$? variable in linux

$? Status of the previous process / command which ran on the shell

$ pwd
$ echo $? // returns 0 which means the previous command ran sucessfully

$ blahCommand
$echo $? // returns 1 which means the previous command failed

This is very handy to see the status of the process while working with Jenkins. You can see what was the status of the previous process and based on that you can continue.

terminal 15 process 3 bash 18 cli 6 exit code 1