1Term::Shell(3) User Contributed Perl Documentation Term::Shell(3)
2
6 Term::Shell - A simple command-line shell framework.
7
9 version 0.12
10
12 package MyShell;
13 use base qw(Term::Shell);
14 sub run_command1 { print "command 1!\n"; }
16 sub smry_command1 { "what does command1 do?" }
17 sub help_command1 {
18 <<'END';
19 Help on 'command1', whatever that may be...
20 END
21 }
22 sub run_command2 { print "command 2!\n"; }
24 package main;
26 my $shell = MyShell->new;
27 $shell->cmdloop;
28
30 Term::Shell lets you write simple command-line shells. All the boring
31 details like command-line parsing, terminal handling, and tab
32 completion are handled for you.
33 The base class comes with two commands pre-defined: exit and help.
35 To write a shell with an "exec" command, do something like this:
37 package MyShell;
39 use base qw(Term::Shell); # or manually edit @MyShell::ISA.
40 sub run_exec {
42 my ($o, $cmd, @args) = @_;
43 if ($cmd ne $0) {
44 print "I'm sorry you're leaving us...\n";
45 }
46 exec $cmd, @args;
47 exit 1;
48 }
49 When Term::Shell needs to handle the "exec" command, it will invoke
51 this method. That's all there is to it! You write handlers, and
52 Term::Shell handles the gory details.
53
55 How do you bring your shell to life? Assuming the package "MyShell"
56 contains your actions, just do this:
57 use MyShell;
59 my $shell = MyShell->new;
60 # Setup code here (if you wish)
62 # Invoke the shell
64 $shell->cmdloop;
65 # Cleanup code here (if you wish)
67 Most people put the setup code in the shell itself, so you can usually
69 get away with this:
70 use MyShell;
72 MyShell->new->cmdloop;
73 It's that simple! All the actions and command handlers go in
75 "MyShell.pm", and your main program is simple. In fact, it's so simple
76 that some people like to write both the actions and the invocation in
77 the same file:
78 package main;
80 MyShell->new->cmdloop;
81 package MyShell;
83 use base qw(Term::Shell);
84 # Actions here
86 Adding commands to your shell is just as easy, if not easier.
88
90 For every command "foo", Term::Shell needs a method called "run_foo()",
91 where 'foo' is what the user will type in. The method will be called
92 with the Term::Shell object as the first parameter, followed by any
93 arguments the user typed after the command.
94 Several prefixes other than "run_" are supported; each prefix tells
96 Term::Shell to call that handler under different circumstances. The
97 following list enumerates all the "special" prefixes. Term::Shell will
98 ignore any method that doesn't start with a prefix listed here.
99 1. run_foo()
101 Adds the command "foo" to the list of supported commands. The
103 method's return value is saved by Term::Shell, but is not used.
104 The method is called with the Term::Shell object as its first
106 argument, followed by any arguments the user typed in.
107 Special case: if you provide a method "run_()", Term::Shell will
109 call it whenever the user enters a blank line. A blank line is
110 anything which matches the regular expression "/^\s*$/".
111 2. help_foo()
113 Adds the command "foo" to the list of help topics. This means the
115 user may enter 'help foo' and get a help screen. It should return a
116 single string to be displayed to the user.
117 The method is called with the Term::Shell object as its first
119 argument, followed by any arguments the user typed in after 'help
120 foo'. You can implement hierarchical help documents by using the
121 arguments.
122 If you do not provide a "help_foo()" method, typing 'help foo'
124 produces an error message.
125 3. smry_foo()
127 Should return a one-line summary of "foo", to be displayed in the
129 help screen.
130 This method is called with the Term::Shell object as its first
132 argument, and no other arguments.
133 If you do not provide a "smry_foo()" method, then the string
135 'undocumented' is used instead.
136 4. comp_foo()
138 Provides custom tab-completion for "foo". That means if the user
140 types 'foo ' and then hits <TAB>, this method will be called. It
141 should return an array reference containing a list of possible
142 completions.
143 This method is called with the Term::Shell object as its first
145 argument, followed by the three arguments:
146 1. $word
148 The word the user is trying to complete.
150 2. $line
152 The line as typed by the user so far.
154 3. $start
156 The offset into $line where $word starts.
158 If you do not provide "comp_foo()", Term::Shell will always return
160 no completions for "foo".
161 Special case: if you provide "comp_()", Term::Shell will call it
163 when the user is trying to complete the name of a command.
164 Term::Shell provides a default "comp_()" method, which completes
165 the actions that you have written handlers for. If you want to
166 provide tab-completion for commands that do not have handlers,
167 override "comp_()".
168 5. alias_foo()
170 Returns a list of aliases for "foo". When one of the aliases is
172 used instead of "foo", the corresponding handler for "foo" is
173 called.
174 6. catch_run()
176 catch_help()
178 catch_comp()
180 catch_smry()
182 Called when an undefined action is entered by the user. Normally
184 when the user enters an unrecognized command, Term::Shell will
185 print an error message and continue.
186 This method is called with the Term::Shell object, the command
188 typed by the user, and then the arguments which would normally be
189 passed to the real handler.
190 The "catch_" methods may do anything the original function would
192 have done. If you want, you can implement all the commands in it,
193 but that means you're doing more work than you have to. Be lazy.
194 When you want something done right...
196 You sometimes have to do it yourself. Introducing add_handlers().
197 Naturally, it adds a handler to the list of defined handlers in the
198 shell.
199 Term::Shell can't always find the commands you want to implement by
201 searching the inheritance tree. Having an AUTOLOAD() method, for
202 instance, will break this system. In that situation, you may wish to
203 tell Term::Shell about the extra commands available using
204 add_handlers():
205 package MyShell;
207 use base qw(Term::Shell);
208 sub AUTOLOAD {
210 if ($AUTOLOAD =~ /::run_fuzz$/) {
211 # code for 'fuzz' command
212 }
213 elsif ($AUTOLOAD =~ /::run_foozle$/) {
214 # code for 'foozle' command
215 }
216 }
217 sub init {
219 my $o = shift;
220 $o->add_handlers("run_fuzz", "run_foozle");
221 }
222 There are other ways to do this. You could write a "catch_run" routine
224 and do the same thing from there. You'd have to override "comp_" so
225 that it would complete on "foozle" and "fuzz". The advantage to this
226 method is that it adds the methods to the list of commands, so they
227 show up in the help menu and you get completion for free.
228
230 You're probably thinking "just don't write them". But remember, you can
231 inherit from another shell class, and that parent may define commands
232 you want to disable. Term::Shell provides a simple method to make
233 itself forget about commands it already knows about:
234 1. remove_commands()
236 Removes all handlers associated with the given command (or list of
238 commands).
239 For example, Term::Shell comes with two commands ("exit" and
241 "help") implemented with seven handlers:
242 1. smry_exit()
244 2. help_exit()
246 3. run_exit()
248 4. smry_help()
250 5. help_help()
252 6. comp_help()
254 7. run_help()
256 If you want to create a shell that doesn't implement the "help"
258 command, your code might look something like this example:
259 package MyShell;
261 use base qw(Term::Shell);
262 sub init {
264 my $o = shift;
265 $o->remove_commands("help");
266 }
267 # ... define more handlers here ...
269 2. remove_handlers()
271 Removes the given handler (or handlers) from the list of defined
273 commands. You have to specify a full handler name, including the
274 'run_' prefix. You can obviously specify any of the other prefixes
275 too.
276 If you wanted to remove the help for the "exit" command, but
278 preserve the command itself, your code might look something like
279 this:
280 package MyShell;
282 use base qw(Term::Shell);
283 sub init {
285 my $o = shift;
286 $o->remove_handlers("help_exit");
287 }
288 # ... define more handlers here ...
290 Cover Your Tracks
292 If you do remove built in commands, you should be careful not to let
293 Term::Shell print references to them. Messages like this are guaranteed
294 to confuse people who use your shell:
295 shell> help
297 Unknown command 'help'; type 'help' for a list of commands.
298 Here's the innocuous looking code:
300 package MyShell;
302 use base qw(Term::Shell);
303 sub init {
305 my $o = shift;
306 $o->remove_commands("help");
307 }
308 MyShell->new->cmdloop;
310 The problem is that Term::Shell has to print an error message, and by
312 default it tells the user to use the "help" command to see what's
313 available. If you remove the "help" command, you still have to clean up
314 after yourself and tell Term::Shell to change its error messages:
315 1. msg_unknown_cmd()
317 Called when the user has entered an unrecognized command, and no
319 action was available to satisfy it. It receives the object and the
320 command typed by the user as its arguments. It should return an
321 error message; by default, it is defined thusly:
322 sub msg_unknown_cmd {
324 my ($o, $cmd) = @_;
325 <<END;
326 Unknown command '$cmd'; type 'help' for a list of commands.
327 END
328 }
329 2. msg_ambiguous_cmd()
331 Called when the user has entered a command for which more than
333 handler exists. (For example, if both "quit" and "query" are
334 commands, then "qu" is an ambiguous command, because it could be
335 either.) It receives the object, the command, and the possible
336 commands which could complete it. It should return an error
337 message; by default it is defined thusly:
338 sub msg_ambiguous_cmd {
340 my ($o, $cmd, @c) = @_;
341 local $" = "\n\t";
342 <<END;
343 Ambiguous command '$cmd': possible commands:
344 @c
345 END
346 }
347
349 Shell classes can use any of the methods in this list. Any other
350 methods in Term::Shell may change.
351 1. new()
353 Creates a new Term::Shell object. It currently does not use its
355 arguments. The arguments are saved in '$o->{API}{args}', in case
356 you want to use them later.
357 my $sh = Term::Shell->new(@arbitrary_args);
359 2. cmd()
361 cmd($txt);
363 Invokes $txt as if it had been typed in at the prompt.
365 $sh->cmd("echo 1 2 3");
367 3. cmdloop()
369 mainloop()
371 Repeatedly prompts the user, reads a line, parses it, and invokes a
373 handler. Uses "cmd()" internally.
374 MyShell->new->cmdloop;
376 mainloop() is a synonym for cmdloop(), provided for backwards
378 compatibility. Earlier (unreleased) versions of Term::Shell have
379 only provided mainloop(). All documentation and examples use
380 cmdloop() instead.
381 4. init()
383 fini()
385 Do any initialization or cleanup you need at shell creation
387 (init()) and destruction (fini()) by defining these methods.
388 No parameters are passed.
390 5. preloop()
392 postloop()
394 Do any initialization or cleanup you need at shell startup
396 (preloop()) and shutdown (postloop()) by defining these methods.
397 No parameters are passed.
399 6. precmd()
401 postcmd()
403 Do any initialization or cleanup before and after calling each
405 handler.
406 The parameters are:
408 1. $handler
410 A reference to the name of the handler that is about to be
412 executed.
413 Passed by reference so you can control which handler will be
415 called.
416 2. $cmd
418 A reference to the command as the user typed it.
420 Passed by reference so you can set the command. (If the handler
422 is a "catch_" command, it can be fooled into thinking the user
423 typed some other command, for example.)
424 3. $args
426 The arguments as typed by the user. This is passed as an array
428 reference so that you can manipulate the arguments received by
429 the handler.
430 sub precmd {
432 my $o = shift;
433 my ($handler, $cmd, @args) = @_;
434 # ...
435 }
436 7. stoploop()
438 Sets a flag in the Term::Shell object that breaks out of cmdloop().
440 Note that cmdloop() resets this flag each time you call it, so code
441 like this will work:
442 my $sh = MyShell->new;
444 $sh->cmdloop; # an interactive session
445 $sh->cmdloop; # prompts the user again
446 Term::Shell's built-in run_exit() command just calls stoploop().
448 8. idle()
450 If you set "check_idle" to a non-zero number (see "The Term::Shell
452 Object") then this method is called every "check_idle" seconds. The
453 idle() method defined in Term::Shell does nothing -- it exists only
454 to be redefined in subclasses.
455 package MyShell;
457 use base qw(Term::Shell);
458 sub init {
460 my $o = shift;
461 $o->{API}{check_idle} = 0.1; # 10/s
462 }
463 sub idle {
465 print "Idle!\n";
466 }
467 9. prompt_str()
469 Returns a string to be used as the prompt. prompt_str() is called
471 just before calling the readline() method of Term::ReadLine. If you
472 do not override this method, the string `shell> ' is used.
473 package MyShell;
475 use base qw(Term::Shell);
476 sub prompt_str { "search> " }
478 10. prompt()
480 Term::Shell provides this method for convenience. It's common for a
482 handler to ask the user for more information. This method makes it
483 easy to provide the user with a different prompt and custom
484 completions provided by you.
485 The prompt() method takes the following parameters:
487 1. $prompt
489 The prompt to display to the user. This can be any string you
491 want.
492 2. $default
494 The default value to provide. If the user enters a blank line
496 (all whitespace characters) then the this value will be
497 returned.
498 Note: unlike ExtUtils::MakeMaker's prompt(), Term::Shell's
500 prompt() does not modify $prompt to indicate the $default
501 response. You have to do that yourself.
502 3. $completions
504 An optional list of completion values. When the user hits
506 <TAB>, Term::Shell prints the completions which match what
507 they've typed so far. Term::Shell does not enforce that the
508 user's response is one of these values.
509 4. $casei
511 An optional boolean value which indicates whether the
513 completions should be matched case-insensitively or not. A true
514 value indicates that "FoO" and "foo" should be considered the
515 same.
516 prompt() returns the unparsed line to give you maximum flexibility.
518 If you need the line parsed, use the line_parsed() method on the
519 return value.
520 11. cmd_prefix()
522 cmd_suffix()
524 These methods should return a prefix and suffix for commands,
526 respectively. For instance, an IRC client will have a prefix of
527 "/". Most shells have an empty prefix and suffix.
528 12. page()
530 page($txt)
532 Prints $txt through a pager, prompting the user to press a key for
534 the next screen full of text.
535 13. line()
537 line_parsed()
539 Although "run_foo()" is called with the parsed arguments from the
541 command-line, you may wish to see the raw command-line. This is
542 available through the line() method. If you want to retrieve the
543 parsed line again, use line_parsed().
544 line_parsed() accepts an optional string parameter: the line to
546 parse. If you have your own line to parse, you can pass it to
547 line_parsed() and get back a list of arguments. This is useful
548 inside completion methods, since you don't get a parsed list there.
549 14. run()
551 If you want to run another handler from within a handler, and you
553 have pre-parsed arguments, use run() instead of cmd(). cmd() parses
554 its parameter, whereas run() takes each element as a separate
555 parameter.
556 It needs the name of the action to run and any arguments to pass to
558 the handler.
559 Term::Shell uses this method internally to invoke command handlers.
561 15. help()
563 If you want to get the raw text of a help message, use help(). It
565 needs the name of the help topic and any arguments to pass to the
566 handler.
567 Term::Shell uses this method internally to invoke help handlers.
569 16. summary()
571 If you want to get the summary text of an action, use summary(). It
573 needs the name of the action.
574 Term::Shell uses this method internally to display the help page.
576 17. possible_actions()
578 You will probably want this method in comp_foo().
580 possible_actions() takes a word and a list, and returns a list of
581 possible matches. Term::Shell uses this method internally to decide
582 which handler to run when the user enters a command.
583 There are several arguments, but you probably won't use them all in
585 the simple cases:
586 1. $needle
588 The (possible incomplete) word to try to match against the list
590 of actions (the haystack).
591 2. $type
593 The type with which to prefix $action. This is useful when
595 completing a real action -- you have to specify whether you
596 want it to look for "run_" or "help_" or something else. If you
597 leave it blank, it will use $action without prefixing it.
598 3. $strip
600 If you pass in a true value here, possible_actions() will
602 remove an initial $type from the beginning of each result
603 before returning the results. This is useful if you want to
604 know what the possible "run_" commands are, but you don't want
605 to have the "run_" in the final result.
606 If you do not specify this argument, it uses '0' (the default
608 is not to strip the results).
609 4. $haystack
611 You can pass in a reference to a list of strings here. Each
613 string will be compared with $needle.
614 If you do not specify this argument, it uses the list of
616 handlers. This is how Term::Shell matches commands typed in by
617 the user with command handlers written by you.
618 18. print_pairs()
620 This overloaded beast is used whenever Term::Shell wants to print a
622 set of keys and values. It handles wrapping long values, indenting
623 the whole thing, inserting the separator between the key and value,
624 and all the rest.
625 There are lots of parameters, but most of them are optional:
627 1. $keys
629 A reference to a list of keys to print.
631 2. $values
633 A reference to a list of values to print.
635 3. $sep
637 The string used to separate the keys and values. If omitted, ':
639 ' is used.
640 4. $left
642 The justification to be used to line up the keys. If true, the
644 keys will be left-justified. If false or omitted, the keys will
645 be right-justified.
646 5. $ind
648 A string used to indent the whole paragraph. Internally,
650 print_pairs() uses length(), so you shouldn't use tabs in the
651 indent string. If omitted, the empty string is used (no
652 indent).
653 6. $len
655 An integer which describes the minimum length of the keys.
657 Normally, print_pairs() calculates the longest key and assigns
658 the column width to be as wide as the longest key plus the
659 separator. You can force the column width to be larger using
660 $len. If omitted, 0 is used.
661 7. $wrap
663 A boolean which indicates whether the value should be text-
665 wrapped using Text::Autoformat. Text is only ever wrapped if it
666 contains at least one space. If omitted, 0 is used.
667 8. $cols
669 An integer describing the number of columns available on the
671 current terminal. Normally 78 is used, or the environment
672 variable COLUMNS, but you can override the number here to
673 simulate a right-indent.
674 19. term()
676 Returns the underlying "Term::ReadLine" object used to interact
678 with the user. You can do powerful things with this object; in
679 particular, you will cripple Term::Shell's completion scheme if you
680 change the completion callback function.
681 20. process_esc()
683 This method may be overridden to provide shell-like escaping of
685 backslashes inside quoted strings. It accepts two parameters:
686 1. $c
688 The character which was escaped by a backslash.
690 2. $quote
692 The quote character used to delimit this string. Either """ or
694 "'".
695 This method should return the string which should replace the
697 backslash and the escaped character.
698 By default, process_esc() uses escaping rules similar to Perl's
700 single-quoted string:
701 1. Escaped backslashes return backslashes. The string "123\\456"
703 returns "123\456".
704 2. Escaped quote characters return the quote character (to allow
706 quote characters in strings). The string "abc\"def" returns
707 "abc"def".
708 3. All other backslashes are returned verbatim. The string
710 "123\456" returns "123\456".
711 Term::Shell's quote characters cannot be overridden, unless you
713 override line_parsed(): they are """ or "'". This may change in a
714 future version of Term::Shell.
715 21. add_handlers()
717 See "Adding Commands to Your Shell" for information on
719 add_handlers().
720 22. remove_commands()
722 remove_handlers()
724 See "Removing Commands from Your Shell" for information on
726 remove_handlers().
727
729 Term::Shell creates a hash based Perl object. The object contains
730 information like what handlers it found, the underlying Term::ReadLine
731 object, and any arguments passed to the constructor.
732 This hash is broken into several subhashes. The only two subhashes that
734 a Shell should ever use are $o->{API} and $o->{SHELL}. The first one
735 contains all the information that Term::Shell has gathered for you. The
736 second one is a private area where your Shell can freely store data
737 that it might need later on.
738 This section will describe all the Term::Shell object "API" attributes:
740 The args Attribute
742 This an array reference containing any arguments passed to the
743 Term::Shell constructor.
744 The case_ignore Attribute
746 This boolean controls whether commands should be matched without regard
747 to case. If this is true, then typing "FoO" will have the same effect
748 as typing "foo".
749 Defaults to true on MSWin32, and false on other platforms.
751 The class Attribute
753 The class of the object. This is probably the package containing the
754 definition of your shell, but if someone subclasses your shell, it's
755 their class.
756 The command Attribute
758 Whenever Term::Shell invokes an action, it stores information about the
759 action in the "command" attribute. Information about the last "run"
760 action to be invoked is stored in $o->{API}{command}{run}. The
761 information itself is stored in a subhash containing these fields:
762 name
764 The name of the command, as typed by the user.
765 found
767 The a boolean value indicating whether a handler could be found.
768 handler
770 The full name of the handler, if found.
771 Note that this facility only stores information about the last action
773 to be executed. It's good enough for retrieving the information about
774 the last handler which ran, but not for much else.
775 The following example shows a case where "run_foo()" calls "run_add()",
777 and prints its return value (in this case, 42).
778 sub run_foo {
780 my $o = shift;
781 my $sum = $o->run("add", 21, 21);
782 print "21 + 21 = ", $sum, "\n";
783 }
784 sub run_add {
786 my $o = shift;
787 my $sum = 0;
788 $sum += $_ for @_;
789 print "add(): sum = $sum\n";
790 return $sum;
791 }
792 At the end of run_foo(), $o->{API}{command}{run}{handler} contains the
794 string "run_add".
795 The match_uniq Attribute
797 This boolean controls whether the user can type in only enough of the
798 command to make it unambiguous. If true, then if the shell has the
799 commands "foo" and "bar" defined, the user can type "f" to run "foo",
800 and "b" to run "bar".
801 Defaults to true.
803 The readline Attribute
805 Which Term::ReadLine module is being used. Currently, this is always
806 one of "Term::ReadLine::Stub", "Term::ReadLine::Perl", or
807 "Term::ReadLine::Gnu".
808 The script Attribute
810 The name of the script that invoked your shell.
811 The version Attribute
813 The version of Term::Shell you are running under.
814
816 For more information about the underlying ReadLine module, see
817 Term::ReadLine. You may also want to look at Term::ReadLine::Gnu and
818 Term::ReadLine::Perl.
819 For more information about the underlying formatter used by
821 print_pairs(), see Text::Autoformat.
822 The API for Term::Shell was inspired by (gasp!) a Python package called
824 "cmd". For more information about this package, please look in the
825 Python Library Reference, either in your Python distribution or at
826 <https://docs.python.org/3/library/cmd.html> .
827
829 Neil Watkiss (NEILW@cpan.org)
830
832 Copyright (c) 2001, Neil Watkiss. All Rights Reserved.
833 All Rights Reserved. This module is free software. It may be used,
835 redistributed and/or modified under the same terms as Perl itself.
836 See http://www.perl.com/perl/misc/Artistic.html
838
840 Websites
841 The following websites have more information about this module, and may
842 be of help to you. As always, in addition to those websites please use
843 your favorite search engine to discover more resources.
844 • MetaCPAN
846 A modern, open-source CPAN search engine, useful to view POD in
848 HTML format.
849 <https://metacpan.org/release/Term-Shell>
851 • RT: CPAN's Bug Tracker
853 The RT ( Request Tracker ) website is the default bug/issue
855 tracking system for CPAN.
856 <https://rt.cpan.org/Public/Dist/Display.html?Name=Term-Shell>
858 • CPANTS
860 The CPANTS is a website that analyzes the Kwalitee ( code metrics )
862 of a distribution.
863 <http://cpants.cpanauthors.org/dist/Term-Shell>
865 • CPAN Testers
867 The CPAN Testers is a network of smoke testers who run automated
869 tests on uploaded CPAN distributions.
870 <http://www.cpantesters.org/distro/T/Term-Shell>
872 • CPAN Testers Matrix
874 The CPAN Testers Matrix is a website that provides a visual
876 overview of the test results for a distribution on various
877 Perls/platforms.
878 <http://matrix.cpantesters.org/?dist=Term-Shell>
880 • CPAN Testers Dependencies
882 The CPAN Testers Dependencies is a website that shows a chart of
884 the test results of all dependencies for a distribution.
885 <http://deps.cpantesters.org/?module=Term::Shell>
887 Bugs / Feature Requests
889 Please report any bugs or feature requests by email to "bug-term-shell
890 at rt.cpan.org", or through the web interface at
891 <https://rt.cpan.org/Public/Bug/Report.html?Queue=Term-Shell>. You will
892 be automatically notified of any progress on the request by the system.
893 Source Code
895 The code is open to the world, and available for you to hack on. Please
896 feel free to browse it and play with it, or whatever. If you want to
897 contribute patches, please send me a diff or prod me to pull from your
898 repository :)
899 <https://github.com/shlomif/Term-Shell>
901 git clone git://git@github.com:shlomif/Term-Shell.git
903
905 Shlomi Fish <shlomif@cpan.org>
906
908 Please report any bugs or feature requests on the bugtracker website
909 <http://rt.cpan.org/NoAuth/Bugs.html?Dist=Term-Shell> or by email to
910 bug-term-shell@rt.cpan.org <mailto:bug-term-shell@rt.cpan.org>.
911 When submitting a bug or request, please include a test-file or a patch
913 to an existing test-file that illustrates the bug or desired feature.
914
916 This software is copyright (c) 2001 by Neil Watkiss.
917 This is free software; you can redistribute it and/or modify it under
919 the same terms as the Perl 5 programming language system itself.
920perl v5.32.1 2021-01-27 Term::Shell(3)