🏃 runs: a better subprocess 🏃

runs has improved versions of call(), check_call(), check_output(), and run() from Python's subprocess module that handle multiple commands and blocks of text, fix some defects, and add some features.

.. code-block:: python

import runs

runs('''
    ls
    df -k  # or perhaps -h?
    echo 'Done and done'
''')

subprocess is essential but:

• You can only run one command at a time

• Commands to subprocess must be either a sequence of strings or a string, depending on whether shell=True or not

• Results are returned by default as bytes and not strings

The runs functions let you run a block of text as a sequence of subprocess calls.

runs provides call-compatible replacements for the functions subprocess.call(), subprocess.check_call(), subprocess.check_output(), and subprocess.run()

Each replacement function takes a block of text, which is split into individual command lines, or a list of commands, and returns a list of values, one for each command. A block of text can contain line continuations, and comments, which are ignored.

The replacement functions also add optional logging, error handling, and lazy evaluation, and use UTF-8 encoding by default.

The module runs is callable - runs() is a synonym for runs.run().

EXAMPLES:

.. code-block:: python

# ``runs()`` or ``runs.run()`` writes to stdout and stderr just as if you'd run
# the commands from the terminal

import runs

runs('echo "hello, world!"')  # prints hello, world!

# runs.check_output() returns a list, one string result for each command

results = check_output('''
    echo  line   one  # Here's line one.
    echo   'line "  two  "'  # and two!
''')
assert results == ['line one', 'line "  two  "']

# Line continuations work too, either single or double
runs('''
    ls -cail

    # One command that takes many lines.
    g++ -DDEBUG  -O0 -g -std=c++17 -pthread -I ./include -lm -lstdc++ \
      -Wall -Wextra -Wno-strict-aliasing -Wpedantic \\
      -MMD -MP -MF -c src/tests.cpp -o build/./src/tests.cpp.o

    echo DONE
 ''')

NOTES:

Exactly like subprocess, runs differs from the shell in a few ways, so you can't just paste your shell scripts in:

• Redirection doesn't work.

.. code-block:: python

result = runs.check_output('echo foo > bar.txt')
assert result == ['foo > bar.txt\n']

• Pipes don't work.

.. code-block:: python

result = runs.check_output('echo foo | wc')
assert result == ['foo | wc \n']

• Environment variables are not expanded in command lines

.. code-block:: python

result = runs.check_output('echo $FOO', env={'FOO': 'bah!'})
assert result == ['$FOO\n']

Environment variables are exported to the subprocess, absolutely, but no environment variable expension happens on command lines.

API

runs()

.. code-block:: python

  runs(
       commands,
       *args,
       iterate=False,
       encoding='utf8',
       on_exception=None,
       echo=False,
       **kwargs,
  )

(`runs.py, 186-200 <https://github.com/rec/runs/blob/master/runs.py#L186-L200>`_)

Call ``subprocess.run()`` on each command.
Return a list of ``subprocess.CompletedProcess`` instances.
See the help for ``subprocess.run()`` for more information.

Arguments:
  commands:
    A string, which gets split into lines on line endings, or a list of
    strings.

  args:
    Positional arguments to ``subprocess.run()`` (but prefer keyword
    arguments!)

  on_exception:
    If ``on_exception`` is ``False``, the default, exceptions from
    ``subprocess.run()`` are raised as usual.

    If ``on_exception`` is True, they are ignored.

    If ``on_exception`` is a callable, the line that caused the exception is
    passed to it.

    If ``on_exception`` is a string, the line causing the exception
    is printed, prefixed with that string.

  echo:
    If ``echo`` is ``False``, the default, then commands are silently executed.
    If ``echo`` is ``True``, commands are printed prefixed with ``$``
    If ``echo`` is a string, commands are printed prefixed with that string
    If ``echo`` is callable, then each command is passed to it.

  iterate:
    If ``iterate`` is ``False``, the default, then a list of results is
    returned.

    Otherwise an iterator of results which is returned, allowing for lazy
    evaluation.

  encoding:
    Like the argument to ``subprocess.run()``, except the default  is
    ``'utf8'``

  kwargs:
    Named arguments passed on to ``subprocess.run()``

``runs.call()``

.. code-block:: python

runs.call( commands, *args, iterate=False, encoding='utf8', on_exception=None, echo=False, **kwargs, )

(runs.py, 186-200 <https://github.com/rec/runs/blob/master/runs.py#L186-L200>_)

Call subprocess.call() on each command. Return a list of integer returncodes, one for each command executed. See the help for subprocess.call() for more information.

Arguments: commands: A string, which gets split into lines on line endings, or a list of strings.

args: Positional arguments to subprocess.call() (but prefer keyword arguments!)

on_exception: If on_exception is False, the default, exceptions from subprocess.call() are raised as usual.

If ``on_exception`` is True, they are ignored.

If ``on_exception`` is a callable, the line that caused the exception is
passed to it.

If ``on_exception`` is a string, the line causing the exception
is printed, prefixed with that string.

echo: If echo is False, the default, then commands are silently executed. If echo is True, commands are printed prefixed with $ If echo is a string, commands are printed prefixed with that string If echo is callable, then each command is passed to it.

iterate: If iterate is False, the default, then a list of results is returned.

Otherwise an iterator of results which is returned, allowing for lazy
evaluation.

encoding: Like the argument to subprocess.call(), except the default is 'utf8'

kwargs: Named arguments passed on to subprocess.call()

runs.check_call()

.. code-block:: python

  runs.check_call(
       commands,
       *args,
       iterate=False,
       encoding='utf8',
       on_exception=None,
       echo=False,
       **kwargs,
  )

(`runs.py, 186-200 <https://github.com/rec/runs/blob/master/runs.py#L186-L200>`_)

Call ``subprocess.check_call()`` on each command.
If any command has a non-zero returncode, raise ``subprocess.CallProcessError``.

See the help for ``subprocess.check_call()`` for more information.

Arguments:
  commands:
    A string, which gets split into lines on line endings, or a list of
    strings.

  args:
    Positional arguments to ``subprocess.check_call()`` (but prefer keyword
    arguments!)

  on_exception:
    If ``on_exception`` is ``False``, the default, exceptions from
    ``subprocess.check_call()`` are raised as usual.

    If ``on_exception`` is True, they are ignored.

    If ``on_exception`` is a callable, the line that caused the exception is
    passed to it.

    If ``on_exception`` is a string, the line causing the exception
    is printed, prefixed with that string.

  echo:
    If ``echo`` is ``False``, the default, then commands are silently executed.
    If ``echo`` is ``True``, commands are printed prefixed with ``$``
    If ``echo`` is a string, commands are printed prefixed with that string
    If ``echo`` is callable, then each command is passed to it.

  iterate:
    If ``iterate`` is ``False``, the default, then a list of results is
    returned.

    Otherwise an iterator of results which is returned, allowing for lazy
    evaluation.

  encoding:
    Like the argument to ``subprocess.check_call()``, except the default  is
    ``'utf8'``

  kwargs:
    Named arguments passed on to ``subprocess.check_call()``

``runs.check_output()``

.. code-block:: python

runs.check_output( commands, *args, iterate=False, encoding='utf8', on_exception=None, echo=False, **kwargs, )

(runs.py, 186-200 <https://github.com/rec/runs/blob/master/runs.py#L186-L200>_)

Call subprocess.check_output() on each command. If a command has a non-zero exit code, raise a subprocess.CallProcessError. Otherwise, return the results as a list of strings, one for each command. See the help for subprocess.check_output() for more information.

Arguments: commands: A string, which gets split into lines on line endings, or a list of strings.

args: Positional arguments to subprocess.check_output() (but prefer keyword arguments!)

on_exception: If on_exception is False, the default, exceptions from subprocess.check_output() are raised as usual.

If ``on_exception`` is True, they are ignored.

If ``on_exception`` is a callable, the line that caused the exception is
passed to it.

If ``on_exception`` is a string, the line causing the exception
is printed, prefixed with that string.

echo: If echo is False, the default, then commands are silently executed. If echo is True, commands are printed prefixed with $ If echo is a string, commands are printed prefixed with that string If echo is callable, then each command is passed to it.

iterate: If iterate is False, the default, then a list of results is returned.

Otherwise an iterator of results which is returned, allowing for lazy
evaluation.

encoding: Like the argument to subprocess.check_output(), except the default is 'utf8'

kwargs: Named arguments passed on to subprocess.check_output()

(automatically generated by doks <https://github.com/rec/doks/>_ on 2020-12-16T13:48:26.579866)