App::Cmd(3)

NAME
App::Cmd - write command line apps with less suffering

VERSION
version 0.340

SYNOPSIS
in yourcmd:

  use YourApp;
  YourApp->run;

in YourApp.pm:

  package YourApp;
  use App::Cmd::Setup -app;
  1;

in YourApp/Command/blort.pm:

  package YourApp::Command::blort;
  use YourApp -command;
  use strict; use warnings;

  sub abstract { "blortex algorithm" }

  sub description { "Long description on blortex algorithm" }

  sub opt_spec {
    return (
      [ "blortex|X",  "use the blortex algorithm" ],
      [ "recheck|r",  "recheck all results"       ],
    );
  }

  sub validate_args {
    my ($self, $opt, $args) = @_;

    # no args allowed but options!
    $self->usage_error("No args allowed") if @$args;
  }

  sub execute {
    my ($self, $opt, $args) = @_;

    my $result = $opt->{blortex} ? blortex() : blort();

    recheck($result) if $opt->{recheck};

    print $result;
  }

and, finally, at the command line:

  knight!rjbs$ yourcmd blort --recheck

  All blorts successful.

DESCRIPTION
App::Cmd is intended to make it easy to write complex command-line applications without having to think about most of the annoying things usually involved.

For information on how to start using App::Cmd, see App::Cmd::Tutorial.

PERL VERSION
This library should run on perls released even a long time ago. It should work on any version of perl released in the last five years.

Although it may work on older versions of perl, no guarantee is made that the minimum required version will not be increased. The version may be increased for any reason, and there is no promise that patches will be accepted to lower the minimum required perl.

METHODS

  new
  my $cmd = App::Cmd->new(\%arg);

This method returns a new App::Cmd object. During initialization, command plugins will be loaded.

Valid arguments are:

  no_commands_plugin - if true, the command list plugin is not added

  no_help_plugin     - if true, the help plugin is not added

  no_version_plugin  - if true, the version plugin is not added

  show_version_cmd -   if true, the version command will be shown in the
                       command list

  plugin_search_path - The path to search for commands in. Defaults to
                       results of plugin_search_path method

If "no_commands_plugin" is not given, App::Cmd::Command::commands will be required, and it will be registered to handle all of its command names not handled by other plugins.

If "no_help_plugin" is not given, App::Cmd::Command::help will be required, and it will be registered to handle all of its command names not handled by other plugins. Note: "help" is the default command, so if you do not load the default help plugin, you should provide your own or override the "default_command" method.

If "no_version_plugin" is not given, App::Cmd::Command::version will be required to show the application's version with command "--version". By default, the version command is not included in the command list. Pass "show_version_cmd" to include the version command in the list.

  run
  $cmd->run;

This method runs the application. If called the class, it will instantiate a new App::Cmd object to run.

It determines the requested command (generally by consuming the first command-line argument), finds the plugin to handle that command, parses the remaining arguments according to that plugin's rules, and runs the plugin.

It passes the contents of the global argument array (@ARGV) to ""prepare_command"", but @ARGV is not altered by running an App::Cmd.

  prepare_args
Normally App::Cmd uses @ARGV for its commandline arguments. You can override this method to change that behavior for testing or otherwise.

  default_args
If "prepare_args" is not changed and there are no arguments in @ARGV, this method is called and should return an arrayref to be used as the arguments to the program. By default, it returns an empty arrayref.

  abstract
   sub abstract { "command description" }

Defines the command abstract: a short description that will be printed in the main command options list.

  description
   sub description { "Long description" }

Defines a longer command description that will be shown when the user asks for help on a specific command.

  arg0

  full_arg0
  my $program_name = $app->arg0;

  my $full_program_name = $app->full_arg0;

These methods return the name of the program invoked to run this application. This is determined by inspecting $0 when the App::Cmd object is instantiated, so it's probably correct, but doing weird things with App::Cmd could lead to weird values from these methods.

If the program was run like this:

  knight!rjbs$ ~/bin/rpg dice 3d6

Then the methods return:

  arg0      - rpg
  full_arg0 - /Users/rjbs/bin/rpg

These values are captured when the App::Cmd object is created, so it is safe to assign to $0 later.

  prepare_command
  my ($cmd, $opt, @args) = $app->prepare_command(@ARGV);

This method will load the plugin for the requested command, use its options to parse the command line arguments, and eventually return everything necessary to actually execute the command.

  default_command
This method returns the name of the command to run if none is given on the command line. The default default is "help"

  execute_command
  $app->execute_command($cmd, \%opt, @args);

This method will invoke "validate_args" and then "run" on $cmd.

  plugin_search_path
This method returns the plugin_search_path as set. The default implementation, if called on "YourApp::Cmd" will return "YourApp::Cmd::Command"

This is a method because it's fun to override it with, for example:

  use constant plugin_search_path => __PACKAGE__;

  allow_any_unambiguous_abbrev
If this method returns true (which, by default, it does not), then any unambiguous abbreviation for a registered command name will be allowed as a means to use that command. For example, given the following commands:

  reticulate
  reload
  rasterize

Then the user could use "ret" for "reticulate" or "ra" for "rasterize" and so on.

  global_options
  if ($cmd->app->global_options->{verbose}) { ... }

This method returns the running application's global options as a hashref. If there are no options specified, an empty hashref is returned.

  set_global_options
  $app->set_global_options(\%opt);

This method sets the global options.

  command_names
  my @names = $cmd->command_names;

This returns the commands names which the App::Cmd object will handle.

  command_groups
  my @groups = $cmd->commands_groups;

This method can be implemented to return a grouped list of command names with optional headers. Each group is given as arrayref and each header as string. If an empty list is returned, the commands plugin will show two groups without headers: the first group is for the "help" and "commands" commands, and all other commands are in the second group.

  command_plugins
  my @plugins = $cmd->command_plugins;

This method returns the package names of the plugins that implement the App::Cmd object's commands.

  plugin_for
  my $plugin = $cmd->plugin_for($command);

This method returns the plugin (module) for the given command. If no plugin implements the command, it returns false.

  get_command
  my ($command_name, $opt, @args) = $app->get_command(@args);

Process arguments and into a command name and (optional) global options.

  usage
  print $self->app->usage->text;

Returns the usage object for the global options.

  usage_desc
The top level usage line. Looks something like

  "yourapp <command> [options]"

  global_opt_spec
Returns a list with help command unless "no_help_plugin" has been specified or an empty list. Can be overridden for pre-dispatch option processing. This is useful for flags like --verbose.

  usage_error
  $self->usage_error("Something's wrong!");

Used to die with nice usage output, during "validate_args".

TODO

•   publish and bring in Log::Speak (simple quiet/verbose output)

•   publish and use our internal enhanced describe_options

•   publish and use our improved simple input routines

AUTHOR
Ricardo Signes <cpan@semiotic.systems>

CONTRIBUTORS

•   Adam Prime <aprime@oanda.com>

•   ambs <ambs@cpan.org>

•   Andreas Hernitscheck <andreash@lxhe.(none)>

•   A. Sinan Unur <nanis@cpan.org>

•   Chris 'BinGOs' Williams <chris@bingosnet.co.uk>

•   David Golden <dagolden@cpan.org>

•   David Steinbrunner <dsteinbrunner@pobox.com>

•   Davor Cubranic <cubranic@stat.ubc.ca>

•   Denis Ibaev <dionys@gmail.com>

•   Diab Jerius <djerius@cfa.harvard.edu>

•   Glenn Fowler <cebjyre@cpan.org>

•   Ingy dot Net <ingy@ingy.net>

•   Jakob Voss <voss@gbv.de>

•   Jérôme Quelin <jquelin@gmail.com>

•   John SJ Anderson <genehack@genehack.org>

•   Karen Etheridge <ether@cpan.org>

•   Kent Fredric <kentfredric@gmail.com>

•   Lucas Theisen <ltheisen@mitre.org>

•   Matthew Astley <mca@sanger.ac.uk>

•   Michael McClimon <michael@mcclimon.org>

•   mokko <mauricemengel@gmail.com>

•   Olivier Mengué <dolmen@cpan.org>

•   Ricardo Signes <rjbs@semiotic.systems>

•   Ryan C. Thompson <rct@thompsonclan.org>

•   Salvatore Bonaccorso <carnil@debian.org>

•   Sawyer X <xsawyerx@cpan.org>

•   Sergey Romanov <sromanov-dev@yandex.ru>

•   Stephan Loyd <stephanloyd9@gmail.com>

•   Stephen Caldwell <steve@campusexplorer.com>

•   Yuval Kogman <nuffin@cpan.org>

COPYRIGHT AND LICENSE
This software is copyright (c) 2026 by Ricardo Signes.

This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.