A shell is nothing but a command that provides a text-only user interface (also known as “command line interface”) for Linux, MacOS, and Unix-like operating systems. Bash shell read commands such as ls, date and others typed into a terminal and then run them. That is the primary function of bash shell.

How do I fund out the default shell for a user?
Type the following command to find out the default shell for a user named vivek using the grep command and /etc/passwd file:
$ grep vivek /etc/passwd
vivek:x:1005:1005:,,,:/home/vivek:/bin/zsh
OR
$ ps -p $$
PID TTY TIME CMD
14314 pts/9 00:00:00 zsh
OR
$ echo $0
zsh
All of the above output indicates that the shell is zsh for user named vivek in Linux operating system.
How do I see what shells are available on my system?
Type the cat command as follows:
$ cat /etc/shells
Sample outputs:
How do I switch to a bash or different shell?
Type the name at the command line and then press the enter key. In this example, to change from any shell to the bash, type:
bash
How to change shells on a Linux or Unix-like systems?
You can change your default shell using the chsh (“change shell” ) command as follows. The syntax is:
chsh
chsh -s {shell-name-here}
chsh -s {shell-name-here} {user-name-here}
chsh -s /bin/bash
chsh -s /bin/bash vivek
You can find full path to your shell using the following command:
type -a bash
type -a zsh
type -a ksh
Please note that a normal user may only change the login shell for her own account. The superuser (root) may change the login shell for any account using the following syntax:
$ sudo chsh -s /bin/bash raj
getent passwd $USERNAME
will provide user’s shell as wellFirst command doesn’t show the result. 2nd, 3rd and yours command provided me the shell information. Also you can change $USERNAME variable with the user name desired.
I have a Linux system with AD authentication; chsh command does not work for my configuration. Is there any other way to change the default change? Thanks.
AD as in active directory? Are you using bash under Windows 10? Give us more info.