Running shell commands sequentially in one shell with subprocess

Question

I am having difficulties running a series of sequential commands using the subprocess module, i need to do this so a python program can call in an installation of a cv virtualenv and then run another python program (that needs to be run within the virtualenv)

This is the command string i run from terminal, you can see it contains multiple commands that run in sequence until the creation of the cv virtual env:

sudo pip install virtualenv virtualenvwrapper && sudo rm -rf ~/.cache/pip && export WORKON_HOME=$HOME/.virtualenvs && source /usr/local/bin/virtualenvwrapper.sh && source ~/.bashrc && mkvirtualenv cv

Running this in the terminal returns me something like this:

(cv) name@computer:~$

from that i can run my python scripts that need the openCV

my code so far is this:

from subprocess import Popen, PIPE, STDOUT cmd1 = 'sudo pip install virtualenv virtualenvwrapper' cmd2 = 'sudo rm -rf ~/.cache/pip' cmd3 = 'export WORKON_HOME=$HOME/.virtualenvs' cmd4 = 'source /usr/local/bin/virtualenvwrapper.sh' cmd5 = 'source ~/.bashrc' cmd6 = 'mkvirtualenv cv' cmd7 = 'cd /script path' cmd8 = 'python novo.py' final = Popen("{}; {}; {}; {}; {}; {}; {}; {}".format(cmd1, cmd2,cmd3, cmd4, cmd5, cmd6, cmd7, cmd8), shell=True, stdin=PIPE, stdout=PIPE, stderr=STDOUT, close_fds=True) stdout, nothing = final.communicate() log = open('log', 'w') log.write(stdout) log.close()

And the errors in log look like this:

/bin/sh: 1: source: not found /bin/sh: 1: source: not found /bin/sh: 1: mkvirtualenv: not found

How can i achieve a terminal like execution ? again, sequence is crucial.

Community · Accepted Answer · 2017-05-23 12:07:57Z

/bin/sh: 1: source: not found

shell=True uses /bin/sh by default. source shell builtin hints at bash. Pass executable='/bin/bash'.

btw, you could use a multiline string literal:

#!/usr/bin/env python3 import sys from subprocess import check_call, DEVNULL, STDOUT with open('log', 'wb', 0) as file: check_call("""set -e -x {python} -mpip install --user virtualenv virtualenvwrapper rm -rf ~/.cache/pip export WORKON_HOME=$HOME/.virtualenvs source /path/to/virtualenvwrapper.sh source ~/.bashrc mkvirtualenv cv cd /script path {python} novo.py """.format(python=sys.executable), shell=True, executable='/bin/bash', stdin=DEVNULL, stdout=file, stderr=STDOUT, close_fds=True)

Or save the command into a separate bash script and run the script instead.

DEVNULL is Python 3 feature—it is easy to emulate it on Python 2 too: DEVNULL = open(os.devnull, 'r+b', 0).

Hello J.F. Sebastian, thank you for your answer, i changed the code on my python script as you suggested, but now when i execute it gives an error "File "programa.py", line 3, in <module> from subprocess import check_call, DEVNULL, STDOUT ImportError: cannot import name DEVNULL" i am really new to this kind of operations, my knowledge stays on python and opencv, dont know how to properly work with this kind of calls and bash files.
i dont really understand how shebangs work but i changed it to pyhton2, it returns a 'CalledProcessError', you can check out the code and error on this image if it not too much trouble postimg.org/image/f6dfdaucr
My answer fixes one issue: source: not found. If you have another issue; you should ask it as a separate question.

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