passing data to subprocess.check_output

Question

I want to invoke a script, piping the contents of a string to its stdin and retrieving its stdout.

I don\'t want to touch the real filesystem so I can\'t create real

Answer 1

In Python 3.4 and newer, you can use the input keyword parameter to send input via STDIN when using subprocess.check_output()

Quoting from the standard library documentation for subprocess.check_output():

The input argument is passed to Popen.communicate() and thus to the subprocess’s stdin. If used it must be a byte sequence, or a string if universal_newlines=True. When used, the internal Popen object is automatically created with stdin=PIPE, and the stdin argument may not be used as well.

Example:

>>> subprocess.check_output(["sed", "-e", "s/foo/bar/"],
...                         input=b"when in the course of fooman events\n")
b'when in the course of barman events\n'
>>> 
>>> # To send and receive strings instead of bytes,
>>> # pass in universal_newlines=True
>>> subprocess.check_output(["sed", "-e", "s/foo/bar/"],
...                         universal_newlines=True,
...                         input="when in the course of fooman events\n")
'when in the course of barman events\n'