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 perlfaq Perl Freqently Asked Questions list
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 perlvar Perl predefined variables perlsub Perl subroutines perlmod Perl modules perlform Perl formats perllocale Perl locale support
perlref Perl references 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
perldebug Perl debugging perldiag Perl diagnostic messages perlsec Perl security perltrap Perl traps for the unwary perlstyle Perl style guide
perlpod Perl plain old documentation perlbook Perl book information
perlembed Perl how to embed perl in your C or C++ app 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
(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.)
Additional documentation for Perl modules is available in the
/usr/local/man/ directory. Some of this is distributed standard with Perl, but you'll also
find third-party modules there. You should be able to view this with your
man program by including the proper directories in the
appropriate start-up files. To find out where these are, type:
If the directories were /usr/local/man/man1 and /usr/local/man/man3, you would need to add only /usr/local/man to your MANPATH. If they are different, 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 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 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 (previously called ``associative arrays'') grow as necessary to prevent degraded performance. Perl uses 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 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...
Perl version 5 is nearly a complete rewrite, and provides the following additional benefits:
"/tmp/perl-e$$" temporary file for -e commands "@INC" locations of perl libraries
a2p awk to perl translator
s2p sed to perl translator
See the perldiag manpage for explanations of all Perl's diagnostics.
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 -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?
Perl is at the mercy of your machine's definitions of various operations
such as type casting,
latter can even trigger a core dump when passed ludicrous input values.
If your stdio requires a seek or eof between reads and writes on a
particular stream, so does Perl. (This doesn't apply to
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 255 characters, and no component of your PATH may be longer than 255 if you use -S. A regular expression may not compile to more than 32767 bytes internally.
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
perl -V) to <email@example.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.
The three principal virtues of a programmer are Laziness, Impatience, and Hubris. See the Camel Book for why.