How to test what shell I am using in a terminal?

Question

How to check what shell I am using in a terminal? What is the shell I am using in MacOS?

Answer 1

Several ways, from most to least reliable (and most-to-least "heavy"):

1. ps -p$$ -ocmd=. (On Solaris, this may need to be fname instead of cmd.)
2. Check for $BASH_VERSION, $ZSH_VERSION, and other shell-specific variables.
3. Check $SHELL; this is a last resort, as it specifies your default shell and not necessarily the current shell.

Answer 2

I've found that the following works in the four shells I have installed on my system (bash, dash, zsh, csh):

$ ps -p $$

The following works on zsh, bash, and dash, but not on csh:

$ echo $0

Answer 3

A note about some lighter implementations (Android phones, busybox, etc.): ps doesn't always have support for the -p switch, but you can accomplish the search with a command like ps | grep $$.

Answer 4

As the question asks for the shell used and does not talk about the potential arguments passed to it, here is a way that avoid showing them:

$ ps -o comm= -p $$
ksh93 

Answer 5

This works too:

env | grep SHELL