Shell on Linux operating system is command-line interpreter that provides a user interface. Using it the user can execute the commands on the server.
In simple terms shell means any program that users employ to type commands.
You can check the Shell you are currently logged in with as follows
If you wish to change the current login Shell of the user you can use the command chsh.
To list available shells, you can use below command
To change the shell of the user you can use the command as follows
chsh shell ( To be assigned ) username
Like in the example below if we wish to enable jail shell access to the cpanel user test we can use the below command
chsh /usr/local/cpanel/bin/jailshell test