file contains a list of valid shells
available on the system. A shell is a command line interpreter that reads user
input and executes commands. For each shell a single line should be present,
consisting of the shell's path, relative to root.
A hash mark (‘#’) indicates the beginning of a comment; subsequent
characters up to the end of the line are not interpreted by the routines which
search the file. Blank lines are also ignored.
will not let regular users change their default shell to one not listed in the
access to users who are not using one of the listed shells.
file format appeared in