PERL(1) Perl Programmers Reference Guide PERL(1)NAMEperl - Practical Extraction and Report Language
SYNOPSISperl [ -sTuU ] [ -hv ] [ -V[:configvar] ]
[ -cw ] [ -d[:debugger] ] [ -D[number/list] ]
[ -pna ] [ -Fpattern ] [ -l[octal] ] [ -0[octal] ]
[ -Idir ] [ -m[-]module ] [ -M[-]'module...' ]
[ -P ] [ -S ] [ -x[dir] ]
[ -i[extension] ] [ -e 'command' ] [ -- ] [ program_
file ] [ argument ]...
For ease of access, the Perl manual has been split up into
several sections:
perl Perl overview (this section)
perlfaq Perl frequently asked questions
perltoc Perl documentation table of contents
perlbook Perl book information
perlsyn Perl syntax
perldata Perl data structures
perlop Perl operators and precedence
perlsub Perl subroutines
perlfunc Perl builtin functions
perlreftut Perl references short introduction
perldsc Perl data structures intro
perlrequick Perl regular expressions quick start
perlpod Perl plain old documentation
perlstyle Perl style guide
perltrap Perl traps for the unwary
perlrun Perl execution and options
perldiag Perl diagnostic messages
perllexwarn Perl warnings and their control
perldebtut Perl debugging tutorial
perldebug Perl debugging
perlvar Perl predefined variables
perllol Perl data structures: arrays of arrays
perlopentut Perl open() tutorial
perlretut Perl regular expressions tutorial
perlre Perl regular expressions, the rest of the story
perlref Perl references, the rest of the story
perlform Perl formats
perlboot Perl OO tutorial for beginners
perltoot Perl OO tutorial, part 1
perltootc Perl OO tutorial, part 2
perlobj Perl objects
perlbot Perl OO tricks and examples
perltie Perl objects hidden behind simple variables
perlipc Perl interprocess communication
perlfork Perl fork() information
perlnumber Perl number semantics
perlthrtut Perl threads tutorial
perlport Perl portability guide
perllocale Perl locale support
perlunicode Perl unicode support
perlebcdic Considerations for running Perl on EBCDIC platforms
perlsec Perl security
perlmod Perl modules: how they work
perlmodlib Perl modules: how to write and use
perlmodinstall Perl modules: how to install from CPAN
perlnewmod Perl modules: preparing a new module for distribution
perlfaq1 General Questions About Perl
perlfaq2 Obtaining and Learning about Perl
perlfaq3 Programming Tools
perlfaq4 Data Manipulation
perlfaq5 Files and Formats
perlfaq6 Regexes
perlfaq7 Perl Language Issues
perlfaq8 System Interaction
perlfaq9 Networking
perlcompile Perl compiler suite intro
perlembed Perl ways to embed perl in your C or C++ application
perldebguts Perl debugging guts and tips
perlxstut Perl XS tutorial
perlxs Perl XS application programming interface
perlclib Internal replacements for standard C library functions
perlguts Perl internal functions for those doing extensions
perlcall Perl calling conventions from C
perlutil utilities packaged with the Perl distribution
perlfilter Perl source filters
perldbmfilter Perl DBM filters
perlapi Perl API listing (autogenerated)
perlintern Perl internal functions (autogenerated)
perlapio Perl internal IO abstraction interface
perltodo Perl things to do
perlhack Perl hackers guide
perlhist Perl history records
perldelta Perl changes since previous version
perl5005delta Perl changes in version 5.005
perl5004delta Perl changes in version 5.004
perlaix Perl notes for AIX
perlamiga Perl notes for Amiga
perlbs2000 Perl notes for POSIX-BC BS2000
perlcygwin Perl notes for Cygwin
perldos Perl notes for DOS
perlepoc Perl notes for EPOC
perlhpux Perl notes for HP-UX
perlmachten Perl notes for Power MachTen
perlmacos Perl notes for Mac OS (Classic)
perlmpeix Perl notes for MPE/iX
perlos2 Perl notes for OS/2
perlos390 Perl notes for OS/390
perlsolaris Perl notes for Solaris
perlvmesa Perl notes for VM/ESA
perlvms Perl notes for VMS
perlvos Perl notes for Stratus VOS
perlwin32 Perl notes for Windows
(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, the manpages listed above are installed in the
/usr/local/man/ directory.
Extensive additional documentation for Perl modules is
available. The default configuration for perl will place
this additional documentation in the
/usr/local/lib/perl5/man directory (or else in the 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
/usr/local/man/man1 and /usr/local/man/man3, you need only
to add that stem (/usr/local/man) to your man(1) configu
ration 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 perldoc script to view module information.
You might also look into getting a replacement man pro
gram.
If something strange has gone wrong with your program and
you're not sure where you should look for help, try the -w
switch first. It will often point out exactly where the
trouble is.
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 lan
guage 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, sed, awk, and sh, so people famil
iar with those languages should have little difficulty
with it. (Language historians will also note some ves
tiges of csh, Pascal, and even BASIC-PLUS.) Expression
syntax corresponds 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 (some
times called "associative arrays") grow as necessary to
prevent degraded performance. Perl can use sophisticated
pattern matching techniques to scan large amounts of data
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 pro
grams through a dataflow tracing mechanism that prevents
many stupid security holes.
If you have a problem that would ordinarily use sed or awk
or 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 transla
tors to turn your sed and awk scripts into Perl scripts.
But wait, there's more...
Begun in 1993 (see the perlhist manpage), Perl version 5
is nearly a complete rewrite that provides the following
additional benefits:
modularity and reusability using innumerable modules
Described in the perlmod manpage, the perlmodlib man
page, and the perlmodinstall manpage.
embeddable and extensible
Described in the perlembed manpage, the perlxstut man
page, the perlxs manpage, the perlcall manpage, the
perlguts manpage, and the xsubpp manpage.
roll-your-own magic variables (including multiple
simultaneous DBM implementations)
Described in the perltie manpage and the AnyDBM_File
manpage.
subroutines can now be overridden, autoloaded, and
prototyped
Described in the perlsub manpage.
arbitrarily nested data structures and anonymous func
tions
Described in the perlreftut manpage, the perlref man
page, the perldsc manpage, and the perllol manpage.
object-oriented programming
Described in the perlobj manpage, the perltoot man
page, and the perlbot manpage.
compilability into C code or Perl bytecode
Described in the B manpage and the B::Bytecode man
page.
support for light-weight processes (threads)
Described in the perlthrtut manpage and the Thread
manpage.
support for internationalization, localization, and
Unicode
Described in the perllocale manpage and the utf8 man
page.
lexical scoping
Described in the perlsub manpage.
regular expression enhancements
Described in the perlre manpage, with additional
examples in the perlop manpage.
enhanced debugger and interactive Perl environment,
with integrated editor support
Described in the perldebug manpage.
POSIX 1003.1 compliant library
Described in the POSIX manpage.
Okay, that's definitely enough hype.
AVAILABILITY
Perl is available for most operating systems, including
virtually all Unix-like platforms. See the Supported
Platforms entry in the perlport manpage for a listing.
ENVIRONMENT
See the perlrun manpage.
AUTHOR
Larry Wall <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 perl-thanks@perl.org .
FILES
"@INC" locations of perl libraries
SEE ALSO
a2p awk to perl translator
s2p sed to perl translator
http://www.perl.com/ the Perl Home Page
http://www.perl.com/CPAN the Comprehensive Perl Archive
DIAGNOSTICS
The "use warnings" pragma (and the -w switch) produces
some lovely diagnostics.
See the perldiag manpage for explanations of all Perl's
diagnostics. The "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 a script passed to Perl via
-e switches, each -e is counted as one line.)
Setuid scripts have additional constraints that can pro
duce error messages such as "Insecure dependency". See
the perlsec manpage.
Did we mention that you should definitely consider using
the -w switch?
BUGS
The -w switch is not mandatory.
Perl is at the mercy of your machine's definitions of var
ious operations such as type casting, atof(), and float
ing-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 pro
gram in the perl source tree, or by "perl -V") to perl
bug@perl.org . 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.
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.
2001-04-07 perl v5.6.1 PERL(1)
