When a user logs in via telnet or at the console, or opens an xterm
window in X the users shell program will be run to interpret commands
entered. If a user does not have a valid shell program or has one that
does nothing (like /bin/false), then that user will not be able to
login. This can be useful when creating users who can only read and send
email.
Listed in this field are all the shells used by users on your system. You
may select one, or choose Other.. and enter the full path of the
shell in the text field below.
All Unix systems come with the Bourne shell (/bin/sh) and the
C Shell (/bin/csh). Other common and more user-friendly shells
are tcsh, zsh and bash.