397 lines
15 KiB
Plaintext
397 lines
15 KiB
Plaintext
=head1 NAME
|
|
|
|
perl - Practical Extraction and Report Language
|
|
|
|
=head1 SYNOPSIS
|
|
|
|
B<perl> S<[ B<-sTuU> ]>
|
|
S<[ B<-hv> ] [ B<-V>[:I<configvar>] ]>
|
|
S<[ B<-cw> ] [ B<-d>[:I<debugger>] ] [ B<-D>[I<number/list>] ]>
|
|
S<[ B<-pna> ] [ B<-F>I<pattern> ] [ B<-l>[I<octal>] ] [ B<-0>[I<octal>] ]>
|
|
S<[ B<-I>I<dir> ] [ B<-m>[B<->]I<module> ] [ B<-M>[B<->]I<'module...'> ]>
|
|
S<[ B<-P> ]>
|
|
S<[ B<-S> ]>
|
|
S<[ B<-x>[I<dir>] ]>
|
|
S<[ B<-i>[I<extension>] ]>
|
|
S<[ B<-e> I<'command'> ] [ B<--> ] [ I<programfile> ] [ I<argument> ]...>
|
|
|
|
For ease of access, the Perl manual has been split up into a number
|
|
of sections:
|
|
|
|
perl Perl overview (this section)
|
|
perldelta Perl changes since previous version
|
|
perl5004delta Perl changes in version 5.004
|
|
perlfaq Perl frequently asked questions
|
|
perltoc Perl documentation table of contents
|
|
|
|
perldata Perl data structures
|
|
perlsyn Perl syntax
|
|
perlop Perl operators and precedence
|
|
perlre Perl regular expressions
|
|
perlrun Perl execution and options
|
|
perlfunc Perl builtin functions
|
|
perlopentut Perl open() tutorial
|
|
perlvar Perl predefined variables
|
|
perlsub Perl subroutines
|
|
perlmod Perl modules: how they work
|
|
perlmodlib Perl modules: how to write and use
|
|
perlmodinstall Perl modules: how to install from CPAN
|
|
perlform Perl formats
|
|
perllocale Perl locale support
|
|
|
|
perlref Perl references
|
|
perlreftut Perl references short introduction
|
|
perldsc Perl data structures intro
|
|
perllol Perl data structures: lists of lists
|
|
perltoot Perl OO tutorial
|
|
perlobj Perl objects
|
|
perltie Perl objects hidden behind simple variables
|
|
perlbot Perl OO tricks and examples
|
|
perlipc Perl interprocess communication
|
|
perlthrtut Perl threads tutorial
|
|
|
|
perldebug Perl debugging
|
|
perldiag Perl diagnostic messages
|
|
perlsec Perl security
|
|
perltrap Perl traps for the unwary
|
|
perlport Perl portability guide
|
|
perlstyle Perl style guide
|
|
|
|
perlpod Perl plain old documentation
|
|
perlbook Perl book information
|
|
|
|
perlembed Perl ways to embed perl in your C or C++ application
|
|
perlapio Perl internal IO abstraction interface
|
|
perlxs Perl XS application programming interface
|
|
perlxstut Perl XS tutorial
|
|
perlguts Perl internal functions for those doing extensions
|
|
perlcall Perl calling conventions from C
|
|
|
|
perlhist Perl history records
|
|
|
|
(If you're intending to read these straight through for the first time,
|
|
the suggested order will tend to reduce the number of forward references.)
|
|
|
|
By default, all of the above manpages are installed in the
|
|
F</usr/local/man/> directory.
|
|
|
|
Extensive additional documentation for Perl modules is available. The
|
|
default configuration for perl will place this additional documentation
|
|
in the F</usr/local/lib/perl5/man> directory (or else in the F<man>
|
|
subdirectory of the Perl library directory). Some of this additional
|
|
documentation is distributed standard with Perl, but you'll also find
|
|
documentation for third-party modules there.
|
|
|
|
You should be able to view Perl's documentation with your man(1)
|
|
program by including the proper directories in the appropriate start-up
|
|
files, or in the MANPATH environment variable. To find out where the
|
|
configuration has installed the manpages, type:
|
|
|
|
perl -V:man.dir
|
|
|
|
If the directories have a common stem, such as F</usr/local/man/man1>
|
|
and F</usr/local/man/man3>, you need only to add that stem
|
|
(F</usr/local/man>) to your man(1) configuration files or your MANPATH
|
|
environment variable. If they do not share a stem, you'll have to add
|
|
both stems.
|
|
|
|
If that doesn't work for some reason, you can still use the
|
|
supplied F<perldoc> script to view module information. You might
|
|
also look into getting a replacement man program.
|
|
|
|
If something strange has gone wrong with your program and you're not
|
|
sure where you should look for help, try the B<-w> switch first. It
|
|
will often point out exactly where the trouble is.
|
|
|
|
=head1 DESCRIPTION
|
|
|
|
Perl is a language optimized for scanning arbitrary
|
|
text files, extracting information from those text files, and printing
|
|
reports based on that information. It's also a good language for many
|
|
system management tasks. The language is intended to be practical
|
|
(easy to use, efficient, complete) rather than beautiful (tiny,
|
|
elegant, minimal).
|
|
|
|
Perl combines (in the author's opinion, anyway) some of the best
|
|
features of C, B<sed>, B<awk>, and B<sh>, so people familiar with
|
|
those languages should have little difficulty with it. (Language
|
|
historians will also note some vestiges of B<csh>, Pascal, and even
|
|
BASIC-PLUS.) Expression syntax corresponds quite closely to C
|
|
expression syntax. Unlike most Unix utilities, Perl does not
|
|
arbitrarily limit the size of your data--if you've got the memory,
|
|
Perl can slurp in your whole file as a single string. Recursion is of
|
|
unlimited depth. And the tables used by hashes (sometimes called
|
|
"associative arrays") grow as necessary to prevent degraded
|
|
performance. Perl can use sophisticated pattern matching techniques to
|
|
scan large amounts of data very quickly. Although optimized for
|
|
scanning text, Perl can also deal with binary data, and can make dbm
|
|
files look like hashes. Setuid Perl scripts are safer than C programs
|
|
through a dataflow tracing mechanism which prevents many stupid
|
|
security holes.
|
|
|
|
If you have a problem that would ordinarily use B<sed> or B<awk> or
|
|
B<sh>, but it exceeds their capabilities or must run a little faster,
|
|
and you don't want to write the silly thing in C, then Perl may be for
|
|
you. There are also translators to turn your B<sed> and B<awk>
|
|
scripts into Perl scripts.
|
|
|
|
But wait, there's more...
|
|
|
|
Perl version 5 is nearly a complete rewrite, and provides
|
|
the following additional benefits:
|
|
|
|
=over 5
|
|
|
|
=item * Many usability enhancements
|
|
|
|
It is now possible to write much more readable Perl code (even within
|
|
regular expressions). Formerly cryptic variable names can be replaced
|
|
by mnemonic identifiers. Error messages are more informative, and the
|
|
optional warnings will catch many of the mistakes a novice might make.
|
|
This cannot be stressed enough. Whenever you get mysterious behavior,
|
|
try the B<-w> switch!!! Whenever you don't get mysterious behavior,
|
|
try using B<-w> anyway.
|
|
|
|
=item * Simplified grammar
|
|
|
|
The new yacc grammar is one half the size of the old one. Many of the
|
|
arbitrary grammar rules have been regularized. The number of reserved
|
|
words has been cut by 2/3. Despite this, nearly all old Perl scripts
|
|
will continue to work unchanged.
|
|
|
|
=item * Lexical scoping
|
|
|
|
Perl variables may now be declared within a lexical scope, like "auto"
|
|
variables in C. Not only is this more efficient, but it contributes
|
|
to better privacy for "programming in the large". Anonymous
|
|
subroutines exhibit deep binding of lexical variables (closures).
|
|
|
|
=item * Arbitrarily nested data structures
|
|
|
|
Any scalar value, including any array element, may now contain a
|
|
reference to any other variable or subroutine. You can easily create
|
|
anonymous variables and subroutines. Perl manages your reference
|
|
counts for you.
|
|
|
|
=item * Modularity and reusability
|
|
|
|
The Perl library is now defined in terms of modules which can be easily
|
|
shared among various packages. A package may choose to import all or a
|
|
portion of a module's published interface. Pragmas (that is, compiler
|
|
directives) are defined and used by the same mechanism.
|
|
|
|
=item * Object-oriented programming
|
|
|
|
A package can function as a class. Dynamic multiple inheritance and
|
|
virtual methods are supported in a straightforward manner and with very
|
|
little new syntax. Filehandles may now be treated as objects.
|
|
|
|
=item * Embeddable and Extensible
|
|
|
|
Perl may now be embedded easily in your C or C++ application, and can
|
|
either call or be called by your routines through a documented
|
|
interface. The XS preprocessor is provided to make it easy to glue
|
|
your C or C++ routines into Perl. Dynamic loading of modules is
|
|
supported, and Perl itself can be made into a dynamic library.
|
|
|
|
=item * POSIX compliant
|
|
|
|
A major new module is the POSIX module, which provides access to all
|
|
available POSIX routines and definitions, via object classes where
|
|
appropriate.
|
|
|
|
=item * Package constructors and destructors
|
|
|
|
The new BEGIN and END blocks provide means to capture control as
|
|
a package is being compiled, and after the program exits. As a
|
|
degenerate case they work just like awk's BEGIN and END when you
|
|
use the B<-p> or B<-n> switches.
|
|
|
|
=item * Multiple simultaneous DBM implementations
|
|
|
|
A Perl program may now access DBM, NDBM, SDBM, GDBM, and Berkeley DB
|
|
files from the same script simultaneously. In fact, the old dbmopen
|
|
interface has been generalized to allow any variable to be tied
|
|
to an object class which defines its access methods.
|
|
|
|
=item * Subroutine definitions may now be autoloaded
|
|
|
|
In fact, the AUTOLOAD mechanism also allows you to define any arbitrary
|
|
semantics for undefined subroutine calls. It's not for just autoloading.
|
|
|
|
=item * Regular expression enhancements
|
|
|
|
You can now specify nongreedy quantifiers. You can now do grouping
|
|
without creating a backreference. You can now write regular expressions
|
|
with embedded whitespace and comments for readability. A consistent
|
|
extensibility mechanism has been added that is upwardly compatible with
|
|
all old regular expressions.
|
|
|
|
=item * Innumerable Unbundled Modules
|
|
|
|
The Comprehensive Perl Archive Network described in L<perlmodlib>
|
|
contains hundreds of plug-and-play modules full of reusable code.
|
|
See F<http://www.perl.com/CPAN> for a site near you.
|
|
|
|
=item * Compilability
|
|
|
|
While not yet in full production mode, a working perl-to-C compiler
|
|
does exist. It can generate portable byte code, simple C, or
|
|
optimized C code.
|
|
|
|
=back
|
|
|
|
Okay, that's I<definitely> enough hype.
|
|
|
|
=head1 AVAILABILITY
|
|
|
|
Perl is available for the vast majority of operating system platforms,
|
|
including most Unix-like platforms. The following situation is as of
|
|
February 1999 and Perl 5.005_03.
|
|
|
|
The following platforms are able to build Perl from the standard
|
|
source code distribution available at
|
|
F<http://www.perl.com/CPAN/src/index.html>
|
|
|
|
AIX Linux SCO ODT/OSR
|
|
A/UX MachTen Solaris
|
|
BeOS MPE/iX SunOS
|
|
BSD/OS NetBSD SVR4
|
|
DG/UX NextSTEP Tru64 UNIX 3)
|
|
DomainOS OpenBSD Ultrix
|
|
DOS DJGPP 1) OpenSTEP UNICOS
|
|
DYNIX/ptx OS/2 VMS
|
|
FreeBSD OS390 2) VOS
|
|
HP-UX PowerMAX Windows 3.1 1)
|
|
Hurd QNX Windows 95 1) 4)
|
|
IRIX Windows 98 1) 4)
|
|
Windows NT 1) 4)
|
|
|
|
1) in DOS mode either the DOS or OS/2 ports can be used
|
|
2) formerly known as MVS
|
|
3) formerly known as Digital UNIX and before that DEC OSF/1
|
|
4) compilers: Borland, Cygwin32, Mingw32 EGCS/GCC, VC++
|
|
|
|
The following platforms have been known to build Perl from the source
|
|
but for the Perl release 5.005_03 we haven't been able to verify them,
|
|
either because the hardware/software platforms are rather rare or
|
|
because we don't have an active champion on these platforms, or both.
|
|
|
|
3b1 FPS Plan 9
|
|
AmigaOS GENIX PowerUX
|
|
ConvexOS Greenhills RISC/os
|
|
CX/UX ISC Stellar
|
|
DC/OSx MachTen 68k SVR2
|
|
DDE SMES MiNT TI1500
|
|
DOS EMX MPC TitanOS
|
|
Dynix NEWS-OS UNICOS/mk
|
|
EP/IX Opus Unisys Dynix
|
|
ESIX Unixware
|
|
|
|
The following platforms are planned to be supported in the standard
|
|
source code distribution of the Perl release 5.006 but are not
|
|
supported in the Perl release 5.005_03:
|
|
|
|
BS2000
|
|
Netware
|
|
Rhapsody
|
|
VM/ESA
|
|
|
|
The following platforms have their own source code distributions and
|
|
binaries available via F<http://www.perl.com/CPAN/ports/index.html>.
|
|
|
|
Perl release
|
|
|
|
AS/400 5.003
|
|
MacOS 5.004
|
|
Netware 5.003_07
|
|
Tandem Guardian 5.004
|
|
|
|
The following platforms have only binaries available via
|
|
F<http://www.perl.com/CPAN/ports/index.html>.
|
|
|
|
Perl release
|
|
|
|
Acorn RISCOS 5.005_02
|
|
AOS 5.002
|
|
LynxOS 5.004_02
|
|
|
|
=head1 ENVIRONMENT
|
|
|
|
See L<perlrun>.
|
|
|
|
=head1 AUTHOR
|
|
|
|
Larry Wall <F<larry@wall.org>>, with the help of oodles of other folks.
|
|
|
|
If your Perl success stories and testimonials may be of help to others
|
|
who wish to advocate the use of Perl in their applications,
|
|
or if you wish to simply express your gratitude to Larry and the
|
|
Perl developers, please write to <F<perl-thanks@perl.org>>.
|
|
|
|
=head1 FILES
|
|
|
|
"@INC" locations of perl libraries
|
|
|
|
=head1 SEE ALSO
|
|
|
|
a2p awk to perl translator
|
|
|
|
s2p sed to perl translator
|
|
|
|
=head1 DIAGNOSTICS
|
|
|
|
The B<-w> switch produces some lovely diagnostics.
|
|
|
|
See L<perldiag> for explanations of all Perl's diagnostics. The C<use
|
|
diagnostics> pragma automatically turns Perl's normally terse warnings
|
|
and errors into these longer forms.
|
|
|
|
Compilation errors will tell you the line number of the error, with an
|
|
indication of the next token or token type that was to be examined.
|
|
(In the case of a script passed to Perl via B<-e> switches, each
|
|
B<-e> is counted as one line.)
|
|
|
|
Setuid scripts have additional constraints that can produce error
|
|
messages such as "Insecure dependency". See L<perlsec>.
|
|
|
|
Did we mention that you should definitely consider using the B<-w>
|
|
switch?
|
|
|
|
=head1 BUGS
|
|
|
|
The B<-w> switch is not mandatory.
|
|
|
|
Perl is at the mercy of your machine's definitions of various
|
|
operations such as type casting, atof(), and floating-point
|
|
output with sprintf().
|
|
|
|
If your stdio requires a seek or eof between reads and writes on a
|
|
particular stream, so does Perl. (This doesn't apply to sysread()
|
|
and syswrite().)
|
|
|
|
While none of the built-in data types have any arbitrary size limits
|
|
(apart from memory size), there are still a few arbitrary limits: a
|
|
given variable name may not be longer than 251 characters. Line numbers
|
|
displayed by diagnostics are internally stored as short integers,
|
|
so they are limited to a maximum of 65535 (higher numbers usually being
|
|
affected by wraparound).
|
|
|
|
You may mail your bug reports (be sure to include full configuration
|
|
information as output by the myconfig program in the perl source tree,
|
|
or by C<perl -V>) to <F<perlbug@perl.com>>.
|
|
If you've succeeded in compiling perl, the perlbug script in the utils/
|
|
subdirectory can be used to help mail in a bug report.
|
|
|
|
Perl actually stands for Pathologically Eclectic Rubbish Lister, but
|
|
don't tell anyone I said that.
|
|
|
|
=head1 NOTES
|
|
|
|
The Perl motto is "There's more than one way to do it." Divining
|
|
how many more is left as an exercise to the reader.
|
|
|
|
The three principal virtues of a programmer are Laziness,
|
|
Impatience, and Hubris. See the Camel Book for why.
|
|
|