Pythonic command runner
CommandLib is a pythonic wrapper around subprocess that lets you pass around command objects and daisy-chain:
- 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.
$ pip install commandlib
>>> 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
>>> 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
>>> 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
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.
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)
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