Standard Modules
Contents:
AnyDBM_File
attrs
AutoLoader
AutoSplit
autouse
B
Asmdata
Assembler
Bblock
Bytecode
C
CC
Debug
Deparse
Disassembler
Lint
Showlex
Stackobj
Terse
Xref
base
Benchmark
blib
Carp
CGI
CGI::Apache
CGI::Carp
CGI::Cookie
CGI::Fast
CGI::Push
CGI::Switch
Class::Struct
Config
constant
CPAN
CPAN::FirstTime
CPAN::Nox
Cwd
Data::Dumper
DB_File
Devel::SelfStubber
diagnostics
DirHandle
DynaLoader
English
Env
Errno
Exporter
ExtUtils::Command
ExtUtils::Embed
ExtUtils::Install
ExtUtils::Installed
ExtUtils::Liblist
ExtUtils::MakeMaker
ExtUtils::Manifest
ExtUtils::Miniperl
ExtUtils::Mkbootstrap
ExtUtils::Mksymlists
ExtUtils::MM_OS2
ExtUtils::MM_Unix
ExtUtils::MM_VMS
ExtUtils::MM_Win32
ExtUtils::Packlist
ExtUtils::testlib
Fatal
Fcntl
fields
File::Basename
File::CheckTree
File::Compare
File::Copy
File::DosGlob
File::Find
File::Path
File::Spec
File::Spec::Mac
File::Spec::OS2
File::Spec::Unix
File::Spec::VMS
File::Spec::Win32
File::stat
FileCache
FileHandle
FindBin
GDBM_File
Getopt::Long
Getopt::Std
Collate
integer
IO
IO::File
IO::Handle
IO::Pipe
IO::Seekable
IO::Select
IO::Socket
IPC::Msg
IPC::Open2
IPC::Open3
IPC::Semaphore
IPC::SysV
less
lib
locale
Math::BigFloat
Math::BigInt
Math::Complex
Math::Trig
NDBM_File
Net::hostent
Net::netent
Net::Ping
Net::protoent
Net::servent
O
ODBM_File
Opcode
ops
overload
Pod::Functions
Pod::Html
Pod::Text
POSIX
re
Safe
SDBM_File
Search::Dict
SelectSaver
SelfLoader
Shell
sigtrap
Socket
strict
subs
Symbol
Sys::Hostname
Sys::Syslog
Term::Cap
Term::Complete
Term::ReadLine
Test
Test::Harness
Text::Abbrev
Text::ParseWords
Text::Soundex
Text::Tabs
Text::Wrap
Thread
Thread::Queue
Thread::Semaphore
Thread::Signal
Thread::Specific
Tie::Array, Tie::StdArray
Tie::Handle
Tie::Hash, Tie::StdHash
Tie::RefHash
Tie::Scalar, Tie::StdScalar
Tie::SubstrHash
Time::gmtime
Time::Local
Time::localtime
Time::tm
UNIVERSAL
User::grent
User::pwent
vars
vmsish
We've talked about the extent to which Perl benefits from user contributions. In fact, many contributed modules are so generally useful that they are now distributed with Perl itself. This chapter describes these "standard modules"-if you are running Perl 5.005, all these modules are already available to you. If you are running an earlier version of Perl, and you find that a module you want isn't on your system, or if you simply don't find what you need among the modules in this chapter, check CPAN for one that does what you want.
While this chapter primarily covers standard Perl modules called at execution time from your program, it also covers the "pragmatic" modules that affect the compilation phase. (A pragma is a compiler directive that provides hints to the compiler.) By convention, the names of the pragmatic modules are all lowercase, while the names of other modules begin with an uppercase letter and are of mixed case.
The Win32-specific modules are not included in this chapter, but are described in Win32 Modules and Extensions.
The following table provides a quick look at the standard modules and what they do:
| Module | Function |
|---|---|
| AnyDBM_File | Provides framework for multiple DBMs |
| attrs | Sets or gets attributes of a subroutine |
| AutoLoader | Loads functions only on demand |
| AutoSplit | Splits a module for autoloading |
| autouse | Postpones load of modules until a function is used |
| B | Perl compiler and tools |
| base | Establishes IS-A relationship with base class at compile time |
| Benchmark | Checks and compares running times of code |
| blib | Uses MakeMaker's uninstalled version of a package |
| Carp | Generates error messages |
| CGI | Simple Common Gateway Interface class |
| CGI::Apache | Sets up environment to use CGI with Perl-Apache API |
| CGI::Carp | CGI routines for writing to HTTPD (or other) error log |
| CGI::Cookie | CGI interface to Netscape (HTTP/1.1) cookies |
| CGI::Fast | CGI interface for FastCGI |
| CGI::Push | Interface for server push operations |
| CGI::Switch | Tries multiple constructors and returns the first available CGI object |
| Class::Struct | Declares struct-like datatypes as Perl classes |
| Config | Accesses Perl configuration information |
| constant | Perl pragma to declare constants |
| CPAN | Queries, downloads, and builds Perl modules from CPAN sites |
| CPAN::FirstTime | Utility for CPAN::Config file initialization |
| CPAN::Nox | Wrapper around CPAN.pm without using any XS module |
| Cwd | Gets pathname of current working directory |
| Data::Dumper | Returns Perl data structures as strings |
| DB_File | Accesses Berkeley DB |
| Devel::SelfStubber | Generates stubs for a selfloading module |
| diagnostics | Forces verbose warning diagnostics |
| DirHandle | Supplies object methods for directory handles |
| DynaLoader | Automatic dynamic loading of Perl modules |
| English | Uses English or awk names for punctuation variables |
| Env | Imports environment variables |
| Errno | System errno constants from errno.h include file |
| Exporter | Default import method for modules |
| ExtUtils::Command | Utilities to replace common Unix commands |
| ExtUtils::Embed | Utilities for embedding Perl in C/C++ applications |
| ExtUtils::Install | Installs files from here to there |
| ExtUtils::Installed | Inventory management of installed modules |
| ExtUtils::Liblist | Determines libraries to use and how to use them |
| ExtUtils::MakeMaker | Creates a Makefile for a Perl extension |
| ExtUtils::Manifest | Utilities to write and check a MANIFEST file |
| ExtUtils::Miniperl | Writes the C code for perlmain.c |
| ExtUtils::Mkbootstrap | Makes a bootstrap file for use by DynaLoader |
| ExtUtils::Mksymlists | Writes linker option files for dynamic extension |
| ExtUtils::MM_OS2 | Methods to override Unix behavior in ExtUtils::MakeMaker |
| ExtUtils::MM_Unix | Methods used by ExtUtils::MakeMaker |
| ExtUtils::MM_VMS | Methods to override Unix behavior in ExtUtils::MakeMaker |
| ExtUtils::MM_Win32 | Methods to override Unix behavior in ExtUtils::MakeMaker |
| ExtUtils::Packlist | Manages .packlist files |
| ExtUtils::testlib | Adds blib/* directories to @INC
|
| Fatal | Replaces functions with equivalents that succeed or die |
| Fcntl | Loads the C fcntl.h defines |
| fields | Perl pragma to provide compile-time verified class fields |
| File::Basename | Parses file specifications |
| File::CheckTree | Runs many tests on a collection of files |
| File::Compare | Compares files or filehandles |
| File::Copy | Copies files or filehandles |
| File::DosGlob | DOS-like globbing with enhancements |
| File::Find | Traverses a file tree |
| File::Path | Creates or removes a series of directories |
| File::Spec | Portably performs operations on filenames |
| File::stat | By-name interface to Perl's built-in stat functions
|
| FileCache | Keeps more files open than the system permits |
| FileHandle | Supplies object methods for filehandles |
| FindBin | Locates directory of original Perl script |
| GDBM_File | Tied access to GDBM library |
| Getopt::Long | Extended processing of command-line options |
| Getopt::Std | Processes single-character options with option clustering |
| Collate | Compares 8-bit scalar data according to the current locale |
| integer | Does arithmetic in integer instead of double |
| IO | Loads various IO modules |
| IO::File | Supplies object methods for filehandles |
| IO::Handle | Supplies object methods for I/O handles |
| IO::Pipe | Supplies object methods for pipes |
| IO::Seekable | Supplies seek-based methods for I/O objects |
| IO::Select | Object-oriented interface to the select system call |
| IO::Socket | Object interface to socket communications |
| IPC::Msg | System V Msg IPC object class |
| IPC::Open2 | Opens a process for both reading and writing |
| IPC::Open3 | Opens a process for reading, writing, and error handling |
| IPC::Semaphore | System V Semaphore IPC object class |
| IPC::SysV | System V IPC constants |
| less | Perl pragma to request less of something from the compiler |
| lib | Manipulates @INC at compile time
|
| locale | Perl pragma to use and avoid POSIX locales for built-in operations |
| Math::BigFloat | Arbitrary-length floating-point math package |
| Math::BigInt | Arbitrary-length integer math package |
| Math::Complex | Complex numbers package |
| Math::Trig | Trigonometric functions |
| NDBM_File | Tied access to NDBM files |
| Net::hostent | By-name interface to Perl's built-in gethost* functions
|
| Net::netent | By-name interface to Perl's built-in getnet* functions
|
| Net::Ping | Checks whether a host is online |
| Net::protoent | By-name interface to Perl's built-in getproto* functions
|
| Net::servent | By-name interface to Perl's built-in getserv* functions
|
| ODBM_File | Tied access to ODBM files |
| Opcode | Disables named opcodes when compiling Perl code |
| ops | Restricts unsafe operations when compiling |
| overload | Overloads Perl's mathematical operations |
| Pod::Functions | Used in converting from pod to HTML |
| Pod::Html | Module to convert pod files to HTML |
| Pod::Text | Converts pod data to formatted ASCII text |
| POSIX | Perl interface to IEEE Std 1003.1 |
| re | Perl pragma to alter regular expression behavior |
| Safe | Creates safe namespaces for evaluating Perl code |
| SDBM_File | Tied access to SDBM files |
| Search::Dict | Searches for key in dictionary file |
| SelectSaver | Saves and restores selected filehandle |
| SelfLoader | Loads functions only on demand |
| Shell | Runs shell commands transparently within Perl |
| sigtrap | Enables stack backtrace on unexpected signals |
| Socket | Loads the C socket.h defines and structure manipulators |
| strict | Restricts unsafe constructs |
| subs | Predeclares subroutine names |
| Symbol | Generates anonymous globs; qualifies variable names |
| Sys::Hostname | Tries every conceivable way to get hostname |
| Sys::Syslog | Perl interface to Unix syslog(3) calls
|
| Term::Cap | Terminal capabilities interface |
| Term::Complete | Word completion module |
| Term::ReadLine | Interface to various ReadLine packages |
| Test | Framework for writing test scripts |
| Test::Harness | Runs Perl standard test scripts with statistics |
| Text::Abbrev | Creates an abbreviation table from a list |
| Text::ParseWords | Parses text into a list of tokens |
| Text::Soundex | The soundex algorithm described by Knuth |
| Text::Tabs | Expands and unexpands tabs |
| Text::Wrap | Wraps text into a paragraph |
| Thread | Multithreading support |
| Thread::Queue | Thread-safe queues |
| Thread::Semaphore | Thread-safe semaphores |
| Thread::Signal | Starts a thread that runs signal handlers reliably |
| Thread::Specific | Thread-specific keys |
| Tie::Array | Base class definitions for tied arrays |
| Tie::Handle | Base class definitions for tied handles |
| Tie::Hash, Tie::StdHash | Base class definitions for tied hashes |
| Tie::RefHash | Uses references as hash keys |
| Tie::Scalar, Tie::StdScalar | Base class definitions for tied scalars |
| Tie::SubstrHash | Fixed-table-size, fixed-key-length hashing |
| Time::gmtime | By-name interface to Perl's built-in gmtime function
|
| Time::Local | Computes time from local and GMT time |
| Time::localtime | By-name interface to Perl's built-in localtime function
|
| Time::tm | Internal object used by Time::gmtime and Time::localtime |
| UNIVERSAL | Base class for all classes (blessed references) |
| User::grent | By-name interface to Perl's built-in getgr* functions
|
| User::pwent | By-name interface to Perl's built-in getpw* functions
|
| vars | Predeclares global variable names |
| vmsish | Enables VMS-specific language features |
In the remainder of this chapter, the modules are arranged in alphabetical order for easy reference. For more detail about a module, use the perldoc command to read the manpage for that module (see The Perl Language, for information on perldoc).
AnyDBM_File
Provides a single DBM (Database Manager) interface regardless of the DBM implementation you use. The module inherits from the various DBM packages; by default, it inherits from NDBM_File. If it doesn't find NDBM_File, the default search order is: DB_File, GDBM_File, SDBM_File (which comes with Perl), and finally ODBM_File. You can override this default order by redefining @ISA:
@AnyDBM_File::ISA = qw(DB_File GDBM_File NDBM_File);
However, an explicit
use takes priority over the @ISA ordering.
Perl's dbmopen function actually just calls tie to bind a hash to AnyDBM_File. The effect is to bind the hash to one of the specific DBM classes that AnyDBM_File inherits from.