fish-shell/doc_src/cmds/count.rst

.. _cmd-count:

count - count the number of elements of a list
================================================

Synopsis
--------

.. synopsis::

    count STRING1 STRING2 ...
    COMMAND | count
    count [...] < FILE

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

``count`` prints the number of arguments that were passed to it, plus the number of newlines passed to it via stdin. This is usually used to find out how many elements an environment variable list contains, or how many lines there are in a text file.

``count`` does not accept any options, not even ``-h`` or ``--help``.

``count`` exits with a non-zero exit status if no arguments were passed to it, and with zero if at least one argument was passed.

Note that, like ``wc -l``, reading from stdin counts newlines, so ``echo -n foo | count`` will print 0.

Example
-------


::

    count $PATH
    # Returns the number of directories in the users PATH variable.
    
    count *.txt
    # Returns the number of files in the current working directory
    # ending with the suffix '.txt'.

    git ls-files --others --exclude-standard | count
    # Returns the number of untracked files in a git repository

    printf '%s\n' foo bar | count baz
    # Returns 3 (2 lines from stdin plus 1 argument)

    count < /etc/hosts
    # Counts the number of entries in the hosts file
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-count:`

docs: Call "arrays" "lists" We were flip-flopping between the two terms, so we now use one. We still mention "array" in the chapter, and it's still `read --array`, though. Fixes #5846. [ci skip] 2019-05-05 20:01:07 +08:00			`count - count the number of elements of a list`
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::`

docs synopsis: make all placeholder arguments uppercase man(1) uses lowercase placeholders but we usually don't. Additionally, the new synopsis autoformatting only recognizes placeholders if they are uppercase. Use uppercase for all placeholders. 2022-01-17 12:29:49 +08:00			`count STRING1 STRING2 ...`
			`COMMAND \| count`
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			`count [...] < FILE`
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
docs: Call "arrays" "lists" We were flip-flopping between the two terms, so we now use one. We still mention "array" in the chapter, and it's still `read --array`, though. Fixes #5846. [ci skip] 2019-05-05 20:01:07 +08:00			``count`` prints the number of arguments that were passed to it, plus the number of newlines passed to it via stdin. This is usually used to find out how many elements an environment variable list contains, or how many lines there are in a text file.
Copy doc_src to sphinx_doc_src and add a TOC 2018-12-17 05:08:41 +08:00
Switch backticks to double backticks for rst compatibility 2018-12-20 04:02:45 +08:00			``count`` does not accept any options, not even ``-h`` or ``--help``.
Copy doc_src to sphinx_doc_src and add a TOC 2018-12-17 05:08:41 +08:00
Switch backticks to double backticks for rst compatibility 2018-12-20 04:02:45 +08:00			``count`` exits with a non-zero exit status if no arguments were passed to it, and with zero if at least one argument was passed.
Copy doc_src to sphinx_doc_src and add a TOC 2018-12-17 05:08:41 +08:00
[count] Allow counting lines from stdin As a simple replacement for `wc -l`. This counts both lines on stdin _and_ arguments. So if "file" has three lines, then `count a b c < file` will print 6. And since it counts newlines, like wc, `echo -n foo \| count` prints 0. 2018-01-04 07:42:12 +08:00			Note that, like ``wc -l``, reading from stdin counts newlines, so ``echo -n foo \| count`` will print 0.
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			`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

Switch \fish sections to rst format 2018-12-19 11:14:04 +08:00
			`::`

			`count $PATH`
			`# Returns the number of directories in the users PATH variable.`

			`count *.txt`
docs: Make more code lines shorter 2021-02-02 15:35:38 +08:00			`# Returns the number of files in the current working directory`
			`# ending with the suffix '.txt'.`
Switch \fish sections to rst format 2018-12-19 11:14:04 +08:00
[count] Allow counting lines from stdin As a simple replacement for `wc -l`. This counts both lines on stdin _and_ arguments. So if "file" has three lines, then `count a b c < file` will print 6. And since it counts newlines, like wc, `echo -n foo \| count` prints 0. 2018-01-04 07:42:12 +08:00			`git ls-files --others --exclude-standard \| count`
			`# Returns the number of untracked files in a git repository`

			`printf '%s\n' foo bar \| count baz`
			`# Returns 3 (2 lines from stdin plus 1 argument)`

			`count < /etc/hosts`
			`# Counts the number of entries in the hosts file`