how to get PID and State of certain Processes

Question

I have created a basic shell script that simply counts down from 1000. This is just for testing but could be any application/process.

##filename:test.sh##

#!/bin/bash
i=1000; while [ $i -gt 0 ]; do echo $i; i=`expr $i - 1`; sleep 1; done

Which I start running thus:

sh test.sh

I now need to get: a) the pid of that script, b) the state of that script

If I do

pidof sh test.sh 

I get multiple results though.

Running

ps aux | grep test.sh 

I get multiple entries including some that are Terminated (state=T) and one that is grep test.sh. How can I restrict the pidof to just the one(s) I need (assume it is just the one instance that is running)

I also need the state. I tried running:

ps aux | grep test.sh | ps -o stat --no-headers

but that didn't work. I get the state, but for multiple items

Answer 1

pidof -x test.sh should give you what you need to get the PID.

From the man page,

-x Scripts too - this causes the program to also return process id's of shells running the named scripts.

Here's my test,

tony@trinity:~$ ls -l testit.sh
-rwxr-xr-x 1 tony tony 83 Jan  5 14:53 testit.sh
tony@trinity:~$ ./testit.sh
1000
999
998
997

meanwhile

tony@trinity:~$ ps -ef | grep testit.sh
tony      4233 20244  0 14:58 pts/5    00:00:00 /bin/bash ./testit.sh
tony      4295  3215  0 14:58 pts/6    00:00:00 grep --color=auto testit.sh

and then

tony@trinity:~$ pidof -x testit.sh
4233

Your later query is a common issue, one solution is,

ps aux | grep test.sh | grep -v grep

which should give you only a single line (assuming test.sh is unique).

And lastly, in your final command, you're not just passing a single PID, you're passing a whole line of text, and that's not how ps expects to be given a PID anyway (it expects the PID after -p).

For example,

tony@trinity:~$ ps aux | grep testit.sh
tony      4233  0.1  0.0   4288  1276 pts/5    S+   14:58   0:00 /bin/bash ./testit.sh
tony      5728  0.0  0.0   3476   760 pts/6    S+   15:04   0:00 grep --color=auto testit.sh

So we need to grep out the grep, and then only return the pid.

tony@trinity:~$ ps aux | grep testit.sh | grep -v grep | awk '{print $2}'
4233

then,

tony@trinity:~$ ps -o stat --no-headers -p $(ps aux | grep testit.sh | grep -v grep | awk '{print $2}')
S+

There are probably plenty of less convoluted ways to get there, but I wanted to show the progress.