flask - Using Python subprocess doesn't work, but calling directly in the shell does -

i'm trying run subprocess flask route, 500 error. works when run directly shell. why isn't working?

import subprocess flask import flask app = flask(__name__)  @app.route('/status/<vmid>') def status(vmid):     cmd = "/usr/bin/virsh list --all | grep kvm%s | awk {'print $3'}" % vmid     p = subprocess.popen(cmd, stdout = subprocess.pipe, stderr=subprocess.pipe, stdin=subprocess.pipe)     out,err = p.communicate()     return out  if __name__ == '__main__':     app.run(host='0.0.0.0') 

it raises 500 error when run through flask:

root@nc2-kvm:~# python status.py  * running on http://0.0.0.0:5000/ (press ctrl+c quit) (500 error) 

it works when run directly in shell:

root@nc2-kvm:~# virsh list --all | grep kvm180 | awk {'print $3'} running 

take @

https://docs.python.org/2/library/subprocess.html

for subprocess.call work in form you're using, need set shell argument true. make sure works, try subprocess.call in python repl first.