Command works in shell but not in subprocess

I'm trying to run a command using the python subprocess package. I've added the path to the compiled executable to my PATH on an Ubuntu machine.

When I do this, it works:

myexecutable input_file output_file 

When I do this, it works:

import subprocess import shlex cmd = '/path/to/my/myexecutable input_file output_file' subprocess.Popen(shlex.split(cmd)) 

Here's the kicker. When I do this, it doesn't work:

import subprocess import shlex cmd = 'myexecutable input_file output_file' subprocess.Popen(shlex.split(cmd)) 

It gives me:

OSError Traceback (most recent call last) <ipython-input-4-8f5c3da8b0a3> in <module>() ----> 1 subprocess.call(shlex.split(cmd)) /home/me/miniconda3/envs/mypy2/lib/python2.7/subprocess.pyc in call(*popenargs, **kwargs) 170 retcode = call(["ls", "-l"]) 171 """ --> 172 return Popen(*popenargs, **kwargs).wait() 173 174 /home/me/miniconda3/envs/mypy2/lib/python2.7/subprocess.pyc in __init__(self, args, bufsize, executable, stdin, stdout, stderr, preexec_fn, close_fds, shell, cwd, env, universal_newlines, startupinfo, creationflags) 392 p2cread, p2cwrite, 393 c2pread, c2pwrite, --> 394 errread, errwrite) 395 except Exception: 396 # Preserve original exception in case os.close raises. /home/me/miniconda3/envs/mypy2/lib/python2.7/subprocess.pyc in _execute_child(self, args, executable, preexec_fn, close_fds, cwd, env, universal_newlines, startupinfo, creationflags, shell, to_close, p2cread, p2cwrite, c2pread, c2pwrite, errread, errwrite) 1045 raise 1046 child_exception = pickle.loads(data) -> 1047 raise child_exception 1048 1049 OSError: [Errno 2] No such file or directory 

What gives?