Skip to main content

Kids shell command call wrapper

Project description

Latest PyPI version Travis CI build status Test coverage is a Python library providing helpers when calling shell commands thanks to python. It’s part of ‘Kids’ (for Keep It Dead Simple) library.


This is Alpha release. More a place to store common librairies. Will perhaps evolve into something more consistent.

It is, for now, a very humble package.



  • Call wrap() when you want to call a system command and you don’t have to bother about subprocess and other stuff. You get the standard output of the command as the return string.

These assumptions are in the code:

  • You don’t want to deal with precise subprocess things, don’t really need to care about security (because system command you launch are hard-written).

  • You don’t need asynchronous code.


You don’t need to download the GIT version of the code as is available on the PyPI. So you should be able to run:

pip install

If you have downloaded the GIT sources, then you could add install the current version via traditional:

python install

And if you don’t have the GIT sources but would like to get the latest master or branch from github, you could also:

pip install git+

Or even select a specific revision (branch/tag/commit):

pip install git+


More documentation is available in the code.


If command doesn’t fail, standard output is returned:

>>> from __future__ import print_function

>>> from import wrap
>>> print(wrap('test "$HELLO" && echo "foo" || echo "bar"'))

But if command fails, then a special ShellError exception is cast:

>>> wrap('test "$HELLO" && echo "foo" || { echo "bar" ; false ; }')
Traceback (most recent call last):
ShellError: Wrapped command returned with unexpected errorlevel.
  command: 'test "$HELLO" && echo "foo" || { echo "bar" ; false ; }'
  errlvl: 1
  | bar

If you provide a list instead of a string, no shell will be used to interpret your command: the process and arguments will be sent directly to the system:

>>> wrap(["/bin/cat", "/tmp/should-not-exist-file-xxxx"])
Traceback (most recent call last):
ShellError: Wrapped command returned with unexpected errorlevel.
  command: ['/bin/cat', '/should-not-exist-file-xxxx']
  errlvl: 1
  | /bin/cat: /tmp/should-not-exist-file-xxxx: No such file or directory


  • that a wrap(..) command will strip output (remove whitespaces and newlines from the beginning and the ending of the output). If you don’t want this to happen, you can provide strip=False.

    >>> from import wrap
    >>> print("[%s]" % wrap('echo "  foo   "'))
    >>> print("[%s]" % wrap('echo "  foo   "', strip=False))
    [  foo   ]
  • wrap(..) support nice exception message even when handling multi-line content (typically used for shell scripting):

    >>> from import wrap
    >>> print(wrap('''
    ...    if [ "bar" ]; then
    ...       echo "foo"
    ...       exit 3
    ...    else
    ...       exit 4
    ...    fi
    ... '''))
    Traceback (most recent call last):
    ShellError: Wrapped command returned with unexpected errorlevel.
      |    if [ "bar" ]; then
      |       echo "foo"
      |       exit 3
      |    else
      |       exit 4
      |    fi
      errlvl: 3
      | foo


If you would rather want to get all information from the command, you can use cmd:

>>> from import cmd

>>> cmd('test "$HELLO" && echo "foo" || { echo "bar" ; false ; }')
ShellOutput(out=...'bar\n', err=...'', errlvl=1)

So, notice it doesn’t cast any exception, but outputs a named tuple.

cmd(..) also support handling a list of arguments instead of a command string if you want to bypass shell interpretation:

>>> cmd(['/bin/cat', '/file-does-not-exist-xxxx'])
ShellOutput(out=...'', err=...'...', errlvl=1)


Any suggestion or issue is welcome. Push request are very welcome, please check out the guidelines.

Push Request Guidelines

You can send any code. I’ll look at it and will integrate it myself in the code base and leave you as the author. This process can take time and it’ll take less time if you follow the following guidelines:

  • check your code with PEP8 or pylint. Try to stick to 80 columns wide.

  • separate your commits per smallest concern.

  • each commit should pass the tests (to allow easy bisect)

  • each functionality/bugfix commit should contain the code, tests, and doc.

  • prior minor commit with typographic or code cosmetic changes are very welcome. These should be tagged in their commit summary with !minor.

  • the commit message should follow gitchangelog rules (check the git log to get examples)

  • if the commit fixes an issue or finished the implementation of a feature, please mention it in the summary.

If you have some questions about guidelines which is not answered here, please check the current git log, you might find previous commit that would show you how to deal with your issue.


Copyright (c) 2018 Valentin Lab.

Licensed under the BSD License.


0.0.8 (2018-04-09)


  • Removing swrap(..) in favor of strip=True keyword argument of wrap(..). [Valentin Lab]

0.0.7 (2018-04-09)


  • Providing list of arguments to wrap, swrap, cmd allows to bypass shell. [Valentin Lab]

  • More docs about wrap(..)` and ``swrap(..) [Valentin Lab]


  • Fixed typo. [Valentin Lab]

0.0.6 (2015-03-12)


  • ShellError handles full output of failing shell command call. [Valentin Lab]


  • [sh] set_env wouldn’t properly set the environment variables. [Valentin Lab]

0.0.5 (2015-02-06)


  • Restructured to avoid package .tests. [Valentin Lab]

0.0.2 (2015-02-06)


  • Added doc on cmd command. [Valentin Lab]

  • Provide testing facilities. [Valentin Lab]

    • introduction of set_env

    • unittest base class BaseShTest

    • using a namedtuple for truple from cmd

0.0.1 (2014-05-13)

  • First import. [Valentin Lab]

Download files

Download the file for your platform. If you're not sure which to choose, learn more about installing packages.

Source Distribution (8.6 kB view hashes)

Uploaded source

Built Distribution (12.0 kB view hashes)

Uploaded py2 py3

Supported by

AWS AWS Cloud computing Datadog Datadog Monitoring Facebook / Instagram Facebook / Instagram PSF Sponsor Fastly Fastly CDN Google Google Object Storage and Download Analytics Huawei Huawei PSF Sponsor Microsoft Microsoft PSF Sponsor NVIDIA NVIDIA PSF Sponsor Pingdom Pingdom Monitoring Salesforce Salesforce PSF Sponsor Sentry Sentry Error logging StatusPage StatusPage Status page