Find out who I was before I had switched users in Linux?

Question

$ whoami
a

$ su b
Password: ...

$ whoami
b

Is there a whowasi command? Some way to find out that I was user a before I had become user b?

Answer 1

• Technically, you didn't switch users; you opened a separate shell process as b. You can suspend it with suspend, use whoami, then return with fg.

• You can check the owner of the parent process with ps -f $PPID.

• Use who -m or who am i to see the user you originally logged in as. (This is different from the above two methods because it always returns the same user despite how many times you run su.)

• Use ps -f to see all processes running on the current tty, including their owners.

Answer 2

You can do a who to see what user is the original owner of the session