how to check if already logged in perforce from command line

Question

I want command to check if I am already logged in perforce, which returns 0 if I am logged in, otherwise some non-zero value to represent error. how to achieve this from command line?

Answer 1

p4 help login says:

p4 login [-a -p] [-h <host>] [user]
p4 login [-s]

[...]

The -s flag displays the status of the current ticket (if there is one).

Additionally, empirical testing shows that running p4 login -s while logged in returns an exit code of 0, and running it while not logged in returns an exit code of 1.