Get the last(latest) process pid in linux

If you want the process ID of the most recently executed background command you can use the ! variable. For example:

 > gvim text.txt & > echo $! 2842

Update: Thanks to William for the hint about awk.
Pre-condition: The process has still to be running.

I am not an UNIX expert, but I thought about the following approach:

ps aux --sort +start_time | tail -n 4 | awk 'NR==1{print $2}'

ps will list all processes and we are going to sort them by start_time. Afterwards we are going to take the fourth from the last line [0] of the output and awk will return the pid found in the second field.

root@unix ~ % sleep 10 &[1] 3009root@unix ~ % ps aux --sort +start_time | tail -n 4 | awk 'NR==1{print $2 " " $11}'3009 sleeproot@unix ~ %

[0] The fourth line because there are three piped commands in my commandline.

Get PID:

#!/bin/bashmy-app & echo $!

Save PID in variable:

#!/bin/bashmy-app & export APP_PID=$!

Save all instances PID in text file:

#!/bin/bashmy-app & echo $! >>/tmp/my-app.pid

Save output, errors and PID in separated files:

#!/bin/bashmy-app >/tmp/my-app.log 2>/tmp/my-app.error.log & echo $! >>/tmp/my-app.pidecho "my-app PID's: $(cat /tmp/my-app.pid)"