subprocess.run only accepting first argument

Question

Using Python 3.10.6
trying to pass an argument to a command line opened via subprocess.run, I’ve tried toggling shell=True/False, as well as passing the second argument with the input variable, no luck. here is the relevant code:

cmds = (['cmd','echo hello'])
cmd_result = subprocess.run(cmds, shell=False, check=True,
                            stdin=subprocess.PIPE,
                            stdout=subprocess.PIPE,
                            stderr=subprocess.PIPE,
                            universal_newlines=True )
print(cmd_result.args)

[‘cmd’, ‘echo hello’]

print(cmd_result.stdout)

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So it seems to recognize both the arguments, its just not doing anything with the second one. Any guidance is appreciated

Asked By: echocosm

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Source

Answer 1

If you run the command

cmd echo hello

from the CMD prompt, you do not get an echoed output of hello.

To run a command string, you need to add either /C or /K. The first runs a command string and exits, the second runs a command string and stays open. Without either of these flags, the command string is ignored.

Instead, try:

cmd /C echo hello

Adding this to your subprocess command, you get:

cmds = (['cmd', '/C', 'echo', 'hello'])
cmd_result = subprocess.run(cmds, shell=False, check=True,
                            stdin=subprocess.PIPE,
                            stdout=subprocess.PIPE,
                            stderr=subprocess.PIPE,
                            universal_newlines=True )
print(cmd_result.stdout)
# prints:
hello

Answered By: James

subprocess.run only accepting first argument

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