Skip to main content

Pythonic command runner

Project description

CommandLib is a pythonic wrapper around subprocess that lets you pass around command objects and daisy-chain:

  • Arguments
  • Paths
  • Other environment variables
  • Runtime directory
  • Other runtime properties (run in shell, conceal stdout/stderr, ignore error codes, etc.)

It is somewhat inspired by amoffat’s sh, Kenneth Reitz’s requests, jaraco’s path.py and SQLAlchemy.

To install:

$ pip install commandlib

Example:

>>> from commandlib import Command
>>> ls = Command("ls")
>>> ls("-t").in_dir("/").with_shell().run()
sys  tmp  run  dev  proc  etc  boot  sbin  root  vmlinuz  initrd.img  bin  lib  opt  vmlinuz.old  initrd.img.old  media  home  cdrom  lost+found  var  srv  usr  mnt

CommandPath example:

>>> from commandlib import CommandPath
>>> bin = CommandPath("/bin")
>>> bin.ls("-t").in_dir("/").run()
sys  tmp  run  dev  proc  etc  boot  sbin  root  vmlinuz  initrd.img  bin  lib  opt  vmlinuz.old  initrd.img.old  media  home  cdrom  lost+found  var  srv  usr  mnt

API

>>> from commandlib import Command, run

# Create command object
>>> py = Command("/usr/bin/python")

# Run with *additional* environment variable PYTHONPATH (*added* to global environment when command is run)
>>> py = py.with_env(PYTHONPATH="/home/user/pythondirectory")

# Run with additional path (appended to existing PATH environment variable when command is run)
>>> py = py.with_path("/home/user/bin")

# Run in specified directory (default is current directory)
>>> py = py.in_dir("/home/user/mydir")

# Run in shell
>>> py = py.with_shell()

# Suppress stderr
>>> py = py.silently() # Suppress stdout and stderr

# Finally run command explicitly with all of the above
>>> run(py)
>>> py.run() # alternative syntax

Why?

Commandlib is a library to make it easier to pass around immutable (sort of) command objects between different modules and classes and incrementally modify the command’s behavior in a readable way - adding environment variables, paths, etc.

  • call, check_call and Popen do not have the friendliest of APIs and code that uses them a lot can get ugly fast.
  • sh does a similar thing but has a lot of magic (e.g. overriding import).
  • envoy and sarge are more focused on chaining commands rather than arguments, environment variables, etc.

Advanced API

Add trailing arguments:

>>> from commandlib import Command, run
>>> manage = Command("/usr/bin/python", "manage.py").with_trailing_arguments("--settings", "local_settings.py").in_dir("projectdir")
>>> run(manage("runserver"))
[ Runs "/usr/bin/python manage.py runserver --settings local_settings.py" inside projectdir ]

Dynamically generate command bundles from directories with executables in them:

>>> from commandlib import CommandPath, Command, run
>>> postgres94 = CommandPath("/usr/lib/postgresql/9.4/bin/")
>>> run(postgres94.postgres)
[ Runs postgres ]

>>> run(postgres94.createdb)
[ Runs createdb ]

Use with path.py (or any other library where str(object) resolves to a string:

>>> from path import Path
>>> postgres94 = CommandPath(Path("/usr/lib/postgresql/9.4/bin/"))
>>> run(postgres94.postgres)

Project details


Download files

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

Filename, size & hash SHA256 hash help File type Python version Upload date
commandlib-0.3.5.tar.gz (6.9 kB) Copy SHA256 hash SHA256 Source None Oct 5, 2018

Supported by

Elastic Elastic Search Pingdom Pingdom Monitoring Google Google BigQuery Sentry Sentry Error logging AWS AWS Cloud computing DataDog DataDog Monitoring Fastly Fastly CDN SignalFx SignalFx Supporter DigiCert DigiCert EV certificate StatusPage StatusPage Status page