There are many shells which are not coming by default in our operating system. So, that time we need to install it externally by downloading rpm package for Linux, deb package for Solaris, do apt-get for Ubuntu etc. But when we install this shell and somehow it is not working then we need configure it with following steps:
Install shell’s rpm, deb etc. package into operating system.
Now try to access that shell or try to switch that shell if it is not working then run following steps.
Check configuration file /etc/shells and make entry for that shell like /bin/csh/ or /usr/bin/es or /usr/bin/rc or /bin/rbash etc. If entry is already present then don’t do anything.
But this step has to execute after installation only.
Run following command after making entry in /etc/shells.
root@hello:~/home/test# add-shell shell-name