Term::Shell::MultiCmd - Nested Commands Tree in Shell Interface


    # Examples are available with the distribution, under directory 'examples/'
    # This one is named examples/

    use Term::Shell::MultiCmd;
    my @command_tree =
     ( 'multi word command' =>
             { help => "Help title.",
               opts => 'force repeat=i',
               exec => sub {
                   my ($o, %p) = @_ ;
                   print "$p{ARG0} was called with force=$p{force} and repeat=$p{repeat}\n"
       'multi word another command' =>
             { help => 'Another help title.
  Help my have multi lines, the top one
  would be used when one linear needed.',
               comp => sub {
                   # this function would be called when use hits tab completion at arguments
                   my ($o, $word, $line, $start, $op, $opts) = @_ ;
                   # .. do something, then
                   return qw/a list of completion words/ ;
               exec => sub { my ($o, %p) = @_ ; print "$p{ARG0} was called\n"},
       'multi word third command' =>
             { help => 'same idea',
               comp => [qw/a list of words/], # this is also possible
               exec => sub { my ($o, %p) = @_ ; print "$p{ARG0} was called. Isn't that fun?\n"},
       'multi word' => 'You can add general help title to a path',
     ) ;

      -> new()
      -> populate( @command_tree )
      -> loop ;

    print "All done, see you later\n" ;


To get the most from a command line, it might be a good idea to get the latest versions of Term::ReadLine and Term::ReadKey. There are numberless ways of doing it, one of them is running 'cpan update Bundle::CPAN' (with a proper write permission).

If you use MacOS, and the completion tab converts newlines to literal '\n' chars, you can try using Term::ReadLine::Perl5 instead of Term::ReadLine::Gnu. One way of doing it is with the code below: BEGIN{ $ENV{PERL_RL} = "Perl o=0" }



    my $cli = new Term::Shell::MultiCmd ;
   - or -
    my $cli = Term::Shell::MultiCmd->new( [optional parameters ...] ) ;

The parameters to the constructor are passed in hash form, preceding dash is optional.

Optional Parameters for the new command:

  • -prompt

        my $cli = new Term::Shell::MultiCmd ( -prompt => 'myprompt') ;
    - or -
        my $cli = mew Term::Shell::MultiCmd ( -prompt => \&myprompt) ;

    Overwrite the default prompt 'shell'. Rules are:

     If prompt is a CODE reference, call it in each loop cycle and display the results.
     if it ends with a non-word character, display it as is.
     Else, display it with the root-path (if exists) and '> ' characters.
  • -help_cmd

    Overwrite the default 'help' command, empty string would disable this command.

  • -quit_cmd

    Overwrite the default 'quit' command, empty string would disable this command.

  • -root_cmd

        my $cli = new Term::Shell::MultiCmd ( -root_cmd => 'root' ) ;

    This would enable the root command and set it to root.

    Unlike 'quit' and 'help', the 'root' command is a little unexpected. Therefore it is disabled by default. I strongly recommend enabling this command when implementing a big, deep command tree. This allows the user rooting in a node, then referring to this node thereafter. After enabling, use 'help root' (or whatever names you've chosen) for usage manual.

  • -history_file

        my $cli = new Term::Shell::MultiCmd ( -history_file => "$ENV{HOME}/.my_progarms_data" ) ;

    This is the history file name. If present, try to load history from this file just before the loop command, and try saving history in this file after the loop command. Default is an empty string (i.e. no history preserved between sessions). Please note that things might get tricky if that if multiple sessions are running at the same time.

  • -history_size

    Overwrite the default 100 history entries to save in hisotry_file (if exists).

  • -history_more

    If the history_file exists, try to load this data from the file during initialization, and save it at loop end. For Example:

       my %user_defaults ;
       my $cli = new Term::Shell::MultiCmd ( -history_file => "$ENV{HOME}/.my_saved_data",
                                             -history_size => 200,
                                             -history_more => \%user_defaults,
                                            ) ;
       # ....
       $cli -> loop ;

    This would load shell's history and %user_defaults from the file .my_saved_data before the loop, and store 200 history entries and %user_defaults in the file after the loop.

    Note that the value of history_more must be a reference for HASH, ARRAY, or SCALAR. And no warnings would be provided if any of the operations fail. It wouldn't be a good idea to use it for sensitive data.

  • -history_flash_file

    This is a newer feature, somehow replacing -history_file: If -history_flash_file exists, then use it for commands history - but write each command to the EOF immediatly after execution. This is helpful in two cases - when using multiple sessions and when the process exits ungracefully. Note that in this case, -history_file will be used as a container for -history_more only. Example:

       my %config ;
       my $cli = new Term::Shell::MultiCmd ( -history_file => "$ENV{HOME}/.my_saved_config",       # keep \%config only
                                             -history_size => 200,
                                             -history_more => \%config,
                                             -history_flash_file => "$ENV{HOME}/.my_saved_hisotry" # keep all history
                                             ) ;
  • -pager

    As pager's value, this module would expect a string or a sub that returns a FileHandle. If the value is a string, it would be converted to:

       sub { use FileHandle ; new FileHandle "| $value_of_pager" }

    When appropriate, the returned file handle would be selected before user's command execution, the old one would be restored afterward. The next example should work on most posix system:

       my $cli = new Term::Shell::MultiCmd ( -pager => 'less -rX',

    The default pager's value is empty string, which means no pager manipulations.

  • -pager_re

    Taking after perldb, the default value is '^\|' (i.e. a regular expression that matches '|' prefix, as in the user's command "| help"). If the value is set to an empty string, every command would trigger the pager.

    The next example would print any output to a given filehandle:

       my $ret_value ;
       my $cli = new Term::Shell::MultiCmd ( -pager => sub {
                                                   open my $fh, '>', \$ret_value or die "can't open FileHandle to string (no PerlIO?)\n" ;
                                             -pager_re => '',
                                           ) ;
      # ...
      $cli -> cmd ('help -t') ;
      print "ret_value is:\n $ret_value" ;
  • -record_cmd

    If it's a function ref, call it with an echo of the user's command

       my $cli = new Term::Shell::MultiCmd ( -record_cmd => sub {
                                                my $user_cmd = shift;
                                                system "echo '$user_cmd' >> /tmp/history"
                                           ) ;
  • -empty_cmd

    Function ref only, call it when user hits 'Return' with no command or args (not even spaces)

       my $cli = new Term::Shell::MultiCmd ( -empty_cmd => sub {
                                                    # Assuming some commands are recorded in $last_repeatable_cmd
                                                    if ( $last_repeatable_cmd ) {
                                                        # repeat it
                                           ) ;
  • -query_cmd

    If exeuting a node, and node contains the query cmd, it would be executed instead of the help command (on the node) Default: 'query' For exmaple, with this feature, if "my cmd query" exists, it would also be exeuted at "my cmd'

       my $cli = new Term::Shell::MultiCmd ( -query_cmd => 'query',
                                           ) ;
    =item * -enable_sh_pipe

    If true, allow redirect output to a shell command by the suffix ' | <chell cmd>'. Example: Shell> my multy path cmd | grep -w 42 Default is value is 1, To disable, set it to false (0 or '' or undef)

       my $cli = new Term::Shell::MultiCmd ( -enable_sh_pipe => '',
                                           ) ;

    Note: If both pager and this pipe are used, the pipe will be ingored and the command will get whole line as argument.


   $cli -> add_exec ( -path => 'full command path',
                      -exec => \&my_command,
                      -help => 'some help',
                      -opts => 'options',
                      -comp => \&my_completion_function,
                    ) ;

This function adds an command item to the command tree. It is a little complicated, but useful (or so I hope).

  • -path

    Mandatory. Expecting a string. This string would be parsed as multi-words command.

    Note: by default, this module expects whitespaces delimiter. If you'll read the module's code, you can find an easy way to change it - in unlikely case you'll find it useful.

  • -exec

    Mandatory. Expecting a function ref. This code would be called when the user types a unique path for this command (with optional options and arguments). Parameters sent to this code are:

       my ($cli, %p) = @_ ;
       #  where:
       # $cli     - self object.
       # $p{ARG0} - the command's full path (user might have used partial but unique path. This is the explicit path)
       # $p{ARGV} - all user arguments, in order (ARRAY ref)
       # %p       - contains other options (see 'opts' below)
  • -help

    Expecting a multi line string. The top line would be presented when a one line title is needed (for example, when 'help -tree' is called), the whole string would be presented as the full help for this item.

  • -comp

    Expecting CODE, or ARRAY ref, or HASH ref. If Array, when the user hits tab completion for this command, try to complete his input with words from this list. If Hash, using the hash keys as array, following the rule above. If Code, call this function with the next parameters:

       my ($cli, $word, $line, $start) = @_ ;
       #  where:
       # $cli is the Term::Shell::MultiCmd object.
       # $word is the curent word
       # $line is the whole line
       # $start is the current location

    This code should return a list of strings. Term::ReadLine would complete user's line to the longest common part, and display the list (unless unique). In other words - it would do what you expect.

    For more information, see Term::ReadLine.

  • -opts

    Expecting a string, or ARRAY ref. If a string, split it to words by whitespaces. Those words are parsed as standard Getopt::Long options. For example:

         -opts => 'force name=s flag=i@'

    This would populating the previously described %p hash, correspond to user command:

         shell> user command -name="Some String" -flag 2 -flag 3 -flag 4 -force

    For more information, see Getopt::Long. Also see examples/ in distribution.

    As ARRAY ref, caller can also add a complete 'instruction' after each non-flag option (i.e. an option that expects parameters). Like the 'comp' above, this 'instruction' must be an ARRAY or CODE ref, and follow the same roles. When omitted, a default function would be called and ask the user for input. For example:

        -opts => [ 'verbose' =>
                   'file=s'  => \&my_filename_completion,
                   'level=i' => [qw/1 2 3 4/],
                   'type=s'  => \%my_hash_of_types,


Although help string can set in add_exec, this command is useful when he wishes to add title (or hint) to a part of the command path. For example:

   # assume $cli with commands 'feature set', 'feature get', etc.
   $cli -> add_help ( -path => 'feature' ,
                      -help => 'This feature is about something') ;


A convenient way to define a chain of add_exec and add_help commands. This function expects hash, where the key is the command path and the value might be HASH ref (calling add_exec), or a string (calling add_help). For example:

    $cli -> populate
       ( 'feature' => 'This feature is a secret',
         'feature set' => { help => 'help for feature set',
                            exec => \&my_feature_set,
                            opts => 'level=i',
                            comp => \&my_feature_set_completion_function,
         'feature get' => { help => 'help for feature get',
                            exec => \&my_feature_get
       ) ;

    # Note:
    # - Since the key is the path, '-path' is omitted from parameters.
    # - This function returns the self object, for easy chaining (as the synopsis demonstrates).


  $cli -> loop ;

Prompt, parse, and invoke in an endless loop

('endless loop' should never be taken literally. Users quit, systems crash, universes collapse - and the loop reaches its last cycle)


 $cli -> cmd ( "help -tree" ) ;

Execute the given string parameter, similarly to user input. This one might be useful to execute commands in a script, or testing.


 $cli -> command ( "help -tree") ;
Is the same as cmd, but echos the command before execution


  my ($base_line, @word_list) = $cli -> complete ($a_line) ;

given a line, this function would return a base line (i.e. truncated to the beginning of the last word), and a list of potential completions. Added to the 'cmd' command, this might be useful when module user implements his own 'loop' command in a non-terminal application


  my $prompt = $cli -> prompt() ;

accepts no parameters, return current prompt.


set/get history

  my @hist = $cli -> history() ;            # get history
  $cli -> history( @alternative_history ) ; # set history
  $cli -> history([@alternative_history]) ; # the very same, by ptr
  $cli -> history([]) ;                     # clear history


Term::ReadLine, Term::ReadKey, Getopt::Long


Josef Ezra, <jezra at sign>


Please report any bugs or feature requests to me, or to bug-term-cli at, or through the web interface at I am grateful for your feedback.

TODO list

nImplement pager.


You can find documentation for this module with the perldoc command.

    perldoc Term::Shell::MultiCmd

You can also look for information at:


This module was inspired by the excellent modules Term::Shell, CPAN, and CPANPLUS::Shell.


Copyright 2010 Josef Ezra.

This program is free software; you can redistribute it and/or modify it under the terms of either: the GNU General Public License as published by the Free Software Foundation; or the Artistic License.

See for more information.