- /etc/rc or
Scripts or directories of scripts
to run at startup or when changing the run level.
See Section 2.3.1 for further
The user database, with fields giving the
username, real name, home directory, and other information
about each user. The format is documented in the
passwd manual page.
/etc/shadow is an
encrypted file the holds user passwords.
Floppy disk parameter table.
Describes what different floppy disk formats look
like. Used by setfdprm
. See the
setfdprm manual page for more
Lists the filesystems mounted automatically
at startup by the mount -a command (in
/etc/rc or equivalent startup file).
Under Linux, also contains information about swap areas used
automatically by swapon -a
. See Section 5.10.7 and the mount
manual page for more information. Also
fstab usually has its own manual page in
Similar to /etc/passwd,
but describes groups instead of users. See the
group manual page in section 5 for more
Configuration file for
Output by getty
the login prompt. Usually contains a short description or
welcoming message to the system. The contents are up to
the system administrator.
The configuration file
for file. Contains the
descriptions of various file formats based on
which file guesses the type of
the file. See the magic and
file manual pages for more information.
The message of the day, automatically
output after a successful login. Contents are up to the
system administrator. Often used for getting information
to every user, such as warnings about planned downtimes.
List of currently mounted filesystems.
Initially set up by the bootup scripts, and updated
automatically by the mount
command. Used when a list of mounted filesystems is
needed, e.g., by the df
Configuration file for the
login command. The
login.defs file usually has a manual
page in section 5.
intended for printers. However it uses different syntax.
The printcap has a manual page in
Files executed at login or startup time
by the Bourne, BASH
shells. These allow the system
administrator to set global defaults for all users. Users
can also create individual copies of these in their home
directory to personalize their environment.
See the manual pages for the respective shells.
Identifies secure terminals, i.e., the
terminals from which root is allowed to log in. Typically
only the virtual consoles are listed, so that it becomes
impossible (or at least harder) to gain superuser privileges
by breaking into a system over a modem or a network. Do not
allow root logins over a network. Prefer to log in as an
unprivileged user and use su
sudo to gain root
Lists trusted shells. The
chsh command allows users to change
their login shell only to shells listed in this file.
ftpd, is the server process that provides
FTP services for a machine, will check that the user's
shell is listed in /etc/shells
and will not let people log in unless the shell is
The terminal capability database.
Describes by what ``escape sequences'' various terminals
can be controlled. Programs are written so that instead
of directly outputting an escape sequence that only
works on a particular brand of terminal, they look up
the correct sequence to do whatever it is they want to
do in /etc/termcap. As a result
most programs work with most kinds of terminals.
See the termcap, curs_termcap,
and terminfo manual pages for