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.. _cmd-source:
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source - evaluate contents of file
==================================
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Synopsis
--------
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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
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.. synopsis ::
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source FILE [ARGUMENTS ...]
SOMECOMMAND | source
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Description
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-----------
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`` source `` evaluates the commands of the specified file in the current shell as a new block of code. This is different from starting a new process to perform the commands (i.e. `` fish < FILE `` ) since the commands will be evaluated by the current shell, which means that changes in shell variables will affect the current shell. If additional arguments are specified after the file name, they will be inserted into the `` $argv `` variable. The `` $argv `` variable will not include the name of the sourced file.
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fish will search the working directory to resolve relative paths but will not search `` $PATH `` .
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If no file is specified and stdin is not the terminal, or if the file name `` - `` is used, stdin will be read.
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The exit status of `` source `` is the exit status of the last job to execute. If something goes wrong while opening or reading the file, `` source `` exits with a non-zero status.
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`` . `` (a single period) is an alias for the `` source `` command. The use of `` . `` is deprecated in favour of `` source `` , and `` . `` will be removed in a future version of fish.
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`` source `` creates a new :ref: `local scope<variables-scope>` ; `` set --local `` within a sourced block will not affect variables in the enclosing scope.
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Example
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-------
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::
source ~/.config/fish/config.fish
# Causes fish to re-read its initialization file.
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Caveats
-------
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In fish versions prior to 2.3.0, the `` $argv `` variable would have a single element (the name of the sourced file) if no arguments are present. Otherwise, it would contain arguments without the name of the sourced file. That behavior was very confusing and unlike other shells such as bash and zsh.
