perl - Practical Extraction and Report Language
NAME
SYNOPSIS
DESCRIPTION
AVAILABILITY
ENVIRONMENT
AUTHOR
FILES
SEE
ALSO
DIAGNOSTICS
BUGS
NOTES
NAME
perl - Practical Extraction and Report Language
SYNOPSIS
perl [ -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' ]
[ -- ] [ programfile ] [ argument ]...
For ease of access, the Perl manual has been split up into several
sections:
perl Perl overview (this section)
perldelta Perl changes since previous version
perl5005delta Perl changes in version 5.005
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
perlunicode Perl unicode support
perllocale Perl locale support
perlreftut Perl references short introduction
perlref Perl references, the rest of the story
perldsc Perl data structures intro
perllol Perl data structures: arrays of arrays
perlboot Perl OO tutorial for beginners
perltoot Perl OO tutorial, part 1
perltootc Perl OO tutorial, part 2
perlobj Perl objects
perltie Perl objects hidden behind simple variables
perlbot Perl OO tricks and examples
perlipc Perl interprocess communication
perlfork Perl fork() information
perlthrtut Perl threads tutorial
perllexwarn Perl warnings and their control
perlfilter Perl source filters
perldbmfilter Perl DBM filters
perlcompile Perl compiler suite intro
perldebug Perl debugging
perldiag Perl diagnostic messages
perlnumber Perl number semantics
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
perldebguts Perl debugging guts and tips
perlxs Perl XS application programming interface
perlxstut Perl XS tutorial
perlguts Perl internal functions for those doing extensions
perlcall Perl calling conventions from C
perlapi Perl API listing (autogenerated)
perlintern Perl internal functions (autogenerated)
perltodo Perl things to do
perlhack Perl hackers guide
perlhist Perl history records
perlamiga Perl notes for Amiga
perlcygwin Perl notes for Cygwin
perldos Perl notes for DOS
perlhpux Perl notes for HP-UX
perlmachten Perl notes for Power MachTen
perlos2 Perl notes for OS/2
perlos390 Perl notes for OS/390
perlvms Perl notes for VMS
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) 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 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 -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 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, sed, awk, and sh, so people familiar with
those languages should have little difficulty with it. (Language
historians will also note some vestiges 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 (sometimes 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 programs
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 translators 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 manpage, and the perlmodinstall manpage.
embeddable and extensible
Described in the perlembed manpage, the perlxstut manpage, the perlxs manpage, the perlcall manpage,
the perlguts manpage, and xsubpp.
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 functions
Described in the perlreftut manpage, the perlref manpage, the perldsc manpage, and the perllol manpage.
object-oriented programming
Described in the perlobj manpage, the perltoot manpage, and the perlbot manpage.
compilability into
C code or Perl bytecode
Described in the
B manpage and the B::Bytecode manpage.
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 manpage.
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 Supported Platforms 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 produce 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 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 perl -V) to 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.
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.
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