In my previous experiences, I've had success using subprocess.Popen to wrap binaries with a Python script and customize arguments. However, when developing another wrapper recently, I encountered an issue.
Here's the snippet of code I'm working with:
print command
p = subprocess.Popen(command, shell=True)
result = p.communicate()[0]
print vars(p)
return result
After executing this code, the output is as follows:
/usr/bin/sh /tmp/run/launch.sh
{'_child_created': True, 'returncode': 0, 'stdout': None, 'stdin': None, 'pid': 21650, 'stderr': None, 'universal_newlines': False}
The objective here is to create a shell script that sets up everything required and then runs it. While I'd prefer to use actual Python code, the launch.sh file calls third-party shell scripts that I don't want to replicate (despite my attempts to get a Python API for them for over a year).
The issue at hand includes:
- The shell script doesn't execute as expected (it should spawn a process and output something)
- No Python exception is raised
- There are no indications of errors in the
pobject
I also tried using check_call without any luck.
I'm stuck on what steps to take next, and would appreciate any guidance on where I may have made mistakes or how to resolve the situation.
EDIT:
- I'm running this on Linux using sh
- The shell is necessary for variable substitution in the invoked scripts
EDIT 2:
Following a suggestion from badp, I made some adjustments to the code and included
subprocess.Popen('ps', shell=True).communicate()
Right after the line where the process is created, here's the output:
/usr/bin/sh /tmp/run/launch.sh
PID TTY TIME CMD
29978 pts/0 00:00:01 zsh
1178 pts/0 00:00:01 python
1180 pts/0 00:00:00 sh <defunct>
1181 pts/0 00:00:00 ps
None
It appears that the process is launched (even though it shows <defunct>), and there seems to be an issue with passing parameters in as well.
Thank you.