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bashsedtrim

Trim output of running program

I have a program that when it runs, outputs hundreds of lines starting with "Info:" and a few lines that have useful output. To make things easier, I have created a simple python and bash combination script to emulate the issue I'm having:

wait_2sec.py:

import time

print("Hello!")
time.sleep(2)
print("Goodbye!")

I am attempting to trim my output by running:

 python wait_2sec.py | sed '/Goodbye/d'

However, sed does not output Hello! until after the python script has finished. I don't know whether the pipe waits until after the program is finished to begin running the sed command, or if the sed command is the hangup. I am open to using another command to trim output if sed does not work for this use-case.

Solution

  • You can try to run your script using the following command:

    unbuffer python wait_2sec.py | sed '/Goodbye/d'

    Refrence: https://unix.stackexchange.com/a/200413