ubuntu bash脚本未运行

Question

Below is my script and this script is design to work to check if "python3.6" process is running.

If it is not running then execute python code else exit 0.

I don't see any activity or process running of python from this bash script.

please help me to understand if i scripted something wrong.

Any help is greatly appreciated.

Thanking in advance.

#!/bin/bash

ps x |grep -v grep |grep -c "python3.6" 
if [ $? -eq 0 ]; then
bash -c "/home/ubuntu/anaconda3/bin/python3.6 /var/lib/pythoncode/main_progm.py >> /home/ubuntu/Logs.txt"
fi

# End of Script

Answer 1

if [ $? -eq 0 ]; then if [ $? -eq 0 ]; then means "If the last command exited without error". grep returns an error result when it can't find stuff; so your if says "If you found a Python process, run another Python process, otherwise never mind". So your code doesn't find the Python process, and so never launches one (mistakenly believing solitary life is no life at all).

You can change it in multiple ways. You can change -eq to -ne .

Or you don't even need to compare the exit code explicitly, because that's what if does. You could write:

if ps x | grep -v grep | grep -c python3.6
then
  # grep found stuff and exited with $? == 0
  echo Oops, still running
else
  # grep failed and exited with $? != 0
  echo Good to go, run it
fi

Or you can use that count that you produced:

pythoncount=$(ps x |grep -v grep |grep -c "python3.6")
if [ $pythoncount -eq 0 ]

Answer 2

Thank you all for your help & kind cooperation.

With comments suggestions, i did minor change & my bash is running fine.

Below is the code, i hope it will help somebody might step into similar situation.

thank you again.

#!/bin/bash

ps -x |grep -v grep |grep -c "python3.6" >/dev/null
if [ $? -ne 0 ]; then
bash -c "/home/ubuntu/anaconda3/bin/python3.6 /var/lib/pythoncode/main_progm.py >> /home/ubuntu/Logs.txt"
else
exit 0;
fi