Which shell do I use? (mac)

get_shell()

# get_shell
#
# This will work when called in a function and in functions calling functions etc.
# The function uses ps(1) to find out which shell is used. The following table 
# shows the shell names used to distinguse them (mac osx).
#
# Shells:	bash | bash | sh | ksh | csh | tcsh | zsh |
# Shells (ps):	bash |-bash | sh | ksh | -sh | -csh | zsh |
#
get_shell() { 	
	ps -o command | grep -P "^(?:-bash|bash|sh|ksh|-sh|-csh|zsh)$" | tail -n 1
}