update-shells - update the list of valid login shells
update-shells [options]
update-shells locates the shells provided by packages from /usr/share/debianutils/shells.d and updates /etc/shells with newly added or removed shells. To track changes made by the administrator, it consults a state file in /var/lib/shells.state .
Do not actually perform the changes to /etc/shells .
ROOT
Operate on a chroot at ROOT .
Print the shells that are being added or removed.
/etc/shells /var/lib/shells.state /usr/share/debianutils/shells.d