diff -up src/sage/interfaces/ecm.py.orig src/sage/interfaces/ecm.py --- src/sage/interfaces/ecm.py.orig 2019-06-26 14:41:04.000000000 -0600 +++ src/sage/interfaces/ecm.py 2019-09-04 09:29:09.529723744 -0600 @@ -39,7 +39,7 @@ from __future__ import print_function from six import iteritems, PY2 -import os +import subprocess import re from sage.structure.sage_object import SageObject @@ -256,7 +256,7 @@ class ECM(SageObject): """ print("Enter numbers to run ECM on them.") print("Press control-C to exit.") - os.system(self._cmd) + subprocess.call(self._cmd) # Recommended settings from # http://www.mersennewiki.org/index.php/Elliptic_Curve_Method