Beefy Boxes and Bandwidth Generously Provided by pair Networks
Perl Monk, Perl Meditation


by gods (Initiate)
on Aug 25, 1999 at 07:36 UTC ( [id://427]=perlman: print w/replies, xml ) Need Help??


Current Perl documentation can be found at

Here is our local, out-dated (pre-5.6) version:


perltoc - perl documentation table of contents


This page provides a brief table of contents for the rest of the Perl documentation set. It is meant to be scanned quickly or grepped through to locate the proper section you're looking for.


perl - Practical Extraction and Report Language


Many usability enhancements, Simplified grammar, Lexical scoping, Arbitrarily nested data structures, Modularity and reusability, Object-oriented programming, Embeddable and Extensible, POSIX compliant, Package constructors and destructors, Multiple simultaneous DBM implementations, Subroutine definitions may now be autoloaded, Regular expression enhancements, Innumerable Unbundled Modules, Compilability


perlfaq - frequently asked questions about Perl ($Date: 1998/07/20 23:12:17 $)


perlfaq: Structural overview of the FAQ, the perlfaq1 manpage: General Questions About Perl, the perlfaq2 manpage: Obtaining and Learning about Perl, the perlfaq3 manpage: Programming Tools, the perlfaq4 manpage: Data Manipulation, the perlfaq5 manpage: Files and Formats, the perlfaq6 manpage: Regexps, the perlfaq7 manpage: General Perl Language Issues, the perlfaq8 manpage: System Interaction, the perlfaq9 manpage: Networking
Where to get this document
How to contribute to this document
What will happen if you mail your Perl programming problems to the authors
Author and Copyright Information
Bundled Distributions

24/April/97, 23/April/97, 25/March/97, 18/March/97, 17/March/97 Version, Initial Release: 11/March/97

perlfaq1 - General Questions About Perl ($Revision: 1.14 $, $Date: 1998/06/14 22:15:25 $)

What is Perl?
Who supports Perl? Who develops it? Why is it free?
Which version of Perl should I use?
What are perl4 and perl5?
How stable is Perl?
Is Perl difficult to learn?
How does Perl compare with other languages like Java, Python, REXX, Scheme, or Tcl?
Can I do [task] in Perl?
When shouldn't I program in Perl?
What's the difference between "perl" and "Perl"?
Is it a Perl program or a Perl script?
What is a JAPH?
Where can I get a list of Larry Wall witticisms?
How can I convince my sysadmin/supervisor/employees to use version (5/5.004/Perl instead of some other language)?

perlfaq2 - Obtaining and Learning about Perl ($Revision: 1.24 $, $Date: 1998/07/20 23:40:28 $)

What machines support Perl? Where do I get it?
How can I get a binary version of Perl?
I don't have a C compiler on my system. How can I compile perl?
I copied the Perl binary from one machine to another, but scripts don't work.
I grabbed the sources and tried to compile but gdbm/dynamic loading/malloc/linking/... failed. How do I make it work?
What modules and extensions are available for Perl? What is CPAN? What does CPAN/src/... mean?
Is there an ISO or ANSI certified version of Perl?
Where can I get information on Perl?
What are the Perl newsgroups on USENET? Where do I post questions?
Where should I post source code?
Perl Books

References, Tutorials *Learning Perl [2nd edition] by Randal L. Schwartz and Tom Christiansen, Task-Oriented, Special Topics

Perl in Magazines
Perl on the Net: FTP and WWW Access
What mailing lists are there for perl?

MacPerl, Perl5-Porters, NTPerl, Perl-Packrats

Archives of comp.lang.perl.misc
Where can I buy a commercial version of Perl?
Where do I send bug reports?
What is The Perl Institute?
How do I learn about object-oriented Perl programming?

perlfaq3 - Programming Tools ($Revision: 1.28 $, $Date: 1998/07/16 22:08:49 $)

How do I do (anything)?
How can I use Perl interactively?
Is there a Perl shell?
How do I debug my Perl programs?
How do I profile my Perl programs?
How do I cross-reference my Perl programs?
Is there a pretty-printer (formatter) for Perl?
Is there a ctags for Perl?
Where can I get Perl macros for vi?
Where can I get perl-mode for emacs?
How can I use curses with Perl?
How can I use X or Tk with Perl?
How can I generate simple menus without using CGI or Tk?
What is undump?
How can I make my Perl program run faster?
How can I make my Perl program take less memory?
Is it unsafe to return a pointer to local data?
How can I free an array or hash so my program shrinks?
How can I make my CGI script more efficient?
How can I hide the source for my Perl program?
How can I compile my Perl program into byte code or C?
How can I get #!perl to work on [MS-DOS,NT,...]?
Can I write useful perl programs on the command line?
Why don't perl one-liners work on my DOS/Mac/VMS system?
Where can I learn about CGI or Web programming in Perl?
Where can I learn about object-oriented Perl programming?
Where can I learn about linking C with Perl? [h2xs, xsubpp]
I've read perlembed, perlguts, etc., but I can't embed perl in my C program, what am I doing wrong?
When I tried to run my script, I got this message. What does it mean?
What's MakeMaker?

perlfaq4 - Data Manipulation ($Revision: 1.25 $, $Date: 1998/07/16 22:49:55 $)

Data: Numbers
Why am I getting long decimals (eg, 19.9499999999999) instead of the numbers I should be getting (eg, 19.95)?
Why isn't my octal data interpreted correctly?
Does perl have a round function? What about ceil() and floor()? Trig functions?
How do I convert bits into ints?
How do I multiply matrices?
How do I perform an operation on a series of integers?
How can I output Roman numerals?
Why aren't my random numbers random?
Data: Dates
How do I find the week-of-the-year/day-of-the-year?
How can I compare two dates and find the difference?
How can I take a string and turn it into epoch seconds?
How can I find the Julian Day?
Does Perl have a year 2000 problem? Is Perl Y2K compliant?
Data: Strings
How do I validate input?
How do I unescape a string?
How do I remove consecutive pairs of characters?
How do I expand function calls in a string?
How do I find matching/nesting anything?
How do I reverse a string?
How do I expand tabs in a string?
How do I reformat a paragraph?
How can I access/change the first N letters of a string?
How do I change the Nth occurrence of something?
How can I count the number of occurrences of a substring within a string?
How do I capitalize all the words on one line?
How can I split a [character] delimited string except when inside [character]? (Comma-separated files)
How do I strip blank space from the beginning/end of a string?
How do I extract selected columns from a string?
How do I find the soundex value of a string?
How can I expand variables in text strings?
What's wrong with always quoting "$vars"?
Why don't my <<HERE documents work?

1. There must be no space after the << part, 2. There (probably) should be a semicolon at the end, 3. You can't (easily) have any space in front of the tag
Data: Arrays
What is the difference between $array[1] and @array[1]?
How can I extract just the unique elements of an array?

a) If @in is sorted, and you want @out to be sorted:(this assumes all true values in the array), b) If you don't know whether @in is sorted:, c) Like (b), but @in contains only small integers:, d) A way to do (b) without any loops or greps:, e) Like (d), but @in contains only small positive integers:

How can I tell whether a list or array contains a certain element?
How do I compute the difference of two arrays? How do I compute the intersection of two arrays?
How do I find the first array element for which a condition is true?
How do I handle linked lists?
How do I handle circular lists?
How do I shuffle an array randomly?
How do I process/modify each element of an array?
How do I select a random element from an array?
How do I permute N elements of a list?
How do I sort an array by (anything)?
How do I manipulate arrays of bits?
Why does defined() return true on empty arrays and hashes?
Data: Hashes (Associative Arrays)
How do I process an entire hash?
What happens if I add or remove keys from a hash while iterating over it?
How do I look up a hash element by value?
How can I know how many entries are in a hash?
How do I sort a hash (optionally by value instead of key)?
How can I always keep my hash sorted?
What's the difference between "delete" and "undef" with hashes?
Why don't my tied hashes make the defined/exists distinction?
How do I reset an each() operation part-way through?
How can I get the unique keys from two hashes?
How can I store a multidimensional array in a DBM file?
How can I make my hash remember the order I put elements into it?
Why does passing a subroutine an undefined element in a hash create it?
How can I make the Perl equivalent of a C structure/C++ class/hash or array of hashes or arrays?
How can I use a reference as a hash key?
Data: Misc
How do I handle binary data correctly?
How do I determine whether a scalar is a number/whole/integer/float?
How do I keep persistent data across program calls?
How do I print out or copy a recursive data structure?
How do I define methods for every class/object?
How do I verify a credit card checksum?

perlfaq5 - Files and Formats ($Revision: 1.24 $, $Date: 1998/07/05 15:07:20 $)

How do I flush/unbuffer an output filehandle? Why must I do this?
How do I change one line in a file/delete a line in a file/insert a line in the middle of a file/append to the beginning of a file?
How do I count the number of lines in a file?
How do I make a temporary file name?
How can I manipulate fixed-record-length files?
How can I make a filehandle local to a subroutine? How do I pass filehandles between subroutines? How do I make an array of filehandles?
How can I use a filehandle indirectly?
How can I set up a footer format to be used with write()?
How can I write() into a string?
How can I output my numbers with commas added?
How can I translate tildes (~) in a filename?
How come when I open a file read-write it wipes it out?
Why do I sometimes get an "Argument list too long" when I use <*>?
Is there a leak/bug in glob()?
How can I open a file with a leading "gt" or trailing blanks?
How can I reliably rename a file?
How can I lock a file?
What can't I just open(FH, ">file.lock")?
I still don't get locking. I just want to increment the number in the file. How can I do this?
How do I randomly update a binary file?
How do I get a file's timestamp in perl?
How do I set a file's timestamp in perl?
How do I print to more than one file at once?
How can I read in a file by paragraphs?
How can I read a single character from a file? From the keyboard?
How can I tell if there's a character waiting on a filehandle?
How do I do a tail -f in perl?
How do I dup() a filehandle in Perl?
How do I close a file descriptor by number?
Why can't I use "C:\temp\foo" in DOS paths? What doesn't `C:\temp\foo.exe` work?
Why doesn't glob("*.*") get all the files?
Why does Perl let me delete read-only files? Why does -i clobber protected files? Isn't this a bug in Perl?
How do I select a random line from a file?

perlfaq6 - Regexps ($Revision: 1.22 $, $Date: 1998/07/16 14:01:07 $)

How can I hope to use regular expressions without creating illegible and unmaintainable code?

Comments Outside the Regexp, Comments Inside the Regexp, Different Delimiters

I'm having trouble matching over more than one line. What's wrong?
How can I pull out lines between two patterns that are themselves on different lines?
I put a regular expression into $/ but it didn't work. What's wrong?
How do I substitute case insensitively on the LHS, but preserving case on the RHS?
How can I make \w match national character sets?
How can I match a locale-smart version of /[a-zA-Z]/?
How can I quote a variable to use in a regexp?
What is /o really for?
How do I use a regular expression to strip C style comments from a file?
Can I use Perl regular expressions to match balanced text?
What does it mean that regexps are greedy? How can I get around it?
How do I process each word on each line?
How can I print out a word-frequency or line-frequency summary?
How can I do approximate matching?
How do I efficiently match many regular expressions at once?
Why don't word-boundary searches with \b work for me?
Why does using $&, $`, or $' slow my program down?
What good is \G in a regular expression?
Are Perl regexps DFAs or NFAs? Are they POSIX compliant?
What's wrong with using grep or map in a void context?
How can I match strings with multibyte characters?

perlfaq7 - Perl Language Issues ($Revision: 1.21 $, $Date: 1998/06/22 15:20:07 $)

Can I get a BNF/yacc/RE for the Perl language?
What are all these $@%* punctuation signs, and how do I know when to use them?
Do I always/never have to quote my strings or use semicolons and commas?
How do I skip some return values?
How do I temporarily block warnings?
What's an extension?
Why do Perl operators have different precedence than C operators?
How do I declare/create a structure?
How do I create a module?
How do I create a class?
How can I tell if a variable is tainted?
What's a closure?
What is variable suicide and how can I prevent it?
How can I pass/return a {Function, FileHandle, Array, Hash, Method, Regexp}?

Passing Variables and Functions, Passing Filehandles, Passing Regexps, Passing Methods

How do I create a static variable?
What's the difference between dynamic and lexical (static) scoping? Between local() and my()?
How can I access a dynamic variable while a similarly named lexical is in scope?
What's the difference between deep and shallow binding?
Why doesn't "my($foo) = <FILE>;" work right?
How do I redefine a builtin function, operator, or method?
What's the difference between calling a function as &foo and foo()?
How do I create a switch or case statement?
How can I catch accesses to undefined variables/functions/methods?
Why can't a method included in this same file be found?
How can I find out my current package?
How can I comment out a large block of perl code?

perlfaq8 - System Interaction ($Revision: 1.25 $, $Date: 1998/07/05 15:07:20 $)

How do I find out which operating system I'm running under?
How come exec() doesn't return?
How do I do fancy stuff with the keyboard/screen/mouse?

Keyboard, Screen, Mouse

How do I print something out in color?
How do I read just one key without waiting for a return key?
How do I check whether input is ready on the keyboard?
How do I clear the screen?
How do I get the screen size?
How do I ask the user for a password?
How do I read and write the serial port?

lockfiles, open mode, end of line, flushing output, non-blocking input

How do I decode encrypted password files?
How do I start a process in the background?

STDIN, STDOUT, and STDERR are shared, Signals, Zombies

How do I trap control characters/signals?
How do I modify the shadow password file on a Unix system?
How do I set the time and date?
How can I sleep() or alarm() for under a second?
How can I measure time under a second?
How can I do an atexit() or setjmp()/longjmp()? (Exception handling)
Why doesn't my sockets program work under System V (Solaris)? What does the error message "Protocol not supported" mean?
How can I call my system's unique C functions from Perl?
Where do I get the include files to do ioctl() or syscall()?
Why do setuid perl scripts complain about kernel problems?
How can I open a pipe both to and from a command?
Why can't I get the output of a command with system()?
How can I capture STDERR from an external command?
Why doesn't open() return an error when a pipe open fails?
What's wrong with using backticks in a void context?
How can I call backticks without shell processing?
Why can't my script read from STDIN after I gave it EOF (^D on Unix, ^Z on MS-DOS)?
How can I convert my shell script to perl?
Can I use perl to run a telnet or ftp session?
How can I write expect in Perl?
Is there a way to hide perl's command line from programs such as "ps"?
I {changed directory, modified my environment} in a perl script. How come the change disappeared when I exited the script? How do I get my changes to be visible?


How do I close a process's filehandle without waiting for it to complete?
How do I fork a daemon process?
How do I make my program run with sh and csh?
How do I find out if I'm running interactively or not?
How do I timeout a slow event?
How do I set CPU limits?
How do I avoid zombies on a Unix system?
How do I use an SQL database?
How do I make a system() exit on control-C?
How do I open a file without blocking?
How do I install a CPAN module?
What's the difference between require and use?
How do I keep my own module/library directory?
How do I add the directory my program lives in to the module/library search path?
How do I add a directory to my include path at runtime?

perlfaq9 - Networking ($Revision: 1.20 $, $Date: 1998/06/22 18:31:09 $)

My CGI script runs from the command line but not the browser. (500 Server Error)
How can I get better error messages from a CGI program?
How do I remove HTML from a string?
How do I extract URLs?
How do I download a file from the user's machine? How do I open a file on another machine?
How do I make a pop-up menu in HTML?
How do I fetch an HTML file?
How do I automate an HTML form submission?
How do I decode or create those %-encodings on the web?
How do I redirect to another page?
How do I put a password on my web pages?
How do I edit my .htpasswd and .htgroup files with Perl?
How do I make sure users can't enter values into a form that cause my CGI script to do bad things?
How do I parse a mail header?
How do I decode a CGI form?
How do I check a valid mail address?
How do I decode a MIME/BASE64 string?
How do I return the user's mail address?
How do I send mail?
How do I read mail?
How do I find out my hostname/domainname/IP address?
How do I fetch a news article or the active newsgroups?
How do I fetch/put an FTP file?
How can I do RPC in Perl?

perldelta - what's new for perl5.005

About the new versioning system
Incompatible Changes
WARNING: This version is not binary compatible with Perl 5.004.
Default installation structure has changed
Perl Source Compatibility
C Source Compatibility

Core sources now require ANSI C compiler, All Perl global variables must now be referenced with an explicit prefix, Enabling threads has source compatibility issues

Binary Compatibility
Security fixes may affect compatibility
Relaxed new mandatory warnings introduced in 5.004
Core Changes
Regular Expressions

Many new and improved optimizations, Many bug fixes, New regular expression constructs, New operator for precompiled regular expressions, Other improvements, Incompatible changes

Improved malloc()
Quicksort is internally implemented
Reliable signals
Reliable stack pointers
More generous treatment of carriage returns
Memory leaks
Better support for multiple interpreters
Behavior of local() on array and hash elements is now well-defined
%! is transparently tied to the Errno module
Pseudo-hashes are supported
EXPR foreach EXPR is supported
Keywords can be globally overridden
$^E is meaningful on Win32
foreach (1..1000000) optimized
Foo:: can be used as implicitly quoted package name
exists $Foo::{Bar::} tests existence of a package
Better locale support
Experimental support for 64-bit platforms
prototype() returns useful results on builtins
Extended support for exception handling
Re-blessing in DESTROY() supported for chaining DESTROY() methods
All printf format conversions are handled internally
New INIT keyword
New lock keyword
New qr// operator
our is now a reserved word
Tied arrays are now fully supported
Tied handles support is better
  • th argument to substr
    Negative LENGTH argument to splice
    Magic lvalues are now more magical
    ltgt now reads in records
  • Supported Platforms
    New Platforms
    Changes in existing support
    Modules and Pragmata
    New Modules

    B, Data::Dumper, Errno, File::Spec, ExtUtils::Installed, ExtUtils::Packlist, Fatal, IPC::SysV, Test, Tie::Array, Tie::Handle, Thread, attrs, fields, re

    Changes in existing modules

    CGI, POSIX, DB_File, MakeMaker, CPAN, Cwd, Benchmark
    Utility Changes
    Documentation Changes
    New Diagnostics

    Ambiguous call resolved as CORE::%s(), qualify as such or use &, Bad index while coercing array into hash, Bareword ``%s'' refers to nonexistent package, Can't call method ``%s'' on an undefined value, Can't coerce array into hash, Can't goto subroutine from an eval-string, Can't localize pseudo-hash element, Can't use %%! because is not available, Cannot find an opnumber for ``%s'', Character class syntax [. .] is reserved for future extensions, Character class syntax [: :] is reserved for future extensions, Character class syntax [= =] is reserved for future extensions, %s: Eval-group in insecure regular expression, %s: Eval-group not allowed, use re 'eval', %s: Eval-group not allowed at run time, Explicit blessing to '' (assuming package main), Illegal hex digit ignored, No such array field, No such field ``%s'' in variable %s of type %s, Out of memory during ridiculously large request, Range iterator outside integer range, Recursive inheritance detected while looking for method '%s' in package '%s', Reference found where even-sized list expected, Undefined value assigned to typeglob, Use of reserved word ``%s'' is deprecated, perl: warning: Setting locale failed

    Obsolete Diagnostics

    Can't mktemp(), Can't write to temp file for -e: %s, Cannot open temporary file


    perldata - Perl data types

    Variable names
    Scalar values
    Scalar value constructors
    List value constructors
    Typeglobs and Filehandles

    perlsyn - Perl syntax

    Simple statements
    Compound statements
    Loop Control
    For Loops
    Foreach Loops
    Basic BLOCKs and Switch Statements
    PODs: Embedded Documentation
    Plain Old Comments (Not!)

    perlop - Perl operators and precedence

    Terms and List Operators (Leftward)
    The Arrow Operator
    Auto-increment and Auto-decrement
    Symbolic Unary Operators
    Binding Operators
    Multiplicative Operators
    Additive Operators
    Shift Operators
    Named Unary Operators
    Relational Operators
    Equality Operators
    Bitwise And
    Bitwise Or and Exclusive Or
    C-style Logical And
    C-style Logical Or
    Range Operators
    Conditional Operator
    Assignment Operators
    Comma Operator
    List Operators (Rightward)
    Logical Not
    Logical And
    Logical or and Exclusive Or
    C Operators Missing From Perl

    unary &, unary *, (TYPE)

    Quote and Quote-like Operators
    Regexp Quote-Like Operators


    Gory details of parsing quoted constructs

    Finding the end, Removal of backslashes before delimiters, Interpolation, <<'EOF', perlman:perlop, perlman:perlop, perlman:perlop, perlman:perlop, '', perlman:perlop, "", ``, perlman:perlop, perlman:perlop, <file*glob>, ?RE?, /RE/, m/RE/, s/RE/foo/,, Interpolation of regular expressions, Optimization of regular expressions

    I/O Operators
    Constant Folding
    Bitwise String Operators
    Integer Arithmetic
    Floating-point Arithmetic
    Bigger Numbers

    perlre - Perl regular expressions


    i, m, s, x
    Regular Expressions

    (?#text), (?:pattern), (?imsx-imsx:pattern), (?=pattern), (?!pattern), (?<=pattern), (?<!pattern), (?{ code }), (?>pattern), (?(condition)yes-pattern|no-pattern), (?(condition)yes-pattern), (?imsx-imsx)

    Version 8 Regular Expressions
    WARNING on \1 vs $1
    Repeated patterns matching zero-length substring
    Creating custom RE engines

    perlrun - how to execute the Perl interpreter

    1. OS/2, MS-DOS, Win95/NT, Macintosh

      Location of Perl

      -0[digits], -a, -c, -d, -d:foo, -Dletters, -Dnumber, -e commandline, -Fpattern, -h, -i[extension], -Idirectory, -l[octnum], -m[-]module, -M[-]module, -M[-]'module ...', -[mM][-]module=arg[,arg]..., -n, -p, -P, -s, -S, -T, -u, -U, -v, -V, -V:name, -w, -x directory


    perlfunc - Perl builtin functions

    Perl Functions by Category

    Functions for SCALARs or strings, Regular expressions and pattern matching, Numeric functions, Functions for real @ARRAYs, Functions for list data, Functions for real %HASHes, Input and output functions, Functions for fixed length data or records, Functions for filehandles, files, or directories, Keywords related to the control flow of your perl program, Keywords related to scoping, Miscellaneous functions, Functions for processes and process groups, Keywords related to perl modules, Keywords related to classes and object-orientedness, Low-level socket functions, System V interprocess communication functions, Fetching user and group info, Fetching network info, Time-related functions, Functions new in perl5, Functions obsoleted in perl5

    Alphabetical Listing of Perl Functions

    -X FILEHANDLE, -X EXPR, -X, abs VALUE, abs, accept NEWSOCKET,GENERICSOCKET, alarm SECONDS, alarm, atan2 Y,X, bind SOCKET,NAME, binmode FILEHANDLE, bless REF,CLASSNAME, bless REF, caller EXPR, caller, chdir EXPR, chmod LIST, chomp VARIABLE, chomp LIST, chomp, chop VARIABLE, chop LIST, chop, chown LIST, chr NUMBER, chr, chroot FILENAME, chroot, close FILEHANDLE, close, closedir DIRHANDLE, connect SOCKET,NAME, continue BLOCK, cos EXPR, crypt PLAINTEXT,SALT, dbmclose HASH, dbmopen HASH,DBNAME,MODE, defined EXPR, defined, delete EXPR, die LIST, do BLOCK, do SUBROUTINE(LIST), do EXPR, dump LABEL, each HASH, eof FILEHANDLE, eof (), eof, eval EXPR, eval BLOCK, exec LIST, exec PROGRAM LIST, exists EXPR, exit EXPR, exp EXPR, exp, fcntl FILEHANDLE,FUNCTION,SCALAR, fileno FILEHANDLE, flock FILEHANDLE,OPERATION, fork, format, formline PICTURE,LIST, getc FILEHANDLE, getc, getlogin, getpeername SOCKET, getpgrp PID, getppid, getpriority WHICH,WHO, getpwnam NAME, getgrnam NAME, gethostbyname NAME, getnetbyname NAME, getprotobyname NAME, getpwuid UID, getgrgid GID, getservbyname NAME,PROTO, gethostbyaddr ADDR,ADDRTYPE, getnetbyaddr ADDR,ADDRTYPE, getprotobynumber NUMBER, getservbyport PORT,PROTO, getpwent, getgrent, gethostent, getnetent, getprotoent, getservent, setpwent, setgrent, sethostent STAYOPEN, setnetent STAYOPEN, setprotoent STAYOPEN, setservent STAYOPEN, endpwent, endgrent, endhostent, endnetent, endprotoent, endservent, getsockname SOCKET, getsockopt SOCKET,LEVEL,OPTNAME, glob EXPR, glob, gmtime EXPR, goto LABEL, goto EXPR, goto &NAME, grep BLOCK LIST, grep EXPR,LIST, hex EXPR, hex, import, index STR,SUBSTR,POSITION, index STR,SUBSTR, int EXPR, int, ioctl FILEHANDLE,FUNCTION,SCALAR, join EXPR,LIST, keys HASH, kill LIST, last LABEL, last, lc EXPR, lc, lcfirst EXPR, lcfirst, length EXPR, length, link OLDFILE,NEWFILE, listen SOCKET,QUEUESIZE, local EXPR, localtime EXPR, log EXPR, log, lstat FILEHANDLE, lstat EXPR, lstat, m//, map BLOCK LIST, map EXPR,LIST, mkdir FILENAME,MODE, msgctl ID,CMD,ARG, msgget KEY,FLAGS, msgsnd ID,MSG,FLAGS, msgrcv ID,VAR,SIZE,TYPE,FLAGS, my EXPR, next LABEL, next, no Module LIST, oct EXPR, oct, open FILEHANDLE,EXPR, open FILEHANDLE, opendir DIRHANDLE,EXPR, ord EXPR, ord, pack TEMPLATE,LIST, package, package NAMESPACE, pipe READHANDLE,WRITEHANDLE, pop ARRAY, pop, pos SCALAR, pos, print FILEHANDLE LIST, print LIST, print, printf FILEHANDLE FORMAT, LIST, printf FORMAT, LIST, prototype FUNCTION, push ARRAY,LIST, q/STRING/, qq/STRING/, qr/STRING/, qx/STRING/, qw/STRING/, quotemeta EXPR, quotemeta, rand EXPR, rand, read FILEHANDLE,SCALAR,LENGTH,OFFSET, read FILEHANDLE,SCALAR,LENGTH, readdir DIRHANDLE, readline EXPR, readlink EXPR, readlink, readpipe EXPR, recv SOCKET,SCALAR,LEN,FLAGS, redo LABEL, redo, ref EXPR, ref, rename OLDNAME,NEWNAME, require EXPR, require, reset EXPR, reset, return EXPR, return, reverse LIST, rewinddir DIRHANDLE, rindex STR,SUBSTR,POSITION, rindex STR,SUBSTR, rmdir FILENAME, rmdir, s///, scalar EXPR, seek FILEHANDLE,POSITION,WHENCE, seekdir DIRHANDLE,POS, select FILEHANDLE, select, select RBITS,WBITS,EBITS,TIMEOUT, semctl ID,SEMNUM,CMD,ARG, semget KEY,NSEMS,FLAGS, semop KEY,OPSTRING, send SOCKET,MSG,FLAGS,TO, send SOCKET,MSG,FLAGS, setpgrp PID,PGRP, setpriority WHICH,WHO,PRIORITY, setsockopt SOCKET,LEVEL,OPTNAME,OPTVAL, shift ARRAY, shift, shmctl ID,CMD,ARG, shmget KEY,SIZE,FLAGS, shmread ID,VAR,POS,SIZE, shmwrite ID,STRING,POS,SIZE, shutdown SOCKET,HOW, sin EXPR, sin, sleep EXPR, sleep, socket SOCKET,DOMAIN,TYPE,PROTOCOL, socketpair SOCKET1,SOCKET2,DOMAIN,TYPE,PROTOCOL, sort SUBNAME LIST, sort BLOCK LIST, sort LIST, splice ARRAY,OFFSET,LENGTH,LIST, splice ARRAY,OFFSET,LENGTH, splice ARRAY,OFFSET, split /PATTERN/,EXPR,LIMIT, split /PATTERN/,EXPR, split /PATTERN/, split, sprintf FORMAT, LIST, sqrt EXPR, sqrt, srand EXPR, srand, stat FILEHANDLE, stat EXPR, stat, study SCALAR, study, sub BLOCK, sub NAME, sub NAME BLOCK, substr EXPR,OFFSET,LEN,REPLACEMENT, substr EXPR,OFFSET,LEN, substr EXPR,OFFSET, symlink OLDFILE,NEWFILE, syscall LIST, sysopen FILEHANDLE,FILENAME,MODE, sysopen FILEHANDLE,FILENAME,MODE,PERMS, sysread FILEHANDLE,SCALAR,LENGTH,OFFSET, sysread FILEHANDLE,SCALAR,LENGTH, sysseek FILEHANDLE,POSITION,WHENCE, system LIST, system PROGRAM LIST, syswrite FILEHANDLE,SCALAR,LENGTH,OFFSET, syswrite FILEHANDLE,SCALAR,LENGTH, tell FILEHANDLE, tell, telldir DIRHANDLE, tie VARIABLE,CLASSNAME,LIST, tied VARIABLE, time, times, tr///, truncate FILEHANDLE,LENGTH, truncate EXPR,LENGTH, uc EXPR, uc, ucfirst EXPR, ucfirst, umask EXPR, umask, undef EXPR, undef, unlink LIST, unlink, unpack TEMPLATE,EXPR, untie VARIABLE, unshift ARRAY,LIST, use Module LIST, use Module, use Module VERSION LIST, use VERSION, utime LIST, values HASH, vec EXPR,OFFSET,BITS, wait, waitpid PID,FLAGS, wantarray, warn LIST, write FILEHANDLE, write EXPR, write, y///

    perlvar - Perl predefined variables

    Predefined Names

    $ARG, $_, $<digits>, $MATCH, $&, $PREMATCH, $`, $POSTMATCH, $', $LAST_PAREN_MATCH, $+, $MULTILINE_MATCHING, $*, input_line_number HANDLE EXPR, $INPUT_LINE_NUMBER, $NR, $, input_record_separator HANDLE EXPR, $INPUT_RECORD_SEPARATOR, $RS, $/, autoflush HANDLE EXPR, $OUTPUT_AUTOFLUSH, $|, output_field_separator HANDLE EXPR, $OUTPUT_FIELD_SEPARATOR, $OFS, $,, output_record_separator HANDLE EXPR, $OUTPUT_RECORD_SEPARATOR, $ORS, $\, $LIST_SEPARATOR, $``, $SUBSCRIPT_SEPARATOR, $SUBSEP, $;, $OFMT, $#, format_page_number HANDLE EXPR, $FORMAT_PAGE_NUMBER, $%, format_lines_per_page HANDLE EXPR, $FORMAT_LINES_PER_PAGE, $=, format_lines_left HANDLE EXPR, $FORMAT_LINES_LEFT, $-, format_name HANDLE EXPR, $FORMAT_NAME, $~, format_top_name HANDLE EXPR, $FORMAT_TOP_NAME, $^, format_line_break_characters HANDLE EXPR, $FORMAT_LINE_BREAK_CHARACTERS, $:, format_formfeed HANDLE EXPR, $FORMAT_FORMFEED, $^L, $ACCUMULATOR, $^A, $CHILD_ERROR, $?, $OS_ERROR, $ERRNO, $!, $EXTENDED_OS_ERROR, $^E, $EVAL_ERROR, $@, $PROCESS_ID, $PID, $$, $REAL_USER_ID, $UID, $<, $EFFECTIVE_USER_ID, $EUID, $>, $REAL_GROUP_ID, $GID, $(, $EFFECTIVE_GROUP_ID, $EGID, $), $PROGRAM_NAME, $0, $[, $PERL_VERSION, $], $DEBUGGING, $^D, $SYSTEM_FD_MAX, $^F, $^H, $INPLACE_EDIT, $^I, $^M, $OSNAME, $^O, $PERLDB, $^P, 0x01, 0x02, 0x04, 0x08, 0x10, 0x20, $^R, $^S, $BASETIME, $^T, $WARNING, $^W, $EXECUTABLE_NAME, $^X, $ARGV, @ARGV, @INC, @_, %INC, %ENV $ENV{expr}, %SIG $SIG{expr}

    Error Indicators

    perlsub - Perl subroutines

    Private Variables via my()
    Peristent Private Variables
    Temporary Values via local()
    Passing Symbol Table Entries (typeglobs)
    When to Still Use local()

    1. You need to give a global variable a temporary value, especially $_, 2. You need to create a local file or directory handle or a local function, 3. You want to temporarily change just one element of an array or hash

    Pass by Reference
    Constant Functions
    Overriding Builtin Functions

    perlmod - Perl modules (packages and symbol tables)

    Symbol Tables
    Package Constructors and Destructors
    Perl Classes
    Perl Modules

    perlmodlib - constructing new Perl modules and finding existing ones


    Return to the Library
    Log In?

    What's my password?
    Create A New User
    Domain Nodelet?
    and the web crawler heard nothing...

    How do I use this?Last hourOther CB clients
    Other Users?
    Others learning in the Monastery: (2)
    As of 2024-07-22 01:21 GMT
    Find Nodes?
      Voting Booth?

      No recent polls found

      erzuuli‥ 🛈The London Perl and Raku Workshop takes place on 26th Oct 2024. If your company depends on Perl, please consider sponsoring and/or attending.