shells - pathnames of valid login shells
/etc/shells is a text file which contains the full pathnames of valid
login shells. This file is consulted by
chsh(1) and available to be
queried by other programs.
Be aware that there are programs which consult this file to find out if a user
is a normal user; for example, FTP daemons traditionally disallow access to
users with shells not included in this file.
/etc/shells
/etc/shells may contain the following paths:
/bin/sh
/bin/bash
/bin/csh
chsh(1),
getusershell(3),
pam_shells(8)