Complete::Bash - Completion routines for bash shell
This document describes version 0.335 of Complete::Bash (from Perl distribution Complete-Bash), released on 2020-04-16.
This module provides routines related to tab completion in bash shell.
Bash allows completion to come from various sources. The simplest is from a list of words (-W):
-W
% complete -W "one two three four" somecmd % somecmd t<Tab> two three
Another source is from a bash function (-F). The function will receive input in two variables: COMP_WORDS (array, command-line chopped into words) and COMP_CWORD (integer, index to the array of words indicating the cursor position). It must set an array variable COMPREPLY that contains the list of possible completion:
-F
COMP_WORDS
COMP_CWORD
COMPREPLY
% _foo() { local cur COMPREPLY=() cur=${COMP_WORDS[COMP_CWORD]} COMPREPLY=($( compgen -W '--help --verbose --version' -- $cur ) ) } % complete -F _foo foo % foo <Tab> --help --verbose --version
And yet another source is an external command (-C) including, from a Perl script. The command receives two environment variables: COMP_LINE (string, raw command-line) and COMP_POINT (integer, cursor location). Program must split COMP_LINE into words, find the word to be completed, complete that, and return the list of words one per-line to STDOUT. An example:
-C
COMP_LINE
COMP_POINT
% cat foo-complete #!/usr/bin/perl use Complete::Bash qw(parse_cmdline format_completion); use Complete::Util qw(complete_array_elem); my ($words, $cword) = @{ parse_cmdline() }; my $res = complete_array_elem(array=>[qw/--help --verbose --version/], word=>$words->[$cword]); print format_completion($res); % complete -C foo-complete foo % foo --v<Tab> --verbose --version
First of all, parse_cmdline() is the function to parse raw command-line (such as what you get from bash in COMP_LINE environment variable) into words. This makes it easy for the other functions to generate completion answer. See the documentation for that function for more details.
parse_cmdline()
format_completion() is what you use to format completion answer structure for bash.
format_completion()
Usage:
format_completion($completion, $opts) -> str|array
Format completion for output (for shell).
Bash accepts completion reply in the form of one entry per line to STDOUT. Some characters will need to be escaped. This function helps you do the formatting, with some options.
This function accepts completion answer structure as described in the Complete POD. Aside from words, this function also recognizes these keys:
Complete
words
This function is not exported by default, but exportable.
Arguments ('*' denotes required arguments):
$completion* => hash|array
Completion answer structure.
Either an array or hash. See function description for more details.
$opts => hash
Specify options.
Known options:
as
Either string (the default) or array (to return array of lines instead of the lines joined together). Returning array is useful if you are doing completion inside Term::ReadLine, for example, where the library expects an array.
string
array
Term::ReadLine
esc_mode
Escaping mode for entries. Either default (most nonalphanumeric characters will be escaped), shellvar (like default, but dollar sign $ will also be escaped, convenient when completing environment variables for example), filename (currently equals to default), option (currently equals to default), or none (no escaping will be done).
default
shellvar
$
filename
option
none
word
A workaround. String. For now, see source code for more details.
show_summaries
Whether to show item's summaries. Boolean, default is from COMPLETE_BASH_SHOW_SUMMARIES environment variable or 1.
An answer item contain summary, which is a short description about the item, e.g.:
[{word=>"-a" , summary=>"Show hidden files"}, {word=>"-l" , summary=>"Show details"}, {word=>"--sort", summary=>"Specify sort order"}],
When summaries are not shown, user will just be seeing something like:
-a -l --sort
But when summaries are shown, user will see:
-a -- Show hidden files -l -- Show details --sort -- Specify sort order
which is quite helpful.
workaround_with_wordbreaks
Boolean. Default is true. See source code for more details.
Return value: Formatted string (or array, if `as` is set to `array`) (str|array)
join_wordbreak_words() -> [status, msg, payload, meta]
Post-process parse_cmdline() result by joining some words.
parse_cmdline(), like bash, splits some characters that are considered as word-breaking characters:
"'@><=;|&(:
So if command-line is:
command --module=Data::Dump bob@example.org
then they will be parsed as:
["command", "--module", "=", "Data", "::", "Dump", "bob", '@', "example.org"]
Normally in Perl applications, we want :, @ to be part of word. So this routine will convert the above into:
:
@
["command", "--module=Data::Dump", 'bob@example.org']
No arguments.
Returns an enveloped result (an array).
First element (status) is an integer containing HTTP status code (200 means OK, 4xx caller error, 5xx function error). Second element (msg) is a string containing error message, or 'OK' if status is 200. Third element (payload) is optional, the actual result. Fourth element (meta) is called result metadata and is optional, a hash that contains extra information.
Return value: (any)
parse_cmdline($cmdline, $point, $opts) -> array
Parse shell command-line for processing by completion routines.
This function basically converts COMP_LINE (str) and COMP_POINT (int) into something like (but not exactly the same as) COMP_WORDS (array) and COMP_CWORD (int) that bash supplies to shell functions.
The differences with bash are (these differences are mostly for parsing convenience for programs that use this routine; this comparison is made against bash versions 4.2-4.3):
1) quotes and backslashes are stripped (bash's COMP_WORDS contains all the quotes and backslashes);
2) quoted phrase that contains spaces, or phrase that contains escaped spaces is parsed as a single word. For example:
command "First argument" Second\ argument bash would split it as (represented as Perl): ["command", "\"First", "argument\"", "Second\\", "argument"] which is not very convenient. We parse it into: ["command", "First argument", "Second argument"]
3) variables are substituted with their values from environment variables except for the current word (COMP_WORDS[COMP_CWORD]) (bash does not perform variable substitution for COMP_WORDS). However, note that special shell variables that are not environment variables like $0, $_, $IFS will not be replaced correctly because bash does not export those variables for us.
COMP_WORDS[COMP_CWORD]
$0
$_
$IFS
4) tildes (~) are expanded with user's home directory except for the current word (bash does not perform tilde expansion for COMP_WORDS);
~
Caveats:
Like bash, we group non-whitespace word-breaking characters into its own word. By default COMP_WORDBREAKS is:
COMP_WORDBREAKS
So if raw command-line is:
command --foo=bar http://example.com:80 mail@example.org Foo::Bar
then the parse result will be:
["command", "--foo", "=", "bar", "http", ":", "//example.com", ":", "80", "Foo", "::", "Bar"]
which is annoying sometimes. But we follow bash here so we can more easily accept input from a joined COMP_WORDS if we write completion bash functions, e.g. (in the example, foo is a Perl script):
foo
foo () { local words=(${COMPCWORDS[@]}) # add things to words, etc local point=... # calculate the new point COMPREPLY=( COMP_LINE="foo ${words[@]}" COMP_POINT=$point foo ) }
COMP_LINE="foo ${words[@]}" COMP_POINT=$point foo
To avoid these word-breaking characters to be split/grouped, we can escape them with backslash or quote them, e.g.:
command "http://example.com:80" Foo\:\:Bar
which bash will parse as:
["command", "\"http://example.com:80\"", "Foo\:\:Bar"]
and we parse as:
["command", "http://example.com:80", "Foo::Bar"]
Due to the way bash parses the command line (see above), the two below are equivalent:
% cmd --foo=bar % cmd --foo = bar
Because they both expand to ['--foo', '=', 'bar']. But obviously Getopt::Long does not regard the two as equivalent.
['--foo', '=', 'bar']
$cmdline => str
Command-line, defaults to COMP_LINE environment.
Options.
Optional. Known options:
truncate_current_word (bool). If set to 1, will truncate current word to the position of cursor, for example (^ marks the position of cursor): --vers^oo to --vers instead of --versoo. This is more convenient when doing tab completion.
truncate_current_word
^
--vers^oo
--vers
--versoo
$point => int
Point/position to complete in command-line, defaults to COMP_POINT.
Return value: (array)
Return a 2-element array: [$words, $cword]. $words is array of str, equivalent to COMP_WORDS provided by bash to shell functions. $cword is an integer, roughly equivalent to COMP_CWORD provided by bash to shell functions. The word to be completed is at $words->[$cword].
[$words, $cword]
$words
$cword
$words->[$cword]
Note that COMP_LINE includes the command name. If you want the command-line arguments only (like in @ARGV), you need to strip the first element from $words and reduce $cword by 1.
@ARGV
point($cmdline, $marker) -> any
Return line with point marked by a marker.
This is a utility function useful for testing/debugging. parse_cmdline() expects a command-line and a cursor position ($line, $point). This routine expects $line with a marker character (by default it's the caret, ^) and return ($line, $point) to feed to parse_cmdline().
$line
$point
Example:
point("^foo") # => ("foo", 0) point("fo^o") # => ("foo", 2)
Command-line which contains a marker character.
$marker => str (default: "^")
Marker character.
Str. To provide default for the esc_mode option in "format_completion".
Bool. Whether to pass large completion answer to fzf instead of directly passing it to bash and letting bash page it with a simpler more-like internal pager. By default, large is defined as having at least 100 items (same bash's completion-query-items setting). This can be configured via "COMPLETE_BASH_FZF_ITEMS".
completion-query-items
Uint. Default 100. The minimum number of items to trigger passing completion answer to fzf. See also: "COMPLETE_BASH_FZF".
Uint.
Bash will show completion entries in one or several columns, depending on the terminal width and the length of the entries (much like a standard non-long `ls`). If you prefer completion entries to be shown in a single column no matter how wide your terminal is, or how short the entries are, you can set the value of this variable to 1. If you prefer a maximum of two columns, set to 2, and so on. "format_completion" will pad the entries with sufficient spaces to limit the number of columns.
Bool. Will set the default for show_summaries option in "format_completion".
String. Either left (the default) or right.
left
right
The left align looks something like this:
--bar Summary about the bar option --baz Summary about the baz option --foo Summary about the foo option --schapen Summary about the schapen option
The right align will make the completion answer look like what you see in the fish shell:
Bool. If set to true, will produce more log statements to Log::ger.
Please visit the project's homepage at https://metacpan.org/release/Complete-Bash.
Source repository is at https://github.com/perlancar/perl-Complete-Bash.
Please report any bugs or feature requests on the bugtracker website https://rt.cpan.org/Public/Dist/Display.html?Name=Complete-Bash
When submitting a bug or request, please include a test-file or a patch to an existing test-file that illustrates the bug or desired feature.
Complete, the convention that this module follows.
Some higher-level modules that use this module (so you don't have to use this module directly): Getopt::Long::Complete (via Complete::Getopt::Long), Getopt::Long::Subcommand, Perinci::CmdLine (via Perinci::Sub::Complete).
Other modules related to bash shell tab completion: Bash::Completion, Getopt::Complete, Term::Bash::Completion::Generator.
Programmable Completion section in Bash manual: https://www.gnu.org/software/bash/manual/html_node/Programmable-Completion.html
perlancar <perlancar@cpan.org>
This software is copyright (c) 2020, 2019, 2018, 2016, 2015, 2014 by perlancar@cpan.org.
This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.
To install Complete::Bash, copy and paste the appropriate command in to your terminal.
cpanm
cpanm Complete::Bash
CPAN shell
perl -MCPAN -e shell install Complete::Bash
For more information on module installation, please visit the detailed CPAN module installation guide.