541 lines
15 KiB
Groff
541 lines
15 KiB
Groff
.\" $NetBSD: m4.1,v 1.23 2012/04/08 22:00:39 wiz Exp $
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.\" @(#) $OpenBSD: m4.1,v 1.64 2017/06/15 13:48:42 bcallah Exp $
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.\"
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.\" Copyright (c) 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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.\" Ozan Yigit at York University.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. Neither the name of the University nor the names of its contributors
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.\" 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
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.\" 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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.\" $FreeBSD$
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.\"
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.Dd April 8, 2021
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.Dt M4 1
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.Os
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.Sh NAME
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|
.Nm m4
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|
.Nd macro language processor
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|
.Sh SYNOPSIS
|
|
.Nm
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|
.Op Fl EgPs
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|
.Oo
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|
.Sm off
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|
.Fl D Ar name Op No = Ar value
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.Sm on
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.Oc
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|
.Op Fl d Ar flags
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|
.Op Fl I Ar dirname
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.Op Fl o Ar filename
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|
.Op Fl t Ar macro
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|
.Op Fl U Ns Ar name
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.Op Ar
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|
.Sh DESCRIPTION
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|
The
|
|
.Nm
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|
utility is a macro processor that can be used as a front end to any
|
|
language (e.g., C, ratfor, fortran, lex, and yacc).
|
|
If no input files are given,
|
|
.Nm
|
|
reads from the standard input,
|
|
otherwise files specified on the command line are
|
|
processed in the given order.
|
|
Input files can be regular files, files in the m4 include paths, or a
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|
single dash
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|
.Pq Sq - ,
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|
denoting standard input.
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|
.Nm
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|
writes
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|
the processed text to the standard output, unless told otherwise.
|
|
.Pp
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|
Macro calls have the form name(argument1[, argument2, ..., argumentN]).
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|
.Pp
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|
There cannot be any space following the macro name and the open
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|
parenthesis
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|
.Pq Sq \&( .
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|
If the macro name is not followed by an open
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|
parenthesis it is processed with no arguments.
|
|
.Pp
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|
Macro names consist of a leading alphabetic or underscore
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|
possibly followed by alphanumeric or underscore characters, e.g.,
|
|
valid macro names match the pattern
|
|
.Dq [a-zA-Z_][a-zA-Z0-9_]* .
|
|
.Pp
|
|
In arguments to macros, leading unquoted space, tab, and newline
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|
.Pq Sq \en
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|
characters are ignored.
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|
To quote strings, use left and right single quotes
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|
.Pq e.g., Sq \ \&this is a string with a leading space .
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|
You can change the quote characters with the
|
|
.Ic changequote
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|
built-in macro.
|
|
.Pp
|
|
Most built-ins do not make any sense without arguments, and hence are not
|
|
recognized as special when not followed by an open parenthesis.
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|
.Pp
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|
The options are as follows:
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|
.Bl -tag -width Ds
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|
.It Fl D Ns Ar name Ns Op = Ns Ar value
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|
Define the symbol
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|
.Ar name
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|
to have some value (or
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|
.Dv NULL ) .
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|
.It Fl d Ar "flags"
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|
Set trace flags.
|
|
.Ar flags
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|
may hold the following:
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|
.Bl -tag -width Ds
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|
.It Ar a
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|
print macro arguments.
|
|
.It Ar c
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|
print macro expansion over several lines.
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|
.It Ar e
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|
print result of macro expansion.
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|
.It Ar f
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|
print filename location.
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|
.It Ar l
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|
print line number.
|
|
.It Ar q
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|
quote arguments and expansion with the current quotes.
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|
.It Ar t
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|
start with all macros traced.
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|
.It Ar x
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|
number macro expansions.
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|
.It Ar V
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|
turn on all options.
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|
.El
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|
.Pp
|
|
By default, trace is set to
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|
.Qq eq .
|
|
.It Fl E
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|
Set warnings to be fatal.
|
|
When a single
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|
.Fl E
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|
flag is specified, if warnings are issued, execution
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|
continues but
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|
.Nm
|
|
will exit with a non-zero exit status.
|
|
When multiple
|
|
.Fl E
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|
flags are specified, execution will halt upon issuing the
|
|
first warning and
|
|
.Nm
|
|
will exit with a non-zero exit status.
|
|
This behaviour matches GNU-m4 1.4.9 and later.
|
|
.It Fl g
|
|
Activate GNU-m4 compatibility mode.
|
|
In this mode, translit handles simple character
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|
ranges (e.g., a-z), regular expressions mimic emacs behavior,
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|
multiple m4wrap calls are handled as a stack,
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|
the number of diversions is unlimited,
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|
empty names for macro definitions are allowed,
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|
and eval understands
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|
.Sq 0rbase:value
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|
numbers.
|
|
.It Fl I Ar "dirname"
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|
Add directory
|
|
.Ar dirname
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|
to the include path.
|
|
.It Fl o Ar filename
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|
Send trace output to
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|
.Ar filename .
|
|
.It Fl P
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|
Prefix all built-in macros with
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|
.Sq m4_ .
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|
For example, instead of writing
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|
.Ic define ,
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|
use
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|
.Ic m4_define .
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|
.It Fl s
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|
Output line synchronization directives, suitable for
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|
.Xr cpp 1 .
|
|
.It Fl t Ar macro
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|
Turn tracing on for
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|
.Ar macro .
|
|
.It Fl "U" Ns Ar "name"
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|
Undefine the symbol
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|
.Ar name .
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|
.El
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|
.Sh SYNTAX
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|
.Nm
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|
provides the following built-in macros.
|
|
They may be redefined, losing their original meaning.
|
|
Return values are null unless otherwise stated.
|
|
.Bl -tag -width changequote
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|
.It Fn builtin name
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|
Calls a built-in by its
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|
.Fa name ,
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|
overriding possible redefinitions.
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|
.It Fn changecom startcomment endcomment
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|
Changes the start comment and end comment sequences.
|
|
Comment sequences may be up to five characters long.
|
|
The default values are the hash sign
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|
and the newline character.
|
|
.Bd -literal -offset indent
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|
# This is a comment
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|
.Ed
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|
.Pp
|
|
With no arguments, comments are turned off.
|
|
With one single argument, the end comment sequence is set
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|
to the newline character.
|
|
.It Fn changequote beginquote endquote
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|
Defines the open quote and close quote sequences.
|
|
Quote sequences may be up to five characters long.
|
|
The default values are the backquote character and the quote
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|
character.
|
|
.Bd -literal -offset indent
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|
`Here is a quoted string'
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|
.Ed
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|
.Pp
|
|
With no arguments, the default quotes are restored.
|
|
With one single argument, the close quote sequence is set
|
|
to the newline character.
|
|
.It Fn decr arg
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|
Decrements the argument
|
|
.Fa arg
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|
by 1.
|
|
The argument
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|
.Fa arg
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|
must be a valid numeric string.
|
|
.It Fn define name value
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|
Define a new macro named by the first argument
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|
.Fa name
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|
to have the
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|
value of the second argument
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|
.Fa value .
|
|
Each occurrence of
|
|
.Sq $n
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|
(where
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|
.Ar n
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|
is 0 through 9) is replaced by the
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|
.Ar n Ns 'th
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|
argument.
|
|
.Sq $0
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|
is the name of the calling macro.
|
|
Undefined arguments are replaced by a null string.
|
|
.Sq $#
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|
is replaced by the number of arguments;
|
|
.Sq $*
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|
is replaced by all arguments comma separated;
|
|
.Sq $@
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|
is the same as
|
|
.Sq $*
|
|
but all arguments are quoted against further expansion.
|
|
.It Fn defn name ...
|
|
Returns the quoted definition for each argument.
|
|
This can be used to rename
|
|
macro definitions (even for built-in macros).
|
|
.It Fn divert num
|
|
There are 10 output queues (numbered 0-9).
|
|
At the end of processing
|
|
.Nm
|
|
concatenates all the queues in numerical order to produce the
|
|
final output.
|
|
Initially the output queue is 0.
|
|
The divert
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|
macro allows you to select a new output queue (an invalid argument
|
|
passed to divert causes output to be discarded).
|
|
.It Ic divnum
|
|
Returns the current output queue number.
|
|
.It Ic dnl
|
|
Discard input characters up to and including the next newline.
|
|
.It Fn dumpdef name ...
|
|
Prints the names and definitions for the named items, or for everything
|
|
if no arguments are passed.
|
|
.It Fn errprint msg
|
|
Prints the first argument on the standard error output stream.
|
|
.It Fn esyscmd cmd
|
|
Passes its first argument to a shell and returns the shell's standard output.
|
|
Note that the shell shares its standard input and standard error with
|
|
.Nm .
|
|
.It Fn eval expr[,radix[,minimum]]
|
|
Computes the first argument as an arithmetic expression using 32-bit
|
|
arithmetic.
|
|
Operators are the standard C ternary, arithmetic, logical,
|
|
shift, relational, bitwise, and parentheses operators.
|
|
You can specify
|
|
octal, decimal, and hexadecimal numbers as in C.
|
|
The optional second argument
|
|
.Fa radix
|
|
specifies the radix for the result and the optional third argument
|
|
.Fa minimum
|
|
specifies the minimum number of digits in the result.
|
|
.It Fn expr expr
|
|
This is an alias for
|
|
.Ic eval .
|
|
.It Fn format formatstring arg1 ...
|
|
Returns
|
|
.Fa formatstring
|
|
with escape sequences substituted with
|
|
.Fa arg1
|
|
and following arguments, in a way similar to
|
|
.Xr printf 3 .
|
|
This built-in is only available in GNU-m4 compatibility mode, and the only
|
|
parameters implemented are there for autoconf compatibility:
|
|
left-padding flag, an optional field width, a maximum field width,
|
|
*-specified field widths, and the %s and %c data type.
|
|
.It Fn ifdef name yes no
|
|
If the macro named by the first argument is defined then return the second
|
|
argument, otherwise the third.
|
|
If there is no third argument, the value is
|
|
.Dv NULL .
|
|
The word
|
|
.Qq unix
|
|
is predefined.
|
|
.It Fn ifelse a b yes ...
|
|
If the first argument
|
|
.Fa a
|
|
matches the second argument
|
|
.Fa b
|
|
then
|
|
.Fn ifelse
|
|
returns
|
|
the third argument
|
|
.Fa yes .
|
|
If the match fails the three arguments are
|
|
discarded and the next three arguments are used until there is
|
|
zero or one arguments left, either this last argument or
|
|
.Dv NULL
|
|
is returned if no other matches were found.
|
|
.It Fn include name
|
|
Returns the contents of the file specified in the first argument.
|
|
If the file is not found as is, look through the include path:
|
|
first the directories specified with
|
|
.Fl I
|
|
on the command line, then the environment variable
|
|
.Ev M4PATH ,
|
|
as a colon-separated list of directories.
|
|
Include aborts with an error message if the file cannot be included.
|
|
.It Fn incr arg
|
|
Increments the argument by 1.
|
|
The argument must be a valid numeric string.
|
|
.It Fn index string substring
|
|
Returns the index of the second argument in the first argument (e.g.,
|
|
.Ic index(the quick brown fox jumped, fox)
|
|
returns 16).
|
|
If the second
|
|
argument is not found index returns \-1.
|
|
.It Fn indir macro arg1 ...
|
|
Indirectly calls the macro whose name is passed as the first argument,
|
|
with the remaining arguments passed as first, ... arguments.
|
|
.It Fn len arg
|
|
Returns the number of characters in the first argument.
|
|
Extra arguments
|
|
are ignored.
|
|
.It Fn m4exit code
|
|
Immediately exits with the return value specified by the first argument,
|
|
0 if none.
|
|
.It Fn m4wrap todo
|
|
Allows you to define what happens at the final
|
|
.Dv EOF ,
|
|
usually for cleanup purposes (e.g.,
|
|
.Ic m4wrap("cleanup(tempfile)")
|
|
causes the macro cleanup to be
|
|
invoked after all other processing is done).
|
|
.Pp
|
|
Multiple calls to
|
|
.Fn m4wrap
|
|
get inserted in sequence at the final
|
|
.Dv EOF .
|
|
.It Fn maketemp template
|
|
Like
|
|
.Ic mkstemp .
|
|
.It Fn mkstemp template
|
|
Invokes
|
|
.Xr mkstemp 3
|
|
on the first argument, and returns the modified string.
|
|
This can be used to create unique
|
|
temporary file names.
|
|
.It Fn paste file
|
|
Includes the contents of the file specified by the first argument without
|
|
any macro processing.
|
|
Aborts with an error message if the file cannot be
|
|
included.
|
|
.It Fn patsubst string regexp replacement
|
|
Substitutes a regular expression in a string with a replacement string.
|
|
Usual substitution patterns apply: an ampersand
|
|
.Pq Sq \&&
|
|
is replaced by the string matching the regular expression.
|
|
The string
|
|
.Sq \e# ,
|
|
where
|
|
.Sq #
|
|
is a digit, is replaced by the corresponding back-reference.
|
|
.It Fn popdef arg ...
|
|
Restores the
|
|
.Ic pushdef Ns ed
|
|
definition for each argument.
|
|
.It Fn pushdef macro def
|
|
Takes the same arguments as
|
|
.Ic define ,
|
|
but it saves the definition on a
|
|
stack for later retrieval by
|
|
.Fn popdef .
|
|
.It Fn regexp string regexp replacement
|
|
Finds a regular expression in a string.
|
|
If no further arguments are given,
|
|
it returns the first match position or \-1 if no match.
|
|
If a third argument
|
|
is provided, it returns the replacement string, with sub-patterns replaced.
|
|
.It Fn shift arg1 ...
|
|
Returns all but the first argument, the remaining arguments are
|
|
quoted and pushed back with commas in between.
|
|
The quoting
|
|
nullifies the effect of the extra scan that will subsequently be
|
|
performed.
|
|
.It Fn sinclude file
|
|
Similar to
|
|
.Ic include ,
|
|
except it ignores any errors.
|
|
.It Fn spaste file
|
|
Similar to
|
|
.Fn paste ,
|
|
except it ignores any errors.
|
|
.It Fn substr string offset length
|
|
Returns a substring of the first argument starting at the offset specified
|
|
by the second argument and the length specified by the third argument.
|
|
If no third argument is present it returns the rest of the string.
|
|
.It Fn syscmd cmd
|
|
Passes the first argument to the shell.
|
|
Nothing is returned.
|
|
.It Ic sysval
|
|
Returns the return value from the last
|
|
.Ic syscmd .
|
|
.It Fn traceon arg ...
|
|
Enables tracing of macro expansions for the given arguments, or for all
|
|
macros if no argument is given.
|
|
.It Fn traceoff arg ...
|
|
Disables tracing of macro expansions for the given arguments, or for all
|
|
macros if no argument is given.
|
|
.It Fn translit string mapfrom mapto
|
|
Transliterate the characters in the first argument from the set
|
|
given by the second argument to the set given by the third.
|
|
You cannot use
|
|
.Xr tr 1
|
|
style abbreviations.
|
|
.It Fn undefine name1 ...
|
|
Removes the definition for the macros specified by its arguments.
|
|
.It Fn undivert arg ...
|
|
Flushes the named output queues (or all queues if no arguments).
|
|
.It Ic unix
|
|
A pre-defined macro for testing the OS platform.
|
|
.It Ic __line__
|
|
Returns the current file's line number.
|
|
.It Ic __file__
|
|
Returns the current file's name.
|
|
.El
|
|
.Sh EXIT STATUS
|
|
.Ex -std m4
|
|
.Pp
|
|
But note that the
|
|
.Ic m4exit
|
|
macro can modify the exit status, as can the
|
|
.Fl E
|
|
flag.
|
|
.Sh SEE ALSO
|
|
.Rs
|
|
.\" 4.4BSD PSD:17
|
|
.%A B. W. Kernighan
|
|
.%A D. M. Ritchie
|
|
.%I AT&T Bell Laboratories
|
|
.%T The M4 Macro Processor
|
|
.%R Computing Science Technical Report
|
|
.%N 59
|
|
.%D July 1977
|
|
.Re
|
|
.Sh STANDARDS
|
|
The
|
|
.Nm
|
|
utility is compliant with the
|
|
.St -p1003.1-2008
|
|
specification.
|
|
.Pp
|
|
The flags
|
|
.Op Fl dEgIPot
|
|
and the macros
|
|
.Ic builtin ,
|
|
.Ic esyscmd ,
|
|
.Ic expr ,
|
|
.Ic format ,
|
|
.Ic indir ,
|
|
.Ic paste ,
|
|
.Ic patsubst ,
|
|
.Ic regexp ,
|
|
.Ic spaste ,
|
|
.Ic unix ,
|
|
.Ic __line__ ,
|
|
and
|
|
.Ic __file__
|
|
are extensions to that specification.
|
|
.Pp
|
|
.Ic maketemp
|
|
is not supposed to be a synonym for
|
|
.Ic mkstemp ,
|
|
but instead to be an insecure temporary file name creation function.
|
|
It is marked by
|
|
.St -p1003.1-2008
|
|
as being obsolescent and should not be used if portability is a concern.
|
|
.Pp
|
|
The output format of
|
|
.Ic traceon
|
|
and
|
|
.Ic dumpdef
|
|
are not specified in any standard,
|
|
are likely to change and should not be relied upon.
|
|
The current format of tracing is closely modelled on
|
|
.Nm gnu-m4 ,
|
|
to allow
|
|
.Nm autoconf
|
|
to work.
|
|
.Pp
|
|
The built-ins
|
|
.Ic pushdef
|
|
and
|
|
.Ic popdef
|
|
handle macro definitions as a stack.
|
|
However,
|
|
.Ic define
|
|
interacts with the stack in an undefined way.
|
|
In this implementation,
|
|
.Ic define
|
|
replaces the top-most definition only.
|
|
Other implementations may erase all definitions on the stack instead.
|
|
.Pp
|
|
All built-ins do expand without arguments in many other
|
|
.Nm .
|
|
.Pp
|
|
Many other
|
|
.Nm
|
|
have dire size limitations with respect to buffer sizes.
|
|
.Sh AUTHORS
|
|
.An -nosplit
|
|
.An Ozan Yigit Aq Mt oz@sis.yorku.ca
|
|
and
|
|
.An Richard A. O'Keefe Aq Mt ok@goanna.cs.rmit.OZ.AU .
|
|
.Pp
|
|
GNU-m4 compatibility extensions by
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.An Marc Espie Aq Mt espie@cvs.openbsd.org .
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