import subprocess # Create a Popen class instance and run command `cat` in a seperate process proc = subprocess.Popen( ['cat', '-'], # Also we're going to send come data into command's standard input, so # we indicate that it would be PIPE stdin=subprocess.PIPE, # And we shall read output as a stream stdout=subprocess.PIPE ) # Let us start communication stdout_value = proc.communicate('string to read') print stdout_value