Execute a custom bash function within python

Question

This question is a simpler version of this question.

In simple terms, I have a custom bash function my_func defined on ~/.bash_profile and uses two more bash functions defined in the same environment.

Also, my_func accepts two arguments, let's say a and b. What my_func does is that it gets connected to a remote server and sends some files (these are determined by a and b).

If I type on the bash shell: . my_func a b everything works fine and I get some print statements on the screen.

However, if I include: subprocess.call(['#!/bin/bash . my_func a b'], shell=True) nothing seems to happen.

I tried to export all the bash functions that are used by my_func by including:

subprocess.call(['#!/bin/bash export -f my_func'], shell=True) and I did the same for the rest of the functions that are used by my_func.

EDIT:

If I use subprocess.call(['bash', '-c' ,'my_func a b], shell=True) the bash shell will change into bash-3.2$

hek2mgl · Accepted Answer · 2017-11-09 11:52:08Z

1

You need to export the function before you start the python program:

export -f my_func
python foo.py

Well, the above example might not work if the system's default shell (/bin/sh) is not bash. To circumvent this, you may use subprocess call like this:

$ function foo() { echo "bar" ; }
$ export -f foo
$ cat foo.py
import subprocess
subprocess.call(['bash', '-c', 'foo'])
$ python foo.py
bar

Alternative:

I would put the function into a lib file, let's say:

# /usr/share/my_lib/my_lib.sh

function my_func() {
    # do something
}

Then I would expose the function via a script in PATH:

#!/bin/bash
# /usr/local/bin/my_prog

source /usr/lib/my_lib/my_lib.sh
my_func "$1" "$2"

In Python you would just:

subprocess.call(['/usr/local/bin/my_prog', 'a', 'b'])

Btw: If you don't need that function somewhere else, you can just put it directly into /usr/local/bin/my_prog.

edited Nov 9, 2017 at 11:52

answered Nov 9, 2017 at 10:29

hek2mgl

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5 Comments

thanasissdr Over a year ago

Thanks for the answer. I tried to do that, but it didn't seem to have any effect.

hek2mgl Over a year ago

Look carefully at the example. I'm not using shell=True

thanasissdr Over a year ago

If I don't do that I do run into a lot of errors, like ssh: command not found, basename:commnand not found, rsync: command not found e.t.c. All these commands are included in the definition of my_func.

hek2mgl Over a year ago

Hard to reproduce without seeing the function. Stupid question, why don't you simply put that function into a script, let's say /usr/local/bin/my_script and just call that script? Wouldn't it be much simpler?

thanasissdr Over a year ago

Great, this seems to be less complex. Thanks.

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