running multiple bash commands with subprocess

You have to use shell=True in subprocess and no shlex.split:

import subprocesscommand = "echo a; echo b"ret = subprocess.run(command, capture_output=True, shell=True)# before Python 3.7:# ret = subprocess.run(command, stdout=subprocess.PIPE, shell=True)print(ret.stdout.decode())

returns:

ab

I just stumbled on a situation where I needed to run a bunch of lines of bash code (not separated with semicolons) from within python. In this scenario the proposed solutions do not help. One approach would be to save a file and then run it with Popen, but it wasn't possible in my situation.

What I ended up doing is something like:

commands = '''echo "a"echo "b"echo "c"echo "d"'''process = subprocess.Popen('/bin/bash', stdin=subprocess.PIPE, stdout=subprocess.PIPE)out, err = process.communicate(commands)print out

So I first create the child bash process and after I tell it what to execute. This approach removes the limitations of passing the command directly to the Popen constructor.

Join commands with "&&".

os.system('echo a > outputa.txt && echo b > outputb.txt')