572 lines
8.5 KiB
HTML
572 lines
8.5 KiB
HTML
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
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<HTML
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><HEAD
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><TITLE
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>The /etc directory</TITLE
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><META
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NAME="GENERATOR"
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CONTENT="Modular DocBook HTML Stylesheet Version 1.7"><LINK
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REL="HOME"
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TITLE="Linux System Administrators Guide"
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HREF="index.html"><LINK
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TITLE="Overview of the Directory Tree"
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HREF="dir-tree-overview.html"><LINK
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REL="PREVIOUS"
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TITLE="The root filesystem"
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HREF="root-fs.html"><LINK
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TITLE="The /dev directory"
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HREF="dev-fs.html"></HEAD
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CLASS="SECT1"
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BGCOLOR="#FFFFFF"
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TEXT="#000000"
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LINK="#0000FF"
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VLINK="#840084"
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ALINK="#0000FF"
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><DIV
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CLASS="NAVHEADER"
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><TABLE
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SUMMARY="Header navigation table"
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WIDTH="100%"
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><TR
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><TH
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COLSPAN="3"
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ALIGN="center"
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>Linux System Administrators Guide: </TH
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></TR
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><TR
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><TD
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WIDTH="10%"
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ALIGN="left"
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VALIGN="bottom"
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><A
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HREF="root-fs.html"
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ACCESSKEY="P"
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>Prev</A
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></TD
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><TD
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WIDTH="80%"
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ALIGN="center"
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VALIGN="bottom"
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>Chapter 3. Overview of the Directory Tree</TD
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><TD
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WIDTH="10%"
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ALIGN="right"
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VALIGN="bottom"
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><A
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HREF="dev-fs.html"
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ACCESSKEY="N"
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>Next</A
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></TD
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></TR
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></TABLE
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><HR
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ALIGN="LEFT"
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WIDTH="100%"></DIV
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><DIV
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CLASS="SECT1"
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><H1
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CLASS="SECT1"
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><A
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NAME="ETC-FS"
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></A
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>3.3. The <TT
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CLASS="FILENAME"
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>/etc</TT
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> directory</H1
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><P
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>The <TT
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CLASS="FILENAME"
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>/etc</TT
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> maintains a lot
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of files. Some of them are described below. For others, you
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should determine which program they belong to and read the manual
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page for that program. Many networking configuration files are
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in <TT
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CLASS="FILENAME"
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>/etc</TT
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> as well, and are described in the
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<I
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CLASS="CITETITLE"
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>Networking Administrators' Guide</I
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>.
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<DIV
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CLASS="GLOSSLIST"
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><DL
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><DT
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><B
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><TT
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CLASS="FILENAME"
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>/etc/rc</TT
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> or
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<TT
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CLASS="FILENAME"
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>/etc/rc.d</TT
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> or
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<TT
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CLASS="FILENAME"
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>/etc/rc?.d</TT
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></B
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></DT
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><DD
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><P
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>Scripts or directories of scripts
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to run at startup or when changing the run level.
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See <A
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HREF="major-services.html#INIT"
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>Section 2.3.1</A
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> for further
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information. </P
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></DD
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><DT
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><B
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><TT
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CLASS="FILENAME"
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>/etc/passwd</TT
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></B
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></DT
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><DD
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><P
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>The user database, with fields giving the
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username, real name, home directory, and other information
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about each user. The format is documented in the
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<B
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CLASS="COMMAND"
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>passwd</B
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> manual page.
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</P
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></DD
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><DT
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><B
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><TT
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CLASS="FILENAME"
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>/etc/shadow</TT
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></B
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></DT
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><DD
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><P
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><TT
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CLASS="FILENAME"
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>/etc/shadow</TT
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> is an
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encrypted file the holds user passwords.</P
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></DD
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><DT
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><B
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><TT
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CLASS="FILENAME"
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>/etc/fdprm</TT
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></B
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></DT
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><DD
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><P
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>Floppy disk parameter table.
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Describes what different floppy disk formats look
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like. Used by <B
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CLASS="COMMAND"
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>setfdprm</B
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>
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. See the
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<B
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CLASS="COMMAND"
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>setfdprm</B
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> manual page for more
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information. </P
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></DD
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><DT
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><B
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><TT
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CLASS="FILENAME"
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>/etc/fstab</TT
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></B
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></DT
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><DD
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><P
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>Lists the filesystems mounted automatically
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at startup by the <B
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CLASS="COMMAND"
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>mount -a</B
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> command (in
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<TT
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CLASS="FILENAME"
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>/etc/rc</TT
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> or equivalent startup file).
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Under Linux, also contains information about swap areas used
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automatically by <B
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CLASS="COMMAND"
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>swapon -a</B
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>
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. See <A
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HREF="filesystems.html#MOUNT-AND-UMOUNT"
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>Section 5.10.7</A
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> and the <B
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CLASS="COMMAND"
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>mount</B
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>
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manual page for more information. Also
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<TT
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CLASS="FILENAME"
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>fstab</TT
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> usually has its own manual page in
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section 5. </P
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></DD
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><DT
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><B
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><TT
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CLASS="FILENAME"
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>/etc/group</TT
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></B
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></DT
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><DD
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><P
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>Similar to <TT
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CLASS="FILENAME"
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>/etc/passwd</TT
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>,
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but describes groups instead of users. See the
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<TT
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CLASS="FILENAME"
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>group</TT
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> manual page in section 5 for more
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information. </P
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></DD
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><DT
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><B
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><TT
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CLASS="FILENAME"
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>/etc/inittab</TT
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></B
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></DT
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><DD
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><P
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>Configuration file for
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<B
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CLASS="COMMAND"
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>init</B
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>. </P
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></DD
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><DT
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><B
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><TT
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CLASS="FILENAME"
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>/etc/issue</TT
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></B
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></DT
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><DD
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><P
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>Output by <B
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CLASS="COMMAND"
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>getty</B
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>
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before
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the login prompt. Usually contains a short description or
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welcoming message to the system. The contents are up to
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the system administrator. </P
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></DD
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><DT
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><B
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><TT
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CLASS="FILENAME"
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>/etc/magic</TT
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></B
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></DT
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><DD
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><P
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>The configuration file
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for <B
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CLASS="COMMAND"
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>file</B
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>. Contains the
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descriptions of various file formats based on
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which <B
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CLASS="COMMAND"
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>file</B
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> guesses the type of
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the file. See the <TT
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CLASS="FILENAME"
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>magic</TT
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> and
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<B
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CLASS="COMMAND"
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>file</B
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> manual pages for more information.
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</P
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></DD
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><DT
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><B
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><TT
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CLASS="FILENAME"
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>/etc/motd</TT
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></B
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></DT
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><DD
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><P
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>The message of the day, automatically
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output after a successful login. Contents are up to the
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system administrator. Often used for getting information
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to every user, such as warnings about planned downtimes.
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</P
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></DD
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><DT
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><B
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><TT
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CLASS="FILENAME"
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>/etc/mtab</TT
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></B
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></DT
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><DD
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><P
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>List of currently mounted filesystems.
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Initially set up by the bootup scripts, and updated
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automatically by the <B
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CLASS="COMMAND"
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>mount</B
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>
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command. Used when a list of mounted filesystems is
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needed, e.g., by the <B
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CLASS="COMMAND"
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>df</B
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>
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command.
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</P
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></DD
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><DT
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><B
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><TT
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CLASS="FILENAME"
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>/etc/login.defs</TT
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></B
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></DT
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><DD
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><P
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>Configuration file for the
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<B
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CLASS="COMMAND"
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>login</B
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> command. The
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<TT
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CLASS="FILENAME"
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>login.defs</TT
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> file usually has a manual
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page in section 5. </P
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></DD
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><DT
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><B
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><TT
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CLASS="FILENAME"
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>/etc/printcap</TT
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></B
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></DT
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><DD
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><P
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>Like <TT
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CLASS="FILENAME"
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>/etc/termcap</TT
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>
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<I
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CLASS="GLOSSTERM"
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><TT
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CLASS="FILENAME"
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>/etc/printcap</TT
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>
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, but
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intended for printers. However it uses different syntax.
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The <TT
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CLASS="FILENAME"
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>printcap</TT
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> has a manual page in
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section 5. </I
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></P
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></DD
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><DT
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><B
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><TT
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CLASS="FILENAME"
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>/etc/profile</TT
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>,
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<TT
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CLASS="FILENAME"
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>/etc/bash.rc</TT
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>,
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<TT
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CLASS="FILENAME"
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>/etc/csh.cshrc</TT
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></B
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></DT
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><DD
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><P
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>Files executed at login or startup time
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by the Bourne, BASH
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,
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or C
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shells. These allow the system
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administrator to set global defaults for all users. Users
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can also create individual copies of these in their home
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directory to personalize their environment.
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See the manual pages for the respective shells.
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</P
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></DD
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><DT
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><B
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><TT
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CLASS="FILENAME"
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>/etc/securetty</TT
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></B
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></DT
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><DD
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><P
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>Identifies secure terminals, i.e., the
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terminals from which root is allowed to log in. Typically
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only the virtual consoles are listed, so that it becomes
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impossible (or at least harder) to gain superuser privileges
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by breaking into a system over a modem or a network. Do not
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allow root logins over a network. Prefer to log in as an
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unprivileged user and use <B
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CLASS="COMMAND"
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>su</B
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>
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or
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<B
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CLASS="COMMAND"
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>sudo</B
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> to gain root
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privileges.</P
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></DD
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><DT
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><B
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><TT
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CLASS="FILENAME"
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>/etc/shells</TT
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></B
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></DT
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><DD
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><P
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>Lists trusted shells. The
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<B
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CLASS="COMMAND"
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>chsh</B
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> command allows users to change
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their login shell only to shells listed in this file.
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<B
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CLASS="COMMAND"
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>ftpd</B
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>, is the server process that provides
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FTP services for a machine, will check that the user's
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shell is listed in <TT
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CLASS="FILENAME"
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>/etc/shells</TT
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>
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and will not let people log in unless the shell is
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listed there. </P
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></DD
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><DT
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><B
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><TT
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CLASS="FILENAME"
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>/etc/termcap</TT
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></B
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></DT
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><DD
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><P
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>The terminal capability database.
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Describes by what ``escape sequences'' various terminals
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can be controlled. Programs are written so that instead
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of directly outputting an escape sequence that only
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works on a particular brand of terminal, they look up
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the correct sequence to do whatever it is they want to
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do in <TT
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CLASS="FILENAME"
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>/etc/termcap</TT
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>. As a result
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most programs work with most kinds of terminals.
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See the <TT
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CLASS="FILENAME"
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>termcap</TT
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>, curs_termcap,
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and <TT
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CLASS="FILENAME"
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>terminfo</TT
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> manual pages for
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more information. </P
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></DD
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></DL
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></DIV
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>
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</P
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></DIV
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><DIV
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CLASS="NAVFOOTER"
|
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><HR
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ALIGN="LEFT"
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WIDTH="100%"><TABLE
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SUMMARY="Footer navigation table"
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WIDTH="100%"
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BORDER="0"
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CELLPADDING="0"
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CELLSPACING="0"
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><TR
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><TD
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WIDTH="33%"
|
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ALIGN="left"
|
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VALIGN="top"
|
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><A
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HREF="root-fs.html"
|
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ACCESSKEY="P"
|
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>Prev</A
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></TD
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><TD
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WIDTH="34%"
|
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ALIGN="center"
|
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VALIGN="top"
|
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><A
|
|
HREF="index.html"
|
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ACCESSKEY="H"
|
|
>Home</A
|
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></TD
|
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><TD
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WIDTH="33%"
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ALIGN="right"
|
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VALIGN="top"
|
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><A
|
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HREF="dev-fs.html"
|
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ACCESSKEY="N"
|
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>Next</A
|
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></TD
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></TR
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><TR
|
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><TD
|
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WIDTH="33%"
|
|
ALIGN="left"
|
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VALIGN="top"
|
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>The root filesystem</TD
|
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><TD
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WIDTH="34%"
|
|
ALIGN="center"
|
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VALIGN="top"
|
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><A
|
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HREF="dir-tree-overview.html"
|
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ACCESSKEY="U"
|
|
>Up</A
|
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></TD
|
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><TD
|
|
WIDTH="33%"
|
|
ALIGN="right"
|
|
VALIGN="top"
|
|
>The <TT
|
|
CLASS="FILENAME"
|
|
>/dev</TT
|
|
> directory</TD
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></TR
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></TABLE
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></DIV
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></BODY
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></HTML
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> |