Python Shell Pipes

A simple way to access your shell commands in Python

The shpipes package uses subprocess.Popen to run commands in a shell easily from native Python.

    >>> from shpipes import Pipe
    # python --version
    >>> Pipe('python')('--version').getvalue()
    'Python 3.8.6\n'

Chaining pipes together

You can chain together your commands, passing output from one to the input of another, similar to shell pipes. You can use the bitwise inclusive or operator to chain Pipe instances together.

    # echo 1+1 | bc
    >>> (Pipe('echo')('1+1') | Pipe('bc')).getvalue()
    '2\n'
    # This also works
    >>> pipe = Pipe('echo')('1+1')
    >>> pipe |= Pipe('bc'))
    >>> pipe.getvalue()
    '2\n'

Loading commands from your PATH

Shell Pipes can also collect all executables from your PATH variable and gather them into a Commands instance so you can use the lib just like your native shell.

    >>> from shpipes import Commands
    >>> shell = Commands()
    # find . -type f | grep .py$ | wc -l
    >>> (shell.find('.', '-type', 'f') | shell.grep('.py$') | shell.wc('-l')).getvalue()
    '9\n'
    # this also works
    >>> pipe = shell.find('.', '-type', 'f')
    >>> pipe |= shell.grep('.py$')
    >>> pipe |= shell.wc('-l')
    >>> pipe.getvalue()
    '9\n'

Handling pipe arguments

When a Pipe is called, its arguments are directly passed to Popen so beware that strings must be quoted properly. You can use getvalue() to get the output from one pipe and then pass it as a command argument instead of input text. Pipes are only evaluated when getvalue() is called

    >>> license = shell.find('.', '-name', '"LICENSE"').getvalue()
    >>> shell.wc(license).getvalue()
    '  21  169 1069 ./LICENSE\n'

Shell by default

Since pipes run in a shell by default, environment variables evaluate automatically

    >>> pipe = shell.ps('-u $USER')
    >>> pipe |= shell.grep('python')
    >>> pipe |= shell.head('-1')

Configuration options

If you need to run a different shell or disable shell entirely, then you can pass options via environment variables or kwargs to Pipe

Overriding options in Pipe

You can override all options to Popen (except stdin/stdout) by passing arguments to Pipe By default Popen is run in shell mode with your default shell.

    >>> Pipe('ls', executable='/bin/zsh', cwd='/var', shell=False)

Set env SHPIPES_NO_SHELL=true

Sets shell=False in the call to Popen

Set env SHPIPES_SHELL=/bin/zsh

Changes the executable shell run by Popen