1. ► You cannot use a shell not listed in /etc/shells.
2. ► /etc/password stores user password in plain text.
3. ► libtermcap makes use of /etc/termcap.
4. ► PATH variable is common across shells.
5. ► An user cannot change his/her finger information.
6. ► csh is an extended version of tcsh.
7. ► ls --color is not a POSIX compliant option.
8. ► ksh, zsh and bash all extend sh.
9. ► set and export do identical functions.
10. ► Login shells can only be started by the system at login time.