Perl
From Wikipedia:
- Perl is a high-level, general-purpose, interpreted, dynamic programming language.
- Perl borrows features from other programming languages including C, sh, AWK, and sed. It provides text processing facilities without the arbitrary data-length limits of many contemporary Unix command line tools.
- Perl gained widespread popularity in the mid-1990s as a CGI scripting language, in part due to its powerful regular expression and string parsing abilities.
Installation
Commands
The Perl language interpreter:
$ perl
Perl bug reporting:
$ perlbug
Lookup the Perl documentation in POD format:
$ perldoc
Send the Perl authors and maintainers a thank you message:
$ perlthanks
Package management
The Comprehensive Perl Archive Network (CPAN) is a repository of over 250,000 software modules and accompanying documentation written in the Perl programming language by over 12,000 contributors.
CPAN is also the name of a Perl module, CPAN.pm, which is used to download and install Perl software from the CPAN archive.
pacman and AUR
A number of popular CPAN modules are available as packages in the Arch repositories. There are further modules available in the AUR.
CPAN.pm
The CPAN.pm module is included with Perl. It can be used interactively from the shell or in Perl scripts.
Configuring cpan
Before first use, the module needs to be configured. This is done interactively from the shell with (some output omitted):
$ cpan
CPAN.pm requires configuration, but most of it can be done automatically. If you answer 'no' below, you will enter an interactive dialog for each configuration option instead. Would you like to configure as much as possible automatically? [yes]
Automated configuration will suit most users. Answering yes, the configuration will continue with:
To install modules, you need to configure a local Perl library directory or escalate your privileges. CPAN can help you by bootstrapping the local::lib module or by configuring itself to use 'sudo' (if available). You may also resolve this problem manually if you need to customize your setup. What approach do you want? (Choose 'local::lib', 'sudo' or 'manual') [local::lib]
If you want cpan to install modules in your home directory choose local::lib. To install them system-wide choose sudo. Choosing sudo the configuration ends:
Autoconfiguration complete. commit: wrote '/home/username/.cpan/CPAN/MyConfig.pm'
Choosing the local::lib option will result in addition modules being installed.
Choosing not to use automated configuration allows the user to set cpan options interactively in the shell. The table below shows some option names with a brief description and default value. More detailed information is displayed for each option during configuration.
| Name | Description | Default |
|---|---|---|
| cpan_home | CPAN build and cache directory | $HOME/.cpan |
| keep_source_where | Download target directory | $HOME/.cpan/sources |
| build_dir | Build process directory | $HOME/.cpan/build |
| prefs_dir | Customizable modules options directory | $HOME/.cpan/prefs |
| build_cache | Cache size for build directory | 100MB |
| cleanup_after_install | Remove build directory after successful install | No |
| shell | Preferred shell | /bin/bash |
| halt_on_failure | Halt on failure | No |
| colorize_output | Turn on colored output | No |
| histfile | History file location | $HOME/.cpan/histfile |
| histsize | History file size | 100 lines |
The configuration file $HOME/.cpan/CPAN/MyConfig.pm can be edited with your text editor of choice.
Usage examples
To simply install a modules pass them as parameters to cpan (multiple module names are separated by spaces):
$ cpan Acme::MetaSyntactic
The following examples are all in the cpan interactive shell, started with:
$ cpan
Display information on a module:
cpan[1]> m Acme::MetaSyntactic
Reading '/home/username/.cpan/Metadata'
Database was generated on Fri, 08 Dec 2017 02:17:03 GMT
Module id = Acme::MetaSyntactic
CPAN_USERID BOOK (Philippe Bruhat (BooK) <book@cpan.org>)
CPAN_VERSION 1.014
CPAN_FILE B/BO/BOOK/Acme-MetaSyntactic-1.014.tar.gz
INST_FILE (not installed)
View module README:
cpan[2]> readme Acme::MetaSyntactic
Acme::MetaSyntactic - Themed metasyntactic variables DESCRIPTION When writing code examples, it's always easy at the beginning: my $foo = "bar"; $foo .= "baz"; # barbaz ...
Install a module:
cpan[3]> install Acme::MetaSyntactic
Re-run cpan configuration:
cpan[1]> o conf init
Widget bindings
The following widget toolkit bindings are available:
- gtk2-perl — GTK2 bindings
- perl-gtk3 — GTK3 bindings
- Perl/TK — Tk bindings
- wxPerl — wxWidgets bindings
- http://www.wxperl.it/ || perl-wxAUR
- Prima — a perl multiplatform graphic toolkit
To use these with Perl, you may need to install the associated widget kits.
IDE support
Development in JetBrains IDE
If you are using a JetBrains IDE, for example IntelliJ Idea, install perl-bundle-camelcadeAUR. Then install Perl plugin. Then go to the Settings > Languages & Frameworks > Perl5. In the Perl 5 Interpreter field select Add System Perl. Now you can make a run/debug configuration for your project and start debugging.
Tips and tricks
Perl development environment
perlbrew and plenvAUR automate the installation and management of multiple perl versions under your home directory, allowing you to install modules locally without conflicting with the system perl.
Improved module management
cpanminus
cpanminus extends module management, aims to be zero configuration, and integrates with local::lib.
Install the cpanminus package.
See the cpanminus documentation for examples.
ucpan
ucpan is an updater for CPAN modules (especially installed in local-lib). To install, run:
$ cpan App::ucpan
Bundle::CPAN
Installing the Bundle::CPAN distribution will add a lot of nice functionality to CPAN.pm.
$ cpan Bundle::CPAN
See also
Perl
CPAN
- Comprehensive Perl Archive Network
- wikipedia:CPAN
- CPAN / CPAN Shell / CPANPLUS Quick Reference Guide
- List of recommended Perl modules