perl - Practical Extraction and Report Language |
perl - Practical Extraction and Report Language
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) 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)
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.
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:
Described in the perlmod manpage, the perlmodlib manpage, and the perlmodinstall manpage.
Described in the perlembed manpage, the perlxstut manpage, the perlxs manpage, the perlcall manpage, the perlguts manpage, and xsubpp.
Described in the perltie manpage and the AnyDBM_File manpage.
Described in the perlsub manpage.
Described in the perlreftut manpage, the perlref manpage, the perldsc manpage, and the perllol manpage.
Described in the perlobj manpage, the perltoot manpage, and the perlbot manpage.
Described in the B manpage and the B::Bytecode manpage.
Described in the perlthrtut manpage and the Thread manpage.
Described in the perllocale manpage and the utf8 manpage.
Described in the perlsub manpage.
Described in the perlre manpage, with additional examples in the perlop manpage.
Described in the perldebug manpage.
Described in the POSIX manpage.
Okay, that's definitely enough hype.
Perl is available for most operating systems, including virtually all Unix-like platforms. See Supported Platforms in the perlport manpage for a listing.
See the perlrun manpage.
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 .
"@INC" locations of perl libraries
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
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?
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.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.
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.
perl - Practical Extraction and Report Language |