This issue lacks a lot of information:

* What is your operating system (name and version)? On Linux, what is your Linux kernel version?
* Which Python version did you try?
* Which command are you running?
* Do you use a shell?
* Do you use bytes (default) or Unicode (universal_newlines=True or text=True)?
* Can you provide a minimum reproducer? I don't know how to use msg349894: cmd is not defined.

Attached 1.py uses 2 commands, appararently both use a shell:

* "find /usr/bin -type f 2>/dev/null"
* "objdump '%s'"

"objdump '%s'" is unsafe and can lead to shell injection: try to avoid the usage of a shell. Use subprocess.Popen directly, or an helper which doesn't use shell=True.