I'm using Ubuntu 16.04 LTS and I try to grep the PID of some process. Here is what I've done in terminal:
# ps aux | grep xorg | grep -v 'grep' | awk '{print $2}'
After executing the command above, I get the result:
2367
However, then I create a script named t.sh as below:
#!/bin/bash
a=$(ps aux | grep $1 | grep -v 'grep' | awk '{print $2}')
echo $a
I execute it: ./t.sh xorg
But I get: 2367 57270 57271
I have no idea where the two numbers come from. I only know that the two numbers always change when I execute ./t.sh xorg and they are adjacent (n and n + 1).
I just found another thing:
If I fix xorg into the script, instead of passing parameter, the two numbers will disappear.
#!/bin/bash
a=$(ps aux | grep xorg | grep -v 'grep' | awk '{print $2}')
echo $a
This script will work as expected.
Duplicated question
Different results between ps aux and `ps aux` inside a script
After reading the post, I still don't know what I can do to solve my problem.
