man pages for perl
SunOS 5.8 Last change: 15 Sep 1999
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 ] ...
DESCRIPTION
The Perl manual pages are provided with the programming
modules. To view the manual pages for the Perl modules with
the man command, add /usr/perl5/man to the MANPATH environ-
ment variable. See man(1) for more information. Running
catman(1M) on the Perl manual pages is not supported.
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
/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) configura-
tion 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
quite closely to C expression syntax. Unlike most Unix util-
ities, 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 sed or awk
or sh, but it exceeds their capabilities or must run a lit-
tle 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:
o 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 mys-
terious behavior, try the -w switch!!! Whenever
you don't get mysterious behavior, try using -w
anyway.
o 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.
o Lexical scoping
Perl variables may now be declared within a lexi-
cal 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).
o 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.
o 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. Prag-
mas (that is, compiler directives) are defined
and used by the same mechanism.
o Object-oriented programming
A package can function as a class. Dynamic multi-
ple inheritance and virtual methods are supported
in a straightforward manner and with very little
new syntax. Filehandles may now be treated as
objects.
o 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.
o 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.
o 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 -p or -n switches.
o 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 inter-
face has been generalized to allow any variable
to be tied to an object class which defines its
access methods.
o 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.
o Regular expression enhancements
You can now specify nongreedy quantifiers. You
can now do grouping without creating a backrefer-
ence. 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.
o Innumerable Unbundled Modules
The Comprehensive Perl Archive Network described
in the perlmodlib manpage contains hundreds of
plug-and-play modules full of reusable code. See
http://www.perl.com/CPAN for a site near you.
o 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.
Okay, that's definitely enough hype.
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
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
formerly known as Digital UNIX and before that DEC OSF/1
DomainOS OpenBSD Ultrix
DOS DJGPP OpenSTEP UNICOS
in DOS mode either the DOS or OS/2 ports can be used
DYNIX/ptx OS/2 VMS
FreeBSD OS390
formerly known as MVS VOS
HP-UX PowerMAX Windows 3.1
Hurd QNX Windows 95
compilers; Borland, Cygwin32, Mingw32 EGCS/GCC, VC++
IRIX Windows 98
Windows NT
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.
3bl FPS Plan 9
AmigaOS GENIX PowerUX
ConvexOS Greenhills RISC/os
CX/UX ISC Stellar
DC/OSx MachTen 68k SVR2
DDE SMES MiNT TIl500
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 distribu-
tions and binaries available via
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
http://www.perl.com/CPAN/ports/index.html:
Perl release
Acorn RISCOS 5.005_02
AOS 5.002
LynxOS 5.004_02
ENVIRONMENT
See the perlrun manpage.
AUTHOR
Larry Wall , 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 grati-
tude to Larry and the Perl developers, please write to
.
FILES
"@INC"
locations of perl libraries
ATTRIBUTES
See attributes(5) for descriptions of the following attri-
butes:
____________________________________________________________
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
|_____________________________|_____________________________|
| Availability | SUNWpl5u |
|_____________________________|_____________________________|
| | SUNWpl5p |
|_____________________________|_____________________________|
| | SUNWpl5m |
|_____________________________|_____________________________|
SEE ALSO
a2p awk to perl translator
s2p sed to perl translator
DIAGNOSTICS
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 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 perl-
sec manpage.
Did we mention that you should definitely consider using the
-w switch?
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.
BUGS
The -w switch is not mandatory.
Perl is at the mercy of your machine's definitions of vari-
ous 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 con-
figuration information as output by the myconfig program in
the perl source tree, or by perl -V) to .
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.