2.4. Program Output¶
- PyPI Package
- Documentation
- Git Repository
Literally insert the output of arbitrary commands into documents, helping you to keep your command examples up to date. It consists:
sphinxcontrib.programoutput
: insert command output
2.4.1. Complete output¶
To include the output of a command into your document, use the
.. program-output::
directive provided by this extension.
-
.. program-output::
¶ For more details, see
program-output
directive.- The example
1
.. program-output:: python --version
- Which gives
Python 3.8.0
The whole output of python --version
, including any messages on
standard error, is inserted into the current document, formatted as
literal text without any syntax highlighting. You can omit the content
of the standard error stream with the :nostderr:
option.
By default, commands are executed in the top-level source directory. You can
choose an alternate working directory with the :cwd:
option. The
argument of this option is either a path relative to the current source
file, or a absolute path which means that it is relative to the top level
source directory.
2.4.2. Shortening the output¶
Lengthy output can be shortened with the :ellipsis:
option. Its value
denotes lines to omit when inserting the output of the command. Instead,
a single ellipsis ...
is inserted.
- the example
If used with a single number, all lines after the specified line are omitted:
1 2
.. program-output:: python --help :ellipsis: 2
- which gives
The above omits all lines after the second one:
usage: python [option] ... [-c cmd | -m mod | file | -] [arg] ... Options and arguments (and corresponding environment variables): ...
Negative numbers count from the last line backwards, thus replacing 2
with -2
in the above example would only omit the last two lines.
- the example
If used with two comma-separated line numbers, all lines in between the specified lines are omitted. Again, a negative number counts from the last line backwards:
1 2 3 4
.. program-output:: python --help :caption: First two and last second lines from :command:`python --help` :name: program-output-python-help :ellipsis: 2,-2
- which gives
The above omits all lines except the first two and the last two lines:
usage: python [option] ... [-c cmd | -m mod | file | -] [arg] ... Options and arguments (and corresponding environment variables): ... PYTHONDEVMODE: enable the development mode. PYTHONPYCACHEPREFIX: root directory for bytecode cache (pyc) files.
2.4.3. Mimicking shell input¶
You can mimic shell input with the .. command-output::
directive
1. This directive inserts the command along with its output into
the document.
-
.. command-output::
¶ For more details, see
command-output
directive.- The example
1
.. command-output:: python --version
- Which gives
$ python --version Python 3.8.0
The appearance of this output can be configured with
programoutput_prompt_template
. When used in conjunction with
:ellipsis:
, the command itself and any additional text is never
omitted. :ellipsis:
always refers to the immediate output of the
command.
- the example
1 2 3 4
.. command-output:: python --help :caption: First two lines from :command:`python --help` with prompt :name: command-output-python-help :ellipsis: 2
- which gives
$ python --help usage: python [option] ... [-c cmd | -m mod | file | -] [arg] ... Options and arguments (and corresponding environment variables): ...
2.4.4. Command execution and shell expansion¶
Normally the command is splittet according to the POSIX shell syntax (see
shlex
), and executed directly. Thus special shell features
like expansion of environment variables will not work.
- the example
1
.. command-output:: echo "$USER"
- which gives
$ echo "$USER" $USER
To enable these features, enable the :shell:
option. With this
option, the command is literally passed to the system shell.
- the example
1 2
.. command-output:: echo "$USER" :shell:
- which gives
$ echo "$USER"
Other shell features like process expansion consequently work, too.
- the example
1 2
.. command-output:: ls -l $(which grep) :shell:
- which gives
$ ls -l $(which grep) -rwxr-xr-x 1 root root 219456 Sep 18 2019 /bin/grep
Warning
Remember to use
:shell:
carefully to avoid unintended interpretation of shell syntax and swallowing of fatal errors!
2.4.5. Error handling¶
If an unexpected exit code (also known as return code) is returned by a
command, it is considered to have failed. In this case, a build warning is
emitted to help you to detect misspelled commands or similar errors. By
default, a command is expected to exit with an exit code of 0, all other
codes indicate an error. In some cases however, it may be reasonable to
demonstrate failed programs. To avoid a (superfluous) warning in such a
case, you can specify the expected return code of a command with the
:returncode:
option.
- the example
1 2
.. command-output:: python -c 'import sys, platform; print(sys.version); sys.exit(1)' :returncode: 1
- which gives
$ python -c 'import sys, platform; print(sys.version); sys.exit(1)' 3.8.0 (default, Jan 24 2020, 02:13:43) [GCC 7.4.0]
The above command returns the exit code 1 (as given to
sys.exit()
), but no warning will be emitted. On the
contrary, a warning will be emitted, should the command return 0!
Note
Upon fatal errors which even prevent the execution of the command neither return code nor command output are available. In this case an error message is inserted into the document instead.
If
:shell:
is set however, most of these fatal errors are handled by the system shell and turned into return codes instead. In this case the error message will only appear in the output of the shell. If you’re using:shell:
, double-check the output for errors. Best avoid:shell:
, if possible.
Footnotes
- 1
This directive is just an alias for the
.. program-output::
directive with the:prompt:
option set.