fish-shell/doc_src/cmds/bg.rst

.. _cmd-bg:

bg - send jobs to background
============================

Synopsis
--------

.. synopsis::

    bg [PID ...]

Description
-----------

``bg`` sends :ref:`jobs <syntax-job-control>` to the background, resuming them if they are stopped.

A background job is executed simultaneously with fish, and does not have access to the keyboard. If no job is specified, the last job to be used is put in the background. If ``PID`` is specified, the jobs containing the specified process IDs are put in the background.

A PID of the format ``%n``, where n is an integer, will be interpreted as the PID of job number n. Job numbers can be seen in the output of :doc:`jobs <jobs>`.

When at least one of the arguments isn't a valid job specifier, ``bg`` will print an error without backgrounding anything.

When all arguments are valid job specifiers, ``bg`` will background all matching jobs that exist.

The **-h** or **--help** option displays help about using this command.

Example
-------

The typical use is to run something, stop it with ctrl-z, and then continue it in the background with bg::

  > find / -name "*.js" >/tmp/jsfiles 2>/dev/null # oh no, this takes too long, let's press Ctrl-z!
  fish: Job 1, 'find / -name "*.js" >/tmp/jsfil…' has stopped
  > bg
  Send job 1 'find / -name "*.js" >/tmp/jsfiles 2>/dev/null' to background
  > # I can continue using this shell!
  > # Eventually:
  fish: Job 1, 'find / -name "*.js" >/tmp/jsfil…' has ended

``bg 123 456 789`` will background the jobs that contain processes 123, 456 and 789.

If only 123 and 789 exist, it will still background them and print an error about 456.

``bg 123 banana`` or ``bg banana 123`` will complain that "banana" is not a valid job specifier.

``bg %2`` will background job 2.
docs: Add labels to all commands This allows us to use :ref: references, which don't require hardcoding it as html [ci skip] 2019-03-31 17:05:09 +08:00			`.. _cmd-bg:`

Switch command docs from \section to reStructuredText 2018-12-17 09:39:33 +08:00			`bg - send jobs to background`
Fix command section separator line lengths 2019-01-03 12:10:47 +08:00			`============================`
Switch command docs from \section to reStructuredText 2018-12-17 09:39:33 +08:00
Migrate the 'synopsis' sections to .rst format 2018-12-18 09:58:24 +08:00			`Synopsis`
			`--------`
Copy doc_src to sphinx_doc_src and add a TOC 2018-12-17 05:08:41 +08:00
docs synopsis: add HTML highlighing and automate manpage markup Recent synopsis changes move from literal code blocks to [RST line blocks]. This does not translate well to HTML: it's not rendered in monospace, so aligment is lost. Additionally, we don't get syntax highlighting in HTML, which adds differences to our code samples which are highlighted. We hard-wrap synopsis lines (like code blocks). To align continuation lines in manpages we need [backslashes in weird places]. Combined with the *, , and `` markup, it's a bit hard to get the alignment right. Fix these by moving synopsis sources back to code blocks and compute HTML syntax highlighting and manpage markup with a custom Sphinx extension. The new Pygments lexer can tokenize a synopsis and assign the various highlighting roles, which closely matches fish's syntax highlighing: - command/keyword (dark blue) - parameter (light blue) - operator like and/or/not/&&/\|\| (cyan) - grammar metacharacter (black) For manpage output, we don't project the fish syntax highlighting but follow the markup convention in GNU's man(1): bold text type exactly as shown. italic text replace with appropriate argument. To make it easy to separate these two automatically, formalize that (italic) placeholders must be uppercase; while all lowercase text is interpreted literally (so rendered bold). This makes manpages more consistent, see string-join(1) and and(1). Implementation notes: Since we want manpage formatting but Sphinx's Pygments highlighing plugin does not support manpage output, add our custom "synopsis" directive. This directive parses differently when manpage output is specified. This means that the HTML and manpage build processes must not share a cache, because the parsed doctrees are cached. Work around this by using separate cache locations for build targets "sphinx-docs" (which creates HTML) and "sphinx-manpages". A better solution would be to only override Sphinx's ManualPageBuilder but that would take a bit more code (ideally we could override ManualPageWriter but Sphinx 4.3.2 doesn't really support that). --- Alternative solution: stick with line blocks but use roles like :command: or :option: (or custom ones). While this would make it possible to produce HTML that is consistent with code blocks (by adding a bit of CSS), the source would look uglier and is harder to maintain. (Let's say we want to add custom formatting to the [\|] metacharacters in HTML. This is much easier with the proposed patch.) --- [RST line blocks]: https://docutils.sourceforge.io/docs/ref/rst/restructuredtext.html#line-blocks [backslashes in weird places]: https://github.com/fish-shell/fish-shell/pull/8626#discussion_r782837750 2022-01-09 22:09:46 +08:00			`.. synopsis::`

			`bg [PID ...]`
Copy doc_src to sphinx_doc_src and add a TOC 2018-12-17 05:08:41 +08:00
Convert \\subsection sections into rst format 2018-12-19 10:44:30 +08:00			`Description`
Fix command section separator line lengths 2019-01-03 12:10:47 +08:00			`-----------`
Copy doc_src to sphinx_doc_src and add a TOC 2018-12-17 05:08:41 +08:00
Fix broken links to index.html in cmd docs 2020-01-31 11:38:56 +08:00			``bg`` sends :ref:`jobs <syntax-job-control>` to the background, resuming them if they are stopped.
Copy doc_src to sphinx_doc_src and add a TOC 2018-12-17 05:08:41 +08:00
docs: note job expansion in bg/fg/jobs arguments Discussed in #5019. 2021-02-28 20:56:23 +08:00			A background job is executed simultaneously with fish, and does not have access to the keyboard. If no job is specified, the last job to be used is put in the background. If ``PID`` is specified, the jobs containing the specified process IDs are put in the background.
Copy doc_src to sphinx_doc_src and add a TOC 2018-12-17 05:08:41 +08:00
docs: Improve bg docs Show an actual session here, to explain what you would actually do with it. 2023-06-06 00:25:48 +08:00			A PID of the format ``%n``, where n is an integer, will be interpreted as the PID of job number n. Job numbers can be seen in the output of :doc:`jobs <jobs>`.
docs: note job expansion in bg/fg/jobs arguments Discussed in #5019. 2021-02-28 20:56:23 +08:00
docs: Improve bg docs Show an actual session here, to explain what you would actually do with it. 2023-06-06 00:25:48 +08:00			When at least one of the arguments isn't a valid job specifier, ``bg`` will print an error without backgrounding anything.
Copy doc_src to sphinx_doc_src and add a TOC 2018-12-17 05:08:41 +08:00
docs: note job expansion in bg/fg/jobs arguments Discussed in #5019. 2021-02-28 20:56:23 +08:00			When all arguments are valid job specifiers, ``bg`` will background all matching jobs that exist.
Copy doc_src to sphinx_doc_src and add a TOC 2018-12-17 05:08:41 +08:00
docs: omnibus cleanup Includes harmonizing the display of options and arguments, standardising terminology, using the envvar directive more broadly, adding help options to all commands that support them, simplifying some language, and tidying up multiple formatting issues. string documentation is not changed. 2022-03-12 00:18:41 +08:00			`The -h or --help option displays help about using this command.`

Convert \\subsection sections into rst format 2018-12-19 10:44:30 +08:00			`Example`
Fix command section separator line lengths 2019-01-03 12:10:47 +08:00			`-------`
Copy doc_src to sphinx_doc_src and add a TOC 2018-12-17 05:08:41 +08:00
docs: Improve bg docs Show an actual session here, to explain what you would actually do with it. 2023-06-06 00:25:48 +08:00			`The typical use is to run something, stop it with ctrl-z, and then continue it in the background with bg::`

			`> find / -name "*.js" >/tmp/jsfiles 2>/dev/null # oh no, this takes too long, let's press Ctrl-z!`
			`fish: Job 1, 'find / -name "*.js" >/tmp/jsfil…' has stopped`
			`> bg`
			`Send job 1 'find / -name "*.js" >/tmp/jsfiles 2>/dev/null' to background`
			`> # I can continue using this shell!`
			`> # Eventually:`
			`fish: Job 1, 'find / -name "*.js" >/tmp/jsfil…' has ended`

docs: note job expansion in bg/fg/jobs arguments Discussed in #5019. 2021-02-28 20:56:23 +08:00			``bg 123 456 789`` will background the jobs that contain processes 123, 456 and 789.
Copy doc_src to sphinx_doc_src and add a TOC 2018-12-17 05:08:41 +08:00
			`If only 123 and 789 exist, it will still background them and print an error about 456.`

Switch backticks to double backticks for rst compatibility 2018-12-20 04:02:45 +08:00			``bg 123 banana`` or ``bg banana 123`` will complain that "banana" is not a valid job specifier.
docs: note job expansion in bg/fg/jobs arguments Discussed in #5019. 2021-02-28 20:56:23 +08:00
docs: Improve bg docs Show an actual session here, to explain what you would actually do with it. 2023-06-06 00:25:48 +08:00			``bg %2`` will background job 2.