||
# off til the end so many libraries can be made at once.
|
||
#
|
||
MAKELIB : .USE .PRECIOUS
|
||
ar $(ARFLAGS) $(.TARGET) $(.OODATE)
|
||
#ifndef no_ranlib
|
||
# ifdef many_libraries
|
||
...
|
||
# endif many_libraries
|
||
ranlib $(.TARGET)
|
||
#endif no_ranlib
|
||
|
||
#endif _MAKELIB_MK
|
||
.DE
|
||
.xH 2 On the Condition...
|
||
.Rd 1
|
||
.LP
|
||
Like the C compiler before it, PMake allows you to configure the makefile,
|
||
based on the current environment, using conditional statements. A
|
||
conditional looks like this:
|
||
.DS
|
||
#if \fIboolean expression\fP
|
||
\fIlines\fP
|
||
#elif \fIanother boolean expression\fP
|
||
\fImore lines\fP
|
||
#else
|
||
\fIstill more lines\fP
|
||
#endif
|
||
.DE
|
||
They may be nested to a maximum depth of 30 and may occur anywhere
|
||
(except in a comment, of course). The
|
||
.CW # '' ``
|
||
must the very first character on the line.
|
||
.LP
|
||
Each
|
||
.I "boolean expression"
|
||
is made up of terms that look like function calls, the standard C
|
||
boolean operators
|
||
.CW && ,
|
||
.CW || ,
|
||
and
|
||
.CW ! ,
|
||
and the standard relational operators
|
||
.CW == ,
|
||
.CW != ,
|
||
.CW > ,
|
||
.CW >= ,
|
||
.CW < ,
|
||
and
|
||
.CW <= ,
|
||
with
|
||
.CW ==
|
||
and
|
||
.CW !=
|
||
being overloaded to allow string comparisons as well.
|
||
.CW &&
|
||
represents logical AND;
|
||
.CW ||
|
||
is logical OR and
|
||
.CW !
|
||
is logical NOT. The arithmetic and string operators take precedence
|
||
over all three of these operators, while NOT takes precedence over
|
||
AND, which takes precedence over OR. This precedence may be
|
||
overridden with parentheses, and an expression may be parenthesized to
|
||
your heart's content. Each term looks like a call on one of four
|
||
functions:
|
||
.nr pw 9
|
||
.Ix 0 def make
|
||
.Ix 0 def conditional make
|
||
.Ix 0 def if make
|
||
.IP make \n(pw
|
||
The syntax is
|
||
.CW make( \fItarget\fP\c
|
||
.CW )
|
||
where
|
||
.I target
|
||
is a target in the makefile. This is true if the given target was
|
||
specified on the command line, or as the source for a
|
||
.CW .MAIN
|
||
target (note that the sources for
|
||
.CW .MAIN
|
||
are only used if no targets were given on the command line).
|
||
.IP defined \n(pw
|
||
.Ix 0 def defined
|
||
.Ix 0 def conditional defined
|
||
.Ix 0 def if defined
|
||
The syntax is
|
||
.CW defined( \fIvariable\fP\c
|
||
.CW )
|
||
and is true if
|
||
.I variable
|
||
is defined. Certain variables are defined in the system makefile that
|
||
identify the system on which PMake is being run.
|
||
.IP exists \n(pw
|
||
.Ix 0 def exists
|
||
.Ix 0 def conditional exists
|
||
.Ix 0 def if exists
|
||
The syntax is
|
||
.CW exists( \fIfile\fP\c
|
||
.CW )
|
||
and is true if the file can be found on the global search path (i.e.
|
||
that defined by
|
||
.CW .PATH
|
||
targets, not by
|
||
.CW .PATH \fIsuffix\fP
|
||
targets).
|
||
.IP empty \n(pw
|
||
.Ix 0 def empty
|
||
.Ix 0 def conditional empty
|
||
.Ix 0 def if empty
|
||
This syntax is much like the others, except the string inside the
|
||
parentheses is of the same form as you would put between parentheses
|
||
when expanding a variable, complete with modifiers and everything. The
|
||
function returns true if the resulting string is empty (NOTE: an undefined
|
||
variable in this context will cause at the very least a warning
|
||
message about a malformed conditional, and at the worst will cause the
|
||
process to stop once it has read the makefile. If you want to check
|
||
for a variable being defined or empty, use the expression
|
||
.CW !defined( \fIvar\fP\c ``
|
||
.CW ") || empty(" \fIvar\fP\c
|
||
.CW ) ''
|
||
as the definition of
|
||
.CW ||
|
||
will prevent the
|
||
.CW empty()
|
||
from being evaluated and causing an error, if the variable is
|
||
undefined). This can be used to see if a variable contains a given
|
||
word, for example:
|
||
.DS
|
||
#if !empty(\fIvar\fP:M\fIword\fP)
|
||
.DE
|
||
.LP
|
||
The arithmetic and string operators may only be used to test the value
|
||
of a variable. The lefthand side must contain the variable expansion,
|
||
while the righthand side contains either a string, enclosed in
|
||
double-quotes, or a number. The standard C numeric conventions (except
|
||
for specifying an octal number) apply to both sides. E.g.
|
||
.DS
|
||
#if $(OS) == 4.3
|
||
|
||
#if $(MACHINE) == "sun3"
|
||
|
||
#if $(LOAD_ADDR) < 0xc000
|
||
.DE
|
||
are all valid conditionals. In addition, the numeric value of a
|
||
variable can be tested as a boolean as follows:
|
||
.DS
|
||
#if $(LOAD)
|
||
.DE
|
||
would see if
|
||
.CW LOAD
|
||
contains a non-zero value and
|
||
.DS
|
||
#if !$(LOAD)
|
||
.DE
|
||
would test if
|
||
.CW LOAD
|
||
contains a zero value.
|
||
.LP
|
||
In addition to the bare
|
||
.CW #if ,'' ``
|
||
there are other forms that apply one of the first two functions to each
|
||
term. They are as follows:
|
||
.DS
|
||
ifdef \fRdefined\fP
|
||
ifndef \fR!defined\fP
|
||
ifmake \fRmake\fP
|
||
ifnmake \fR!make\fP
|
||
.DE
|
||
There are also the ``else if'' forms:
|
||
.CW elif ,
|
||
.CW elifdef ,
|
||
.CW elifndef ,
|
||
.CW elifmake ,
|
||
and
|
||
.CW elifnmake .
|
||
.LP
|
||
For instance, if you wish to create two versions of a program, one of which
|
||
is optimized (the production version) and the other of which is for debugging
|
||
(has symbols for dbx), you have two choices: you can create two
|
||
makefiles, one of which uses the
|
||
.CW \-g
|
||
flag for the compilation, while the other uses the
|
||
.CW \-O
|
||
flag, or you can use another target (call it
|
||
.CW debug )
|
||
to create the debug version. The construct below will take care of
|
||
this for you. I have also made it so defining the variable
|
||
.CW DEBUG
|
||
(say with
|
||
.CW "pmake -D DEBUG" )
|
||
will also cause the debug version to be made.
|
||
.DS
|
||
#if defined(DEBUG) || make(debug)
|
||
CFLAGS += -g
|
||
#else
|
||
CFLAGS += -O
|
||
#endif
|
||
.DE
|
||
There are, of course, problems with this approach. The most glaring
|
||
annoyance is that if you want to go from making a debug version to
|
||
making a production version, you have to remove all the object files,
|
||
or you will get some optimized and some debug versions in the same
|
||
program. Another annoyance is you have to be careful not to make two
|
||
targets that ``conflict'' because of some conditionals in the
|
||
makefile. For instance
|
||
.DS
|
||
#if make(print)
|
||
FORMATTER = ditroff -Plaser_printer
|
||
#endif
|
||
#if make(draft)
|
||
FORMATTER = nroff -Pdot_matrix_printer
|
||
#endif
|
||
.DE
|
||
would wreak havoc if you tried
|
||
.CW "pmake draft print" '' ``
|
||
since you would use the same formatter for each target. As I said,
|
||
this all gets somewhat complicated.
|
||
.xH 2 A Shell is a Shell is a Shell
|
||
.Rd 7
|
||
.LP
|
||
In normal operation, the Bourne Shell (better known as
|
||
.CW sh '') ``
|
||
is used to execute the commands to re-create targets. PMake also allows you
|
||
to specify a different shell for it to use when executing these
|
||
commands. There are several things PMake must know about the shell you
|
||
wish to use. These things are specified as the sources for the
|
||
.CW .SHELL
|
||
.Ix 0 ref .SHELL
|
||
.Ix 0 ref target .SHELL
|
||
target by keyword, as follows:
|
||
.IP "\fBpath=\fP\fIpath\fP"
|
||
PMake needs to know where the shell actually resides, so it can
|
||
execute it. If you specify this and nothing else, PMake will use the
|
||
last component of the path and look in its table of the shells it
|
||
knows and use the specification it finds, if any. Use this if you just
|
||
want to use a different version of the Bourne or C Shell (yes, PMake knows
|
||
how to use the C Shell too).
|
||
.IP "\fBname=\fP\fIname\fP"
|
||
This is the name by which the shell is to be known. It is a single
|
||
word and, if no other keywords are specified (other than
|
||
.B path ),
|
||
it is the name by which PMake attempts to find a specification for
|
||
it (as mentioned above). You can use this if you would just rather use
|
||
the C Shell than the Bourne Shell
|
||
.CW ".SHELL: name=csh" '' (``
|
||
will do it).
|
||
.IP "\fBquiet=\fP\fIecho-off command\fP"
|
||
As mentioned before, PMake actually controls whether commands are
|
||
printed by introducing commands into the shell's input stream. This
|
||
keyword, and the next two, control what those commands are. The
|
||
.B quiet
|
||
keyword is the command used to turn echoing off. Once it is turned
|
||
off, echoing is expected to remain off until the echo-on command is given.
|
||
.IP "\fBecho=\fP\fIecho-on command\fP"
|
||
The command PMake should give to turn echoing back on again.
|
||
.IP "\fBfilter=\fP\fIprinted echo-off command\fP"
|
||
Many shells will echo the echo-off command when it is given. This
|
||
keyword tells PMake in what format the shell actually prints the
|
||
echo-off command. Wherever PMake sees this string in the shell's
|
||
output, it will delete it and any following whitespace, up to and
|
||
including the next newline. See the example at the end of this section
|
||
for more details.
|
||
.IP "\fBechoFlag=\fP\fIflag to turn echoing on\fP"
|
||
Unless a target has been marked
|
||
.CW .SILENT ,
|
||
PMake wants to start the shell running with echoing on. To do this, it
|
||
passes this flag to the shell as one of its arguments. If either this
|
||
or the next flag begins with a `\-', the flags will be passed to the
|
||
shell as separate arguments. Otherwise, the two will be concatenated
|
||
(if they are used at the same time, of course).
|
||
.IP "\fBerrFlag=\fP\fIflag to turn error checking on\fP"
|
||
Likewise, unless a target is marked
|
||
.CW .IGNORE ,
|
||
PMake wishes error-checking to be on from the very start. To this end,
|
||
it will pass this flag to the shell as an argument. The same rules for
|
||
an initial `\-' apply as for the
|
||
.B echoFlag .
|
||
.IP "\fBcheck=\fP\fIcommand to turn error checking on\fP"
|
||
Just as for echo-control, error-control is achieved by inserting
|
||
commands into the shell's input stream. This is the command to make
|
||
the shell check for errors. It also serves another purpose if the
|
||
shell doesn't have error-control as commands, but I'll get into that
|
||
in a minute. Again, once error checking has been turned on, it is
|
||
expected to remain on until it is turned off again.
|
||
.IP "\fBignore=\fP\fIcommand to turn error checking off\fP"
|
||
This is the command PMake uses to turn error checking off. It has
|
||
another use if the shell doesn't do error-control, but I'll tell you
|
||
about that.\|.\|.\|now.
|
||
.IP "\fBhasErrCtl=\fP\fIyes or no\fP"
|
||
This takes a value that is either
|
||
.B yes
|
||
or
|
||
.B no .
|
||
Now you might think that the existence of the
|
||
.B check
|
||
and
|
||
.B ignore
|
||
keywords would be enough to tell PMake if the shell can do
|
||
error-control, but you'd be wrong. If
|
||
.B hasErrCtl
|
||
is
|
||
.B yes ,
|
||
PMake uses the check and ignore commands in a straight-forward manner.
|
||
If this is
|
||
.B no ,
|
||
however, their use is rather different. In this case, the check
|
||
command is used as a template, in which the string
|
||
.B %s
|
||
is replaced by the command that's about to be executed, to produce a
|
||
command for the shell that will echo the command to be executed. The
|
||
ignore command is also used as a template, again with
|
||
.B %s
|
||
replaced by the command to be executed, to produce a command that will
|
||
execute the command to be executed and ignore any error it returns.
|
||
When these strings are used as templates, you must provide newline(s)
|
||
.CW \en '') (``
|
||
in the appropriate place(s).
|
||
.LP
|
||
The strings that follow these keywords may be enclosed in single or
|
||
double quotes (the quotes will be stripped off) and may contain the
|
||
usual C backslash-characters (\en is newline, \er is return, \eb is
|
||
backspace, \e' escapes a single-quote inside single-quotes, \e"
|
||
escapes a double-quote inside double-quotes). Now for an example.
|
||
.LP
|
||
This is actually the contents of the
|
||
.CW <shx.mk>
|
||
system makefile, and causes PMake to use the Bourne Shell in such a
|
||
way that each command is printed as it is executed. That is, if more
|
||
than one command is given on a line, each will be printed separately.
|
||
Similarly, each time the body of a loop is executed, the commands
|
||
within that loop will be printed, etc. The specification runs like
|
||
this:
|
||
.DS
|
||
#
|
||
# This is a shell specification to have the Bourne shell echo
|
||
# the commands just before executing them, rather than when it reads
|
||
# them. Useful if you want to see how variables are being expanded, etc.
|
||
#
|
||
\&.SHELL : path=/bin/sh \e
|
||
quiet="set -" \e
|
||
echo="set -x" \e
|
||
filter="+ set - " \e
|
||
echoFlag=x \e
|
||
errFlag=e \e
|
||
hasErrCtl=yes \e
|
||
check="set -e" \e
|
||
ignore="set +e"
|
||
.DE
|
||
.LP
|
||
It tells PMake the following:
|
||
.Bp
|
||
The shell is located in the file
|
||
.CW /bin/sh .
|
||
It need not tell PMake that the name of the shell is
|
||
.CW sh
|
||
as PMake can figure that out for itself (it's the last component of
|
||
the path).
|
||
.Bp
|
||
The command to stop echoing is
|
||
.CW "set -" .
|
||
.Bp
|
||
The command to start echoing is
|
||
.CW "set -x" .
|
||
.Bp
|
||
When the echo off command is executed, the shell will print
|
||
.CW "+ set - "
|
||
(The `+' comes from using the
|
||
.CW \-x
|
||
flag (rather than the
|
||
.CW \-v
|
||
flag PMake usually uses)). PMake will remove all occurrences of this
|
||
string from the output, so you don't notice extra commands you didn't
|
||
put there.
|
||
.Bp
|
||
The flag the Bourne Shell will take to start echoing in this way is
|
||
the
|
||
.CW \-x
|
||
flag. The Bourne Shell will only take its flag arguments concatenated
|
||
as its first argument, so neither this nor the
|
||
.B errFlag
|
||
specification begins with a \-.
|
||
.Bp
|
||
The flag to use to turn error-checking on from the start is
|
||
.CW \-e .
|
||
.Bp
|
||
The shell can turn error-checking on and off, and the commands to do
|
||
so are
|
||
.CW "set +e"
|
||
and
|
||
.CW "set -e" ,
|
||
respectively.
|
||
.LP
|
||
I should note that this specification is for Bourne Shells that are
|
||
not part of Berkeley
|
||
.UX ,
|
||
as shells from Berkeley don't do error control. You can get a similar
|
||
effect, however, by changing the last three lines to be:
|
||
.DS
|
||
hasErrCtl=no \e
|
||
check="echo \e"+ %s\e"\en" \e
|
||
ignore="sh -c '%s || exit 0\en"
|
||
.DE
|
||
.LP
|
||
This will cause PMake to execute the two commands
|
||
.DS
|
||
echo "+ \fIcmd\fP"
|
||
sh -c '\fIcmd\fP || true'
|
||
.DE
|
||
for each command for which errors are to be ignored. (In case you are
|
||
wondering, the thing for
|
||
.CW ignore
|
||
tells the shell to execute another shell without error checking on and
|
||
always exit 0, since the
|
||
.B ||
|
||
causes the
|
||
.CW "exit 0"
|
||
to be executed only if the first command exited non-zero, and if the
|
||
first command exited zero, the shell will also exit zero, since that's
|
||
the last command it executed).
|
||
.xH 2 Compatibility
|
||
.Ix 0 ref compatibility
|
||
.LP
|
||
There are three (well, 3 \(12) levels of backwards-compatibility built
|
||
into PMake. Most makefiles will need none at all. Some may need a
|
||
little bit of work to operate correctly when run in parallel. Each
|
||
level encompasses the previous levels (e.g.
|
||
.B \-B
|
||
(one shell per command) implies
|
||
.B \-V )
|
||
The three levels are described in the following three sections.
|
||
.xH 3 DEFCON 3 \*- Variable Expansion
|
||
.Ix 0 ref compatibility
|
||
.LP
|
||
As noted before, PMake will not expand a variable unless it knows of a
|
||
value for it. This can cause problems for makefiles that expect to
|
||
leave variables undefined except in special circumstances (e.g. if
|
||
more flags need to be passed to the C compiler or the output from a
|
||
text processor should be sent to a different printer). If the
|
||
variables are enclosed in curly braces
|
||
.CW ${PRINTER} ''), (``
|
||
the shell will let them pass. If they are enclosed in parentheses,
|
||
however, the shell will declare a syntax error and the make will come
|
||
to a grinding halt.
|
||
.LP
|
||
You have two choices: change the makefile to define the variables
|
||
(their values can be overridden on the command line, since that's
|
||
where they would have been set if you used Make, anyway) or always give the
|
||
.B \-V
|
||
flag (this can be done with the
|
||
.CW .MAKEFLAGS
|
||
target, if you want).
|
||
.xH 3 DEFCON 2 \*- The Number of the Beast
|
||
.Ix 0 ref compatibility
|
||
.LP
|
||
Then there are the makefiles that expect certain commands, such as
|
||
changing to a different directory, to not affect other commands in a
|
||
target's creation script. You can solve this is either by going
|
||
back to executing one shell per command (which is what the
|
||
.B \-B
|
||
flag forces PMake to do), which slows the process down a good bit and
|
||
requires you to use semicolons and escaped newlines for shell constructs, or
|
||
by changing the makefile to execute the offending command(s) in a subshell
|
||
(by placing the line inside parentheses), like so:
|
||
.DS
|
||
install :: .MAKE
|
||
(cd src; $(.PMAKE) install)
|
||
(cd lib; $(.PMAKE) install)
|
||
(cd man; $(.PMAKE) install)
|
||
.DE
|
||
.Ix 0 ref operator double-colon
|
||
.Ix 0 ref variable global .PMAKE
|
||
.Ix 0 ref .PMAKE
|
||
.Ix 0 ref .MAKE
|
||
.Ix 0 ref attribute .MAKE
|
||
This will always execute the three makes (even if the
|
||
.B \-n
|
||
flag was given) because of the combination of the ``::'' operator and
|
||
the
|
||
.CW .MAKE
|
||
attribute. Each command will change to the proper directory to perform
|
||
the install, leaving the main shell in the directory in which it started.
|
||
.xH 3 "DEFCON 1 \*- Imitation is the Not the Highest Form of Flattery"
|
||
.Ix 0 ref compatibility
|
||
.LP
|
||
The final category of makefile is the one where every command requires
|
||
input, the dependencies are incompletely specified, or you simply
|
||
cannot create more than one target at a time, as mentioned earlier. In
|
||
addition, you may not have the time or desire to upgrade the makefile
|
||
to run smoothly with PMake. If you are the conservative sort, this is
|
||
the compatibility mode for you. It is entered either by giving PMake
|
||
the
|
||
.B \-M
|
||
flag (for Make), or by executing PMake as
|
||
.CW make .'' ``
|
||
In either case, PMake performs things exactly like Make (while still
|
||
supporting most of the nice new features PMake provides). This
|
||
includes:
|
||
.IP \(bu 2
|
||
No parallel execution.
|
||
.IP \(bu 2
|
||
Targets are made in the exact order specified by the makefile. The
|
||
sources for each target are made in strict left-to-right order, etc.
|
||
.IP \(bu 2
|
||
A single Bourne shell is used to execute each command, thus the
|
||
shell's
|
||
.CW $$
|
||
variable is useless, changing directories doesn't work across command
|
||
lines, etc.
|
||
.IP \(bu 2
|
||
If no special characters exist in a command line, PMake will break the
|
||
command into words itself and execute the command directly, without
|
||
executing a shell first. The characters that cause PMake to execute a
|
||
shell are:
|
||
.CW # ,
|
||
.CW = ,
|
||
.CW | ,
|
||
.CW ^ ,
|
||
.CW ( ,
|
||
.CW ) ,
|
||
.CW { ,
|
||
.CW } ,
|
||
.CW ; ,
|
||
.CW & ,
|
||
.CW < ,
|
||
.CW > ,
|
||
.CW * ,
|
||
.CW ? ,
|
||
.CW [ ,
|
||
.CW ] ,
|
||
.CW : ,
|
||
.CW $ ,
|
||
.CW ` ,
|
||
and
|
||
.CW \e .
|
||
You should notice that these are all the characters that are given
|
||
special meaning by the shell (except
|
||
.CW '
|
||
and
|
||
.CW " ,
|
||
which PMake deals with all by its lonesome).
|
||
.IP \(bu 2
|
||
The use of the null suffix is turned off.
|
||
.Ix 0 ref "null suffix"
|
||
.Ix 0 ref suffix null
|
||
.xH 2 The Way Things Work
|
||
.LP
|
||
When PMake reads the makefile, it parses sources and targets into
|
||
nodes in a graph. The graph is directed only in the sense that PMake
|
||
knows which way is up. Each node contains not only links to all its
|
||
parents and children (the nodes that depend on it and those on which
|
||
it depends, respectively), but also a count of the number of its
|
||
children that have already been processed.
|
||
.LP
|
||
The most important thing to know about how PMake uses this graph is
|
||
that the traversal is breadth-first and occurs in two passes.
|
||
.LP
|
||
After PMake has parsed the makefile, it begins with the nodes the user
|
||
has told it to make (either on the command line, or via a
|
||
.CW .MAIN
|
||
target, or by the target being the first in the file not labeled with
|
||
the
|
||
.CW .NOTMAIN
|
||
attribute) placed in a queue. It continues to take the node off the
|
||
front of the queue, mark it as something that needs to be made, pass
|
||
the node to
|
||
.CW Suff_FindDeps
|
||
(mentioned earlier) to find any implicit sources for the node, and
|
||
place all the node's children that have yet to be marked at the end of
|
||
the queue. If any of the children is a
|
||
.CW .USE
|
||
rule, its attributes are applied to the parent, then its commands are
|
||
appended to the parent's list of commands and its children are linked
|
||
to its parent. The parent's unmade children counter is then decremented
|
||
(since the
|
||
.CW .USE
|
||
node has been processed). You will note that this allows a
|
||
.CW .USE
|
||
node to have children that are
|
||
.CW .USE
|
||
nodes and the rules will be applied in sequence.
|
||
If the node has no children, it is placed at the end of
|
||
another queue to be examined in the second pass. This process
|
||
continues until the first queue is empty.
|
||
.LP
|
||
At this point, all the leaves of the graph are in the examination
|
||
queue. PMake removes the node at the head of the queue and sees if it
|
||
is out-of-date. If it is, it is passed to a function that will execute
|
||
the commands for the node asynchronously. When the commands have
|
||
completed, all the node's parents have their unmade children counter
|
||
decremented and, if the counter is then 0, they are placed on the
|
||
examination queue. Likewise, if the node is up-to-date. Only those
|
||
parents that were marked on the downward pass are processed in this
|
||
way. Thus PMake traverses the graph back up to the nodes the user
|
||
instructed it to create. When the examination queue is empty and no
|
||
shells are running to create a target, PMake is finished.
|
||
.LP
|
||
Once all targets have been processed, PMake executes the commands
|
||
attached to the
|
||
.CW .END
|
||
target, either explicitly or through the use of an ellipsis in a shell
|
||
script. If there were no errors during the entire process but there
|
||
are still some targets unmade (PMake keeps a running count of how many
|
||
targets are left to be made), there is a cycle in the graph. PMake does
|
||
a depth-first traversal of the graph to find all the targets that
|
||
weren't made and prints them out one by one.
|
||
.xH 1 Answers to Exercises
|
||
.IP (3.1)
|
||
This is something of a trick question, for which I apologize. The
|
||
trick comes from the UNIX definition of a suffix, which PMake doesn't
|
||
necessarily share. You will have noticed that all the suffixes used in
|
||
this tutorial (and in UNIX in general) begin with a period
|
||
.CW .ms , (
|
||
.CW .c ,
|
||
etc.). Now, PMake's idea of a suffix is more like English's: it's the
|
||
characters at the end of a word. With this in mind, one possible
|
||
.Ix 0 def suffix
|
||
solution to this problem goes as follows:
|
||
.DS I
|
||
\&.SUFFIXES : ec.exe .exe ec.obj .obj .asm
|
||
ec.objec.exe .obj.exe :
|
||
link -o $(.TARGET) $(.IMPSRC)
|
||
\&.asmec.obj :
|
||
asm -o $(.TARGET) -DDO_ERROR_CHECKING $(.IMPSRC)
|
||
\&.asm.obj :
|
||
asm -o $(.TARGET) $(.IMPSRC)
|
||
.DE
|
||
.IP (3.2)
|
||
The trick to this one lies in the ``:='' variable-assignment operator
|
||
and the ``:S'' variable-expansion modifier.
|
||
.Ix 0 ref variable assignment expanded
|
||
.Ix 0 ref variable expansion modified
|
||
.Ix 0 ref modifier substitute
|
||
.Ix 0 ref :S
|
||
.Ix 0 ref :=
|
||
Basically what you want is to take the pointer variable, so to speak,
|
||
and transform it into an invocation of the variable at which it
|
||
points. You might try something like
|
||
.DS I
|
||
$(PTR:S/^/\e$(/:S/$/))
|
||
.DE
|
||
which places
|
||
.CW $( '' ``
|
||
at the front of the variable name and
|
||
.CW ) '' ``
|
||
at the end, thus transforming
|
||
.CW VAR ,'' ``
|
||
for example, into
|
||
.CW $(VAR) ,'' ``
|
||
which is just what we want. Unfortunately (as you know if you've tried
|
||
it), since, as it says in the hint, PMake does no further substitution
|
||
on the result of a modified expansion, that's \fIall\fP you get. The
|
||
solution is to make use of ``:='' to place that string into yet
|
||
another variable, then invoke the other variable directly:
|
||
.DS I
|
||
*PTR := $(PTR:S/^/\e$(/:S/$/)/)
|
||
.DE
|
||
You can then use
|
||
.CW $(*PTR) '' ``
|
||
to your heart's content.
|
||
.de Gp
|
||
.XP
|
||
\&\fB\\$1:\fP
|
||
..
|
||
.xH 1 Glossary of Jargon
|
||
.Gp "attribute"
|
||
A property given to a target that causes PMake to treat it differently.
|
||
.Gp "command script"
|
||
The lines immediately following a dependency line that specify
|
||
commands to execute to create each of the targets on the dependency
|
||
line. Each line in the command script must begin with a tab.
|
||
.Gp "command-line variable"
|
||
A variable defined in an argument when PMake is first executed.
|
||
Overrides all assignments to the same variable name in the makefile.
|
||
.Gp "conditional"
|
||
A construct much like that used in C that allows a makefile to be
|
||
configured on the fly based on the local environment, or on what is being
|
||
made by that invocation of PMake.
|
||
.Gp "creation script"
|
||
Commands used to create a target. See ``command script.''
|
||
.Gp "dependency"
|
||
The relationship between a source and a target. This comes in three
|
||
flavors, as indicated by the operator between the target and the
|
||
source. `:' gives a straight time-wise dependency (if the target is
|
||
older than the source, the target is out-of-date), while `!' provides
|
||
simply an ordering and always considers the target out-of-date. `::'
|
||
is much like `:', save it creates multiple instances of a target each
|
||
of which depends on its own list of sources.
|
||
.Gp "dynamic source"
|
||
This refers to a source that has a local variable invocation in it. It
|
||
allows a single dependency line to specify a different source for each
|
||
target on the line.
|
||
.Gp "global variable"
|
||
Any variable defined in a makefile. Takes precedence over variables
|
||
defined in the environment, but not over command-line or local variables.
|
||
.Gp "input graph"
|
||
What PMake constructs from a makefile. Consists of nodes made of the
|
||
targets in the makefile, and the links between them (the
|
||
dependencies). The links are directed (from source to target) and
|
||
there may not be any cycles (loops) in the graph.
|
||
.Gp "local variable"
|
||
A variable defined by PMake visible only in a target's shell script.
|
||
There are seven local variables, not all of which are defined for
|
||
every target:
|
||
.CW .TARGET ,
|
||
.CW .ALLSRC ,
|
||
.CW .OODATE ,
|
||
.CW .PREFIX ,
|
||
.CW .IMPSRC ,
|
||
.CW .ARCHIVE ,
|
||
and
|
||
.CW .MEMBER .
|
||
.CW .TARGET ,
|
||
.CW .PREFIX ,
|
||
.CW .ARCHIVE ,
|
||
and
|
||
.CW .MEMBER
|
||
may be used on dependency lines to create ``dynamic sources.''
|
||
.Gp "makefile"
|
||
A file that describes how a system is built. If you don't know what it
|
||
is after reading this tutorial.\|.\|.\|.
|
||
.Gp "modifier"
|
||
A letter, following a colon, used to alter how a variable is expanded.
|
||
It has no effect on the variable itself.
|
||
.Gp "operator"
|
||
What separates a source from a target (on a dependency line) and specifies
|
||
the relationship between the two. There are three:
|
||
.CW : ', `
|
||
.CW :: ', `
|
||
and
|
||
.CW ! '. `
|
||
.Gp "search path"
|
||
A list of directories in which a file should be sought. PMake's view
|
||
of the contents of directories in a search path does not change once
|
||
the makefile has been read. A file is sought on a search path only if
|
||
it is exclusively a source.
|
||
.Gp "shell"
|
||
A program to which commands are passed in order to create targets.
|
||
.Gp "source"
|
||
Anything to the right of an operator on a dependency line. Targets on
|
||
the dependency line are usually created from the sources.
|
||
.Gp "special target"
|
||
A target that causes PMake to do special things when it's encountered.
|
||
.Gp "suffix"
|
||
The tail end of a file name. Usually begins with a period,
|
||
.CW .c
|
||
or
|
||
.CW .ms ,
|
||
e.g.
|
||
.Gp "target"
|
||
A word to the left of the operator on a dependency line. More
|
||
generally, any file that PMake might create. A file may be (and often
|
||
is) both a target and a source (what it is depends on how PMake is
|
||
looking at it at the time \*- sort of like the wave/particle duality
|
||
of light, you know).
|
||
.Gp "transformation rule"
|
||
A special construct in a makefile that specifies how to create a file
|
||
of one type from a file of another, as indicated by their suffixes.
|
||
.Gp "variable expansion"
|
||
The process of substituting the value of a variable for a reference to
|
||
it. Expansion may be altered by means of modifiers.
|
||
.Gp "variable"
|
||
A place in which to store text that may be retrieved later. Also used
|
||
to define the local environment. Conditionals exist that test whether
|
||
a variable is defined or not.
|
||
.bp
|
||
.\" Output table of contents last, with an entry for the index, making
|
||
.\" sure to save and restore the last real page number for the index...
|
||
.nr @n \n(PN+1
|
||
.\" We are not generating an index
|
||
.\" .XS \n(@n
|
||
.\" Index
|
||
.\" .XE
|
||
.nr %% \n%
|
||
.PX
|
||
.nr % \n(%%
|