How can I tell which Unix shell I am using? [duplicate]

Question

Is there an easy way by which I can tell which type of Unix shell I am in?

A command that shows whether I am in a Bash, C shell, KornShell (ksh), tcsh, or Z shell (zsh)?

E.g.,

whatshellisthis

Answer 1

Try:

echo $0 

This often works across a range of shells.

Answer 2

Mac

ps    PID TTY           TIME CMD   223 ttys000    0:00.33 -bash 

OpenBSD

ps    PID TT  STAT       TIME COMMAND 20038 p0  Ss      0:00.01 -ksh (ksh) 22251 p0  R+      0:00.00 ps 

Or just echo $SHELL.