Checking Subprocesses in python

Question

I'm trying to run one python program from another using subprocess . Here's the function I've got so far:

def runProcess(exe):
p = subprocess.Popen(exe, stdout=subprocess.PIPE, stderr=subprocess.STDOUT)
while(True):
  retcode = p.poll() #returns None while subprocess is running
  line = p.stdout.readline()
  yield line
  if(retcode is not None):
    break

then i run:

for line in runProcess('python myotherprogram.py'): print line

but I get an OS error: no such file , but it doesn't tell me what file doesn't exist. It's baffling. Any suggestions? I can use the runProcess function for normal terminal commands, such as ls .

Answer 1

What doesn't exist is a single executable named python myotherprogram.py . To specify arguments, you need to provide a list consisting of the command and its argument, such as with runProcess(["python", "myotherprogram.py"]) , or specify shell=True to the Popen constructor.

The relevant quote from the documentation :

args should be a sequence of program arguments or else a single string. By default, the program to execute is the first item in args if args is a sequence. If args is a string, the interpretation is platform-dependent and described below. See the shell and executable arguments for additional differences from the default behavior. Unless otherwise stated, it is recommended to pass args as a sequence.

On Unix, if args is a string, the string is interpreted as the name or path of the program to execute. However, this can only be done if not passing arguments to the program.