How to get the PID of a recently started process in Bash

command-line bash scripts

30,065

Solution 1

There are various ways:

Let the script write its pid itself. Include line echo $$ > /tmp/my.pid in your script.
Use pidof script_name
Use ps -ef | grep script_name | tr -s ' ' | cut -d ' ' -f2

Solution 2

You could use

pidof xxx_program

if that is the name of the process. (must be full process name how it was invoked, including any options or commandline paths)

30,065

Yuran Pereira

Updated on September 18, 2022

Comments

Yuran Pereira over 1 year
I have a bash script file that contains the following code script.sh
```
./xxx_program arguments &
PID=$!
echo $PID
kill -INT $PID
```
what I am trying to do is to start a program "xxx_program" and then store its PID on the $PID variable. But instead I keep getting the PID of "bash" itself instead of the program I open which causes the kill -INT $PID to just quit the script.sh while the xxx_program remains running. Note the xxx_program opens but I just get the wrong PID.

I would like to know if there's a way to get the PID of xxx_program? Thanks in advance
- muru almost 7 years
  
  Show us your actual script.
- Yuran Pereira almost 7 years
  
  @muru the other parts of the script that I did not show are really irrelevant to solving the problem. The way I wrote it up, is the same way I have it structured on my original script with the exception of "xxx_program" this is because I will not be using this for only one specific program.
- muru almost 7 years
  
  Since $! works fine for getting the PID of the last backgrounded command and has worked fine for decades, it is certainly a better option than pidof, pgrep or anything else. If it doesn't work for you, then no, the script is not the same way you wrote it.
- Yuran Pereira almost 7 years
  
  @muru well, whatever you may think. Anyhow it's solved now. Perhaps pidof even though not the quickest, is somehow more reliable?... Anyway, thanks for the help.
- muru almost 7 years
  
  As you say, "whatever you may think".
- Yuran Pereira almost 7 years
  
  @muru PS: not trying to be rude tho. It just is what it is :p Peace
Yuran Pereira almost 7 years

Thanks a lot this worked great. "pidof" is definitely a better option compared to what I was doing
Hiran Chaudhuri about 2 years

The last line delivers two results: The pid of the grep is part of it.