Find the current shell
There are a few ways to determine the current shell
echo $0
ps -p $$
echo $SHELL
List available shells
To list available login shells :
cat /etc/shells
Example:
$ cat /etc/shells
# /etc/shells: valid login shells
/bin/sh
/bin/dash
/bin/bash
/bin/rbash
Change the shell
To change the current bash run these commands
export SHELL=/bin/bash
exec /bin/bash
to change the bash that opens on startup edit .profile and add those lines