Provided by: libterm-shell-perl_0.02-3_all bug


       Term::Shell - A simple command-line shell framework.


           package MyShell;
           use base qw(Term::Shell);

           sub run_command1  { print "command 1!\n"; }
           sub smry_command1 { "what does command1 do?" }
           sub help_command1 {
           Help on 'command1', whatever that may be...

           sub run_command2 { print "command 2!\n"; }

           package main;
           my $shell = MyShell->new;


       Term::Shell lets you write simple command-line shells. All the boring details like
       command-line parsing, terminal handling, and tab completion are handled for you.

       The base class comes with two commands pre-defined: exit and help.

       To write a shell with an "exec" command, do something like this:

          package MyShell;
          use base qw(Term::Shell); # or manually edit @MyShell::ISA.

          sub run_exec {
              my ($o, $cmd, @args) = @_;
              if ($cmd ne $0) {
                  print "I'm sorry you're leaving us...\n";
              exec $cmd, @args;
              exit 1;

       When Term::Shell needs to handle the "exec" command, it will invoke this method. That's
       all there is to it! You write handlers, and Term::Shell handles the gory details.

Using Term::Shell Shells

       How do you bring your shell to life? Assuming the package "MyShell" contains your actions,
       just do this:

          use MyShell;
          my $shell = MyShell->new;

          # Setup code here (if you wish)

          # Invoke the shell

          # Cleanup code here (if you wish)

       Most people put the setup code in the shell itself, so you can usually get away with this:

          use MyShell;

       It's that simple! All the actions and command handlers go in "", and your main
       program is simple. In fact, it's so simple that some people like to write both the actions
       and the invocation in the same file:

          package main;

          package MyShell;
          use base qw(Term::Shell);

          # Actions here

       Adding commands to your shell is just as easy, if not easier.

Adding Commands to Your Shell

       For every command "foo", Term::Shell needs a method called "run_foo()", where 'foo' is
       what the user will type in. The method will be called with the Term::Shell object as the
       first parameter, followed by any arguments the user typed after the command.

       Several prefixes other than "run_" are supported; each prefix tells Term::Shell to call
       that handler under different circumstances. The following list enumerates all the
       "special" prefixes. Term::Shell will ignore any method that doesn't start with a prefix
       listed here.

       1.  run_foo()

           Adds the command "foo" to the list of supported commands. The method's return value is
           saved by Term::Shell, but is not used.

           The method is called with the Term::Shell object as its first argument, followed by
           any arguments the user typed in.

           Special case: if you provide a method "run_()", Term::Shell will call it whenever the
           user enters a blank line. A blank line is anything which matches the regular
           expression "/^\s*$/".

       2.  help_foo()

           Adds the command "foo" to the list of help topics. This means the user may enter 'help
           foo' and get a help screen. It should return a single string to be displayed to the

           The method is called with the Term::Shell object as its first argument, followed by
           any arguments the user typed in after 'help foo'. You can implement hierarchical help
           documents by using the arguments.

           If you do not provide a "help_foo()" method, typing 'help foo' produces an error

       3.  smry_foo()

           Should return a one-line summary of "foo", to be displayed in the help screen.

           This method is called with the Term::Shell object as its first argument, and no other

           If you do not provide a "smry_foo()" method, then the string 'undocumented' is used

       4.  comp_foo()

           Provides custom tab-completion for "foo". That means if the user types 'foo ' and then
           hits <TAB>, this method will be called. It should return an array reference containing
           a list of possible completions.

           This method is called with the Term::Shell object as its first argument, followed by
           the three arguments:

           1.  $word

               The word the user is trying to complete.

           2.  $line

               The line as typed by the user so far.

           3.  $start

               The offset into $line where $word starts.

           If you do not provide "comp_foo()", Term::Shell will always return no completions for

           Special case: if you provide "comp_()", Term::Shell will call it when the user is
           trying to complete the name of a command. Term::Shell provides a default "comp_()"
           method, which completes the actions that you have written handlers for. If you want to
           provide tab-completion for commands that do not have handlers, override "comp_()".

       5.  alias_foo()

           Returns a list of aliases for "foo". When one of the aliases is used instead of "foo",
           the corresponding handler for "foo" is called.

       6.  catch_run()




           Called when an undefined action is entered by the user. Normally when the user enters
           an unrecognized command, Term::Shell will print an error message and continue.

           This method is called with the Term::Shell object, the command typed by the user, and
           then the arguments which would normally be passed to the real handler.

           The "catch_" methods may do anything the original function would have done.  If you
           want, you can implement all the commands in it, but that means you're doing more work
           than you have to. Be lazy.

   When you want something done right...
       You sometimes have to do it yourself. Introducing add_handlers(). Naturally, it adds a
       handler to the list of defined handlers in the shell.

       Term::Shell can't always find the commands you want to implement by searching the
       inheritance tree. Having an AUTOLOAD() method, for instance, will break this system. In
       that situation, you may wish to tell Term::Shell about the extra commands available using

          package MyShell;
          use base qw(Term::Shell);

          sub AUTOLOAD {
              if ($AUTOLOAD =~ /::run_fuzz$/) {
                  # code for 'fuzz' command
              elsif ($AUTOLOAD =~ /::run_foozle$/) {
                  # code for 'foozle' command

          sub init {
              my $o = shift;
              $o->add_handlers("run_fuzz", "run_foozle");

       There are other ways to do this. You could write a "catch_run" routine and do the same
       thing from there. You'd have to override "comp_" so that it would complete on "foozle" and
       "fuzz". The advantage to this method is that it adds the methods to the list of commands,
       so they show up in the help menu and you get completion for free.

Removing Commands from Your Shell

       You're probably thinking "just don't write them". But remember, you can inherit from
       another shell class, and that parent may define commands you want to disable. Term::Shell
       provides a simple method to make itself forget about commands it already knows about:

       1.  remove_commands()

           Removes all handlers associated with the given command (or list of commands).

           For example, Term::Shell comes with two commands ("exit" and "help") implemented with
           seven handlers:

           1.  smry_exit()

           2.  help_exit()

           3.  run_exit()

           4.  smry_help()

           5.  help_help()

           6.  comp_help()

           7.  run_help()

           If you want to create a shell that doesn't implement the "help" command, your code
           might look something like this example:

              package MyShell;
              use base qw(Term::Shell);

              sub init {
                  my $o = shift;

              # ... define more handlers here ...

       2.  remove_handlers()

           Removes the given handler (or handlers) from the list of defined commands. You have to
           specify a full handler name, including the 'run_' prefix. You can obviously specify
           any of the other prefixes too.

           If you wanted to remove the help for the "exit" command, but preserve the command
           itself, your code might look something like this:

              package MyShell;
              use base qw(Term::Shell);

              sub init {
                  my $o = shift;

              # ... define more handlers here ...

   Cover Your Tracks
       If you do remove built in commands, you should be careful not to let Term::Shell print
       references to them. Messages like this are guaranteed to confuse people who use your

          shell> help
          Unknown command 'help'; type 'help' for a list of commands.

       Here's the innocuous looking code:

          package MyShell;
          use base qw(Term::Shell);

          sub init {
              my $o = shift;


       The problem is that Term::Shell has to print an error message, and by default it tells the
       user to use the "help" command to see what's available. If you remove the "help" command,
       you still have to clean up after yourself and tell Term::Shell to change its error

       1.  msg_unknown_cmd()

           Called when the user has entered an unrecognized command, and no action was available
           to satisfy it. It receives the object and the command typed by the user as its
           arguments. It should return an error message; by default, it is defined thusly:

              sub msg_unknown_cmd {
                  my ($o, $cmd) = @_;
              Unknown command '$cmd'; type 'help' for a list of commands.

       2.  msg_ambiguous_cmd()

           Called when the user has entered a command for which more than handler exists.  (For
           example, if both "quit" and "query" are commands, then "qu" is an ambiguous command,
           because it could be either.) It receives the object, the command, and the possible
           commands which could complete it. It should return an error message; by default it is
           defined thusly:

              sub msg_ambiguous_cmd {
                  my ($o, $cmd, @c) = @_;
                  local $" = "\n\t";
              Ambiguous command '$cmd': possible commands:

The Term::Shell API

       Shell classes can use any of the methods in this list. Any other methods in Term::Shell
       may change.

       1.  new()

           Creates a new Term::Shell object. It currently does not use its arguments. The
           arguments are saved in '$o->{API}{args}', in case you want to use them later.

              my $sh = Term::Shell->new(@arbitrary_args);

       2.  cmd()


           Invokes $txt as if it had been typed in at the prompt.

              $sh->cmd("echo 1 2 3");

       3.  cmdloop()


           Repeatedly prompts the user, reads a line, parses it, and invokes a handler.  Uses
           "cmd()" internally.


           mainloop() is a synonym for cmdloop(), provided for backwards compatibility.  Earlier
           (unreleased) versions of Term::Shell have only provided mainloop().  All documentation
           and examples use cmdloop() instead.

       4.  init()


           Do any initialization or cleanup you need at shell creation (init()) and destruction
           (fini()) by defining these methods.

           No parameters are passed.

       5.  preloop()


           Do any initialization or cleanup you need at shell startup (preloop()) and shutdown
           (postloop()) by defining these methods.

           No parameters are passed.

       6.  precmd()


           Do any initialization or cleanup before and after calling each handler.

           The parameters are:

           1.  $handler

               A reference to the name of the handler that is about to be executed.

               Passed by reference so you can control which handler will be called.

           2.  $cmd

               A reference to the command as the user typed it.

               Passed by reference so you can set the command. (If the handler is a "catch_"
               command, it can be fooled into thinking the user typed some other command, for

           3.  $args

               The arguments as typed by the user. This is passed as an array reference so that
               you can manipulate the arguments received by the handler.

              sub precmd {
                  my $o = shift;
                  my ($handler, $cmd, @args) = @_;
                  # ...

       7.  stoploop()

           Sets a flag in the Term::Shell object that breaks out of cmdloop(). Note that
           cmdloop() resets this flag each time you call it, so code like this will work:

              my $sh = MyShell->new;
              $sh->cmdloop;        # an interactive session
              $sh->cmdloop;        # prompts the user again

           Term::Shell's built-in run_exit() command just calls stoploop().

       8.  idle()

           If you set "check_idle" to a non-zero number (see "The Term::Shell Object") then this
           method is called every "check_idle" seconds. The idle() method defined in Term::Shell
           does nothing -- it exists only to be redefined in subclasses.

              package MyShell;
              use base qw(Term::Shell);

              sub init {
                  my $o = shift;
                  $o->{API}{check_idle} = 0.1;     # 10/s

              sub idle {
                  print "Idle!\n";

       9.  prompt_str()

           Returns a string to be used as the prompt. prompt_str() is called just before calling
           the readline() method of Term::ReadLine. If you do not override this method, the
           string `shell> ' is used.

              package MyShell;
              use base qw(Term::Shell);

              sub prompt_str { "search> " }

       10. prompt()

           Term::Shell provides this method for convenience. It's common for a handler to ask the
           user for more information. This method makes it easy to provide the user with a
           different prompt and custom completions provided by you.

           The prompt() method takes the following parameters:

           1.  $prompt

               The prompt to display to the user. This can be any string you want.

           2.  $default

               The default value to provide. If the user enters a blank line (all whitespace
               characters) then the this value will be returned.

               Note: unlike ExtUtils::MakeMaker's prompt(), Term::Shell's prompt() does not
               modify $prompt to indicate the $default response. You have to do that yourself.

           3.  $completions

               An optional list of completion values. When the user hits <TAB>, Term::Shell
               prints the completions which match what they've typed so far. Term::Shell does not
               enforce that the user's response is one of these values.

           4.  $casei

               An optional boolean value which indicates whether the completions should be
               matched case-insensitively or not. A true value indicates that "FoO" and "foo"
               should be considered the same.

           prompt() returns the unparsed line to give you maximum flexibility. If you need the
           line parsed, use the line_parsed() method on the return value.

       11. cmd_prefix()


           These methods should return a prefix and suffix for commands, respectively.  For
           instance, an IRC client will have a prefix of "/". Most shells have an empty prefix
           and suffix.

       12. page()


           Prints $txt through a pager, prompting the user to press a key for the next screen
           full of text.

       13. line()


           Although "run_foo()" is called with the parsed arguments from the command-line, you
           may wish to see the raw command-line. This is available through the line() method. If
           you want to retrieve the parsed line again, use line_parsed().

           line_parsed() accepts an optional string parameter: the line to parse. If you have
           your own line to parse, you can pass it to line_parsed() and get back a list of
           arguments. This is useful inside completion methods, since you don't get a parsed list

       14. run()

           If you want to run another handler from within a handler, and you have pre-parsed
           arguments, use run() instead of cmd(). cmd() parses its parameter, whereas run() takes
           each element as a separate parameter.

           It needs the name of the action to run and any arguments to pass to the handler.

           Term::Shell uses this method internally to invoke command handlers.

       15. help()

           If you want to get the raw text of a help message, use help(). It needs the name of
           the help topic and any arguments to pass to the handler.

           Term::Shell uses this method internally to invoke help handlers.

       16. summary()

           If you want to get the summary text of an action, use summary(). It needs the name of
           the action.

           Term::Shell uses this method internally to display the help page.

       17. possible_actions()

           You will probably want this method in comp_foo(). possible_actions() takes a word and
           a list, and returns a list of possible matches. Term::Shell uses this method
           internally to decide which handler to run when the user enters a command.

           There are several arguments, but you probably won't use them all in the simple cases:

           1.  $needle

               The (possible incomplete) word to try to match against the list of actions (the

           2.  $type

               The type with which to prefix $action. This is useful when completing a real
               action -- you have to specify whether you want it to look for "run_" or "help_" or
               something else. If you leave it blank, it will use $action without prefixing it.

           3.  $strip

               If you pass in a true value here, possible_actions() will remove an initial $type
               from the beginning of each result before returning the results. This is useful if
               you want to know what the possible "run_" commands are, but you don't want to have
               the "run_" in the final result.

               If you do not specify this argument, it uses '0' (the default is not to strip the

           4.  $haystack

               You can pass in a reference to a list of strings here. Each string will be
               compared with $needle.

               If you do not specify this argument, it uses the list of handlers. This is how
               Term::Shell matches commands typed in by the user with command handlers written by

       18. print_pairs()

           This overloaded beast is used whenever Term::Shell wants to print a set of keys and
           values. It handles wrapping long values, indenting the whole thing, inserting the
           separator between the key and value, and all the rest.

           There are lots of parameters, but most of them are optional:

           1.  $keys

               A reference to a list of keys to print.

           2.  $values

               A reference to a list of values to print.

           3.  $sep

               The string used to separate the keys and values. If omitted, ': ' is used.

           4.  $left

               The justification to be used to line up the keys. If true, the keys will be left-
               justified. If false or omitted, the keys will be right-justified.

           5.  $ind

               A string used to indent the whole paragraph. Internally, print_pairs() uses
               length(), so you shouldn't use tabs in the indent string. If omitted, the empty
               string is used (no indent).

           6.  $len

               An integer which describes the minimum length of the keys. Normally, print_pairs()
               calculates the longest key and assigns the column width to be as wide as the
               longest key plus the separator. You can force the column width to be larger using
               $len. If omitted, 0 is used.

           7.  $wrap

               A boolean which indicates whether the value should be text-wrapped using
               Text::Autoformat. Text is only ever wrapped if it contains at least one space.  If
               omitted, 0 is used.

           8.  $cols

               An integer describing the number of columns available on the current terminal.
               Normally 78 is used, or the environment variable COLUMNS, but you can override the
               number here to simulate a right-indent.

       19. term()

           Returns the underlying "Term::ReadLine" object used to interact with the user. You can
           do powerful things with this object; in particular, you will cripple Term::Shell's
           completion scheme if you change the completion callback function.

       20. process_esc()

           This method may be overridden to provide shell-like escaping of backslashes inside
           quoted strings. It accepts two parameters:

           1.  $c

               The character which was escaped by a backslash.

           2.  $quote

               The quote character used to delimit this string. Either """ or "'".

           This method should return the string which should replace the backslash and the
           escaped character.

           By default, process_esc() uses escaping rules similar to Perl's single-quoted string:

           1.  Escaped backslashes return backslashes. The string "123\\456" returns "123\456".

           2.  Escaped quote characters return the quote character (to allow quote characters in
               strings). The string "abc\"def" returns "abc"def".

           3.  All other backslashes are returned verbatim. The string "123\456" returns

           Term::Shell's quote characters cannot be overridden, unless you override
           line_parsed(): they are """ or "'". This may change in a future version of

       21. add_handlers()

           See "Adding Commands to Your Shell" for information on add_handlers().

       22. remove_commands()


           See "Removing Commands from Your Shell" for information on remove_handlers().

The Term::Shell Object

       Term::Shell creates a hash based Perl object. The object contains information like what
       handlers it found, the underlying Term::ReadLine object, and any arguments passed to the

       This hash is broken into several subhashes. The only two subhashes that a Shell should
       ever use are $o->{API} and $o->{SHELL}. The first one contains all the information that
       Term::Shell has gathered for you. The second one is a private area where your Shell can
       freely store data that it might need later on.

       This section will describe all the Term::Shell object "API" attributes:

   The args Attribute
       This an array reference containing any arguments passed to the Term::Shell constructor.

   The case_ignore Attribute
       This boolean controls whether commands should be matched without regard to case. If this
       is true, then typing "FoO" will have the same effect as typing "foo".

       Defaults to true on MSWin32, and false on other platforms.

   The class Attribute
       The class of the object. This is probably the package containing the definition of your
       shell, but if someone subclasses your shell, it's their class.

   The command Attribute
       Whenever Term::Shell invokes an action, it stores information about the action in the
       "command" attribute. Information about the last "run" action to be invoked is stored in
       $o->{API}{command}{run}. The information itself is stored in a subhash containing these

           The name of the command, as typed by the user.

           The a boolean value indicating whether a handler could be found.

           The full name of the handler, if found.

       Note that this facility only stores information about the last action to be executed. It's
       good enough for retrieving the information about the last handler which ran, but not for
       much else.

       The following example shows a case where "run_foo()" calls "run_add()", and prints its
       return value (in this case, 42).

          sub run_foo {
              my $o = shift;
              my $sum = $o->run("add", 21, 21);
              print "21 + 21 = ", $sum, "\n";

          sub run_add {
              my $o = shift;
              my $sum = 0;
              $sum += $_ for @_;
              print "add(): sum = $sum\n";
              return $sum;

       At the end of run_foo(), $o->{API}{command}{run}{handler} contains the string "run_add".

   The match_uniq Attribute
       This boolean controls whether the user can type in only enough of the command to make it
       unambiguous. If true, then if the shell has the commands "foo" and "bar" defined, the user
       can type "f" to run "foo", and "b" to run "bar".

       Defaults to true.

   The readline Attribute
       Which Term::ReadLine module is being used. Currently, this is always one of
       "Term::ReadLine::Stub", "Term::ReadLine::Perl", or "Term::ReadLine::Gnu".

   The script Attribute
       The name of the script that invoked your shell.

   The version Attribute
       The version of Term::Shell you are running under.


       There are bound to be some bugs lurking about.

       If you find bugs, please send them to "".


       For more information about the underlying ReadLine module, see Term::ReadLine. You may
       also want to look at Term::ReadLine::Gnu and Term::ReadLine::Perl.

       For more information about the underlying formatter used by print_pairs(), see

       The API for Term::Shell was inspired by (gasp!) a Python package called "cmd". For more
       information about this package, please look in the Python Library Reference, either in
       your Python distribution or at


       Neil Watkiss (


       Copyright (c) 2001, Neil Watkiss. All Rights Reserved.

       All Rights Reserved. This module is free software. It may be used, redistributed and/or
       modified under the same terms as Perl itself.



       Hey! The above document had some coding errors, which are explained below:

       Around line 211:
           You forgot a '=back' before '=head2'

       Around line 244:
           =back without =over