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|
<!DOCTYPE HTML PUBLIC "-//Norman Walsh//DTD DocBook HTML 1.0//EN">
<HTML
><HEAD
><TITLE
>The /etc directory</TITLE
><META
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>The Linux System Administrators' Guide</TH
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><A
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><HR
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><DIV
CLASS="SECT1"
><H1
CLASS="SECT1"
><A
NAME="AEN338"
>The <TT
CLASS="FILENAME"
>/etc</TT
> directory</A
></H1
><P
>The <TT
CLASS="FILENAME"
>/etc</TT
> directory contains a lot
of files. Some of them are described below. For others, you
should determine which program they belong to and read the manual
page for that program. Many networking configuration files are
in <TT
CLASS="FILENAME"
>/etc</TT
> as well, and are described in the
<I
CLASS="CITETITLE"
>Networking Administrators' Guide</I
>.
<DIV
CLASS="GLOSSLIST"
><DL
><DT
><B
><TT
CLASS="FILENAME"
>/etc/rc</TT
> or <TT
CLASS="FILENAME"
>/etc/rc.d</TT
> or <TT
CLASS="FILENAME"
>/etc/rc?.d</TT
></B
></DT
><DD
><P
>Scripts or directories of scripts
to run at startup or when changing the run level.
See the chapter on <B
CLASS="COMMAND"
>init</B
> for further
information. </P
></DD
><DT
><B
><TT
CLASS="FILENAME"
>/etc/passwd</TT
></B
></DT
><DD
><P
>The user database, with fields giving
the username, real name, home directory, encrypted
password, and other information about each user.
The format is documented in the \man{passwd} manual page.
</P
></DD
><DT
><B
><TT
CLASS="FILENAME"
>/etc/fdprm</TT
></B
></DT
><DD
><P
>Floppy disk parameter table.
Describes what different floppy disk formats look
like. Used by <B
CLASS="COMMAND"
>setfdprm</B
>. See the
<B
CLASS="COMMAND"
>setfdprm</B
> manual page for more
information. </P
></DD
><DT
><B
><TT
CLASS="FILENAME"
>/etc/fstab</TT
></B
></DT
><DD
><P
>Lists the filesystems mounted
automatically at startup by the <B
CLASS="COMMAND"
>mount
-a</B
> command (in <TT
CLASS="FILENAME"
>/etc/rc</TT
>
or equivalent startup file). Under Linux, also contains
information about swap areas used automatically by
<B
CLASS="COMMAND"
>swapon -a</B
>. See <A
HREF="x1029.html#MOUNT-AND-UMOUNT"
>the section called <I
>Mounting and unmounting</I
> in Chapter 4</A
> and the
<B
CLASS="COMMAND"
>mount</B
> manual page for more information.
</P
></DD
><DT
><B
><TT
CLASS="FILENAME"
>/etc/group</TT
></B
></DT
><DD
><P
>Similar to
<TT
CLASS="FILENAME"
>/etc/passwd</TT
>, but
describes groups instead of users. See the
<B
CLASS="COMMAND"
>group</B
> manual page for more information.
</P
></DD
><DT
><B
><TT
CLASS="FILENAME"
>/etc/inittab</TT
></B
></DT
><DD
><P
>Configuration file for
<B
CLASS="COMMAND"
>init</B
>. </P
></DD
><DT
><B
><TT
CLASS="FILENAME"
>/etc/issue</TT
></B
></DT
><DD
><P
>Output by <B
CLASS="COMMAND"
>getty</B
> before
the login prompt. Usually contains a short description or
welcoming message to the system. The contents are up to
the system administrator. </P
></DD
><DT
><B
><TT
CLASS="FILENAME"
>/etc/magic</TT
></B
></DT
><DD
><P
>The configuration file
for <B
CLASS="COMMAND"
>file</B
>. Contains the
descriptions of various file formats based on
which <B
CLASS="COMMAND"
>file</B
> guesses the type of
the file. See the <TT
CLASS="FILENAME"
>magic</TT
> and
<B
CLASS="COMMAND"
>file</B
> manual pages for more information.
</P
></DD
><DT
><B
><TT
CLASS="FILENAME"
>/etc/motd</TT
></B
></DT
><DD
><P
>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.
</P
></DD
><DT
><B
><TT
CLASS="FILENAME"
>/etc/mtab</TT
></B
></DT
><DD
><P
>List of currently mounted filesystems.
Initially set up by the bootup scripts, and updated
automatically by the <B
CLASS="COMMAND"
>mount</B
>
command. Used when a list of mounted filesystems is
needed, e.g., by the <B
CLASS="COMMAND"
>df</B
> command.
</P
></DD
><DT
><B
><TT
CLASS="FILENAME"
>/etc/shadow</TT
></B
></DT
><DD
><P
>Shadow password file on systems
with shadow password software installed.
Shadow passwords move the encrypted password
from <TT
CLASS="FILENAME"
>/etc/passwd</TT
> into
<TT
CLASS="FILENAME"
>/etc/shadow</TT
>; the latter is not
readable by anyone except root. This makes it harder
to crack passwords. </P
></DD
><DT
><B
><TT
CLASS="FILENAME"
>/etc/login.defs</TT
></B
></DT
><DD
><P
>Configuration file for
the <B
CLASS="COMMAND"
>login</B
> command.
</P
></DD
><DT
><B
><TT
CLASS="FILENAME"
>/etc/printcap</TT
></B
></DT
><DD
><P
>Like <TT
CLASS="FILENAME"
>/etc/termcap</TT
>,
but intended for printers. Different syntax.
</P
></DD
><DT
><B
><TT
CLASS="FILENAME"
>/etc/profile</TT
>, <TT
CLASS="FILENAME"
>/etc/csh.login</TT
>, <TT
CLASS="FILENAME"
>/etc/csh.cshrc</TT
></B
></DT
><DD
><P
>Files executed at login or startup time
by the Bourne or C shells. These allow the system
administrator to set global defaults for all users.
See the manual pages for the respective shells.
</P
></DD
><DT
><B
><TT
CLASS="FILENAME"
>/etc/securetty</TT
></B
></DT
><DD
><P
>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. </P
></DD
><DT
><B
><TT
CLASS="FILENAME"
>/etc/shells</TT
></B
></DT
><DD
><P
>Lists trusted shells. The
<B
CLASS="COMMAND"
>chsh</B
> command allows users to change
their login shell only to shells listed in this file.
<B
CLASS="COMMAND"
>ftpd</B
>, the server process that provides
FTP services for a machine, will check that the user's
shell is listed in <TT
CLASS="FILENAME"
>/etc/shells</TT
>
and will not let people log in unles the shell is
listed there. </P
></DD
><DT
><B
><TT
CLASS="FILENAME"
>/etc/termcap</TT
></B
></DT
><DD
><P
>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 <TT
CLASS="FILENAME"
>/etc/termcap</TT
>. As a result
most programs work with most kinds of terminals.
See the <TT
CLASS="FILENAME"
>termcap</TT
>, curs_termcap,
and <TT
CLASS="FILENAME"
>terminfo</TT
> manual pages for
more information. </P
></DD
></DL
></DIV
>
</P
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>Prev</A
></TD
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></TD
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></TD
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><TR
><TD
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>The root filesystem</TD
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VALIGN="top"
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HREF="c212.html"
>Up</A
></TD
><TD
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ALIGN="right"
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>The <TT
CLASS="FILENAME"
>/dev</TT
> directory</TD
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|
