Chapter 3. After LFS
Configuration Issues
The intention of LFS is to provide a basic system which you can
build upon. There are several things about tidying up the system
which many people wonder about once they have done the base
install. We hope to cover these issues in this chapter.
Most people coming from non-Unix like backgrounds to Linux find
the concept of text-only configuration files slightly strange. In
Linux, just about all configuration is done via the manipulation
of text files. The majority of these files can be found in the
/etc hierarchy. There are often
graphical configuration programs available for different
subsystems but most are simply pretty front ends to the process
of editing a text file. The advantage of text-only configuration
is that you can edit parameters using your favorite text editor,
whether that be vim, emacs, or any other editor.
The first task is making a recovery boot device in Creating a Custom Boot Device
because it's the most critical need. Then the system is
configured to ease addition of new users, because this can affect
the choices you make in the two subsequent topics—The Bash Shell Startup Files
and The vimrc Files.
The remaining topics, Customizing your Logon
with /etc/issue, The
/etc/shells File, Random
number generation, Compressing man and info
pages, Autofs-5.0.3, and
Configuring for Network
Filesystems are then addressed, in that order. They don't
have much interaction with the other topics in this chapter.
Creating a Custom Boot
Device
Decent Rescue Boot Device Needs
This section is really about creating a rescue device. As the name
rescue implies, the
host system has a problem, often lost partition information
or corrupted file systems, that prevents it from booting
and/or operating normally. For this reason, you must not depend on resources from
the host being "rescued". To presume that any given partition
or hard drive will be
available is a risky presumption.
In a modern system, there are many devices that can be used
as a rescue device: floppy, cdrom, usb drive, or even a
network card. Which one you use depends on your hardware and
your BIOS. In the past, we usually thought of rescue device
as a floppy disk. Today, many systems do not even have a
floppy drive.
Building a complete rescue device is a challenging task. In
many ways, it is equivalent to building an entire LFS system.
In addition, it would be a repetition of information already
available. For these reasons, the procedures for a rescue
device image are not presented here.
Creating a Rescue Floppy
The software of today's systems has grown large. Linux 2.6 no
longer supports booting directly from a floppy. In spite of
this, there are solutions available using older versions of
Linux. One of the best is Tom's Root/Boot Disk available at
http://www.toms.net/rb/. This
will provide a minimal Linux system on a single floppy disk
and provides the ability to customize the contents of your
disk if necessary.
Creating a Bootable CD-ROM
There are several sources that can be used for a rescue
CD-ROM. Just about any commercial distribution's installation
CD-ROMs or DVDs will work. These include RedHat, Mandrake,
and SuSE. One very popular option is Knoppix.
Also, the LFS Community has developed its own LiveCD
available at http://www.linuxfromscratch.org/livecd/.
This LiveCD, in addition to having boot and rescue
capabilities, is capable of building an entire LFS/BLFS
system. A copy of this CD-ROM is available with the printed
version of the Linux From Scratch book. If you download the
ISO image, use cdrecord to copy the
image to a CD-ROM.
Creating a Bootable USB Drive
A USB Pen drive, sometimes called a Thumb drive, is
recognized by Linux as a SCSI device. Using one of these
devices as a rescue device has the advantage that it is
usually large enough to hold more than a minimal boot image.
You can save critical data to the drive as well as use it to
diagnose and recover a damaged system. Booting such a drive
requires BIOS support, but building the system consists of
formatting the drive, adding GRUB as well as the Linux kernel and
supporting files.
User Notes:
http://wiki.linuxfromscratch.org/blfs/wiki/CreatingaCustomBootDevice
Last updated on 2008-03-12 11:05:41 -0500
Configuring for Adding Users
Together, the /usr/sbin/useradd command and
/etc/skel directory (both are
easy to set up and use) provide a way to assure new users are
added to your LFS system with the same beginning settings for
things such as the PATH, keyboard
processing and other environmental variables. Using these two
facilities makes it easier to assure this initial state for
each new user added to the system.
The /etc/skel directory holds
copies of various initialization and other files that may be
copied to the new user's home directory when the /usr/sbin/useradd program
adds the new user.
Useradd
The useradd
program uses a collection of default values kept in
/etc/default/useradd. This file
is created in a base LFS installation by the Shadow package. If it has been removed or
renamed, the useradd program uses some
internal defaults. You can see the default values by running
/usr/sbin/useradd
-D.
To change these values, simply modify the /etc/default/useradd file as the root user. An alternative to directly
modifying the file is to run useradd as the root user while supplying the desired
modifications on the command line. Information on how to do
this can be found in the useradd man page.
/etc/skel
To get started, create an /etc/skel directory and make sure it is
writable only by the system administrator, usually root. Creating the directory as
root is the best way to go.
The mode of any files from this part of the book that you put
in /etc/skel should be writable
only by the owner. Also, since there is no telling what kind of
sensitive information a user may eventually place in their copy
of these files, you should make them unreadable by "group" and
"other".
You can also put other files in /etc/skel and different permissions may be
needed for them.
Decide which initialization files should be provided in every
(or most) new user's home directory. The decisions you make
will affect what you do in the next two sections, The Bash Shell Startup Files
and The vimrc Files. Some
or all of those files will be useful for root, any already-existing users, and new
users.
The files from those sections that you might want to place in
/etc/skel include .inputrc, .bash_profile, .bashrc, .bash_logout, .dircolors, and .vimrc. If you are unsure which of these
should be placed there, just continue to the following
sections, read each section and any references provided, and
then make your decision.
You will run a slightly modified set of commands for files
which are placed in /etc/skel.
Each section will remind you of this. In brief, the book's
commands have been written for files not added to /etc/skel and instead just sends the results
to the user's home directory. If the file is going to be in
/etc/skel, change the book's
command(s) to send output there instead and then just copy the
file from /etc/skel to the
appropriate directories, like /etc, ~ or the
home directory of any other user already in the system.
When Adding a User
When adding a new user with useradd, use the -m parameter, which tells useradd to create the user's
home directory and copy files from /etc/skel (can be overridden) to the new
user's home directory. For example (perform as the root user):
useradd -m <newuser>
Last updated on 2007-10-16 08:49:09 -0500
About System Users and Groups
Throughout BLFS, many packages install programs that run as
daemons or in some way should have a user or group name
assigned. Generally these names are used to map a user ID (uid)
or group ID (gid) for system use. Generally the specific uid or
gid numbers used by these applications are not significant. The
exception of course, is that root has a uid and gid of 0 (zero) that is
indeed special. The uid values are stored in /etc/passwd and the gid values are found in
/etc/group.
Customarily, Unix systems classify users and groups into two
categories: system users and regular users. The system users
and groups are given low numbers and regular users and groups
have numeric values greater than all the system values. The
cutoff for these numbers is found in two parameters in the
/etc/login.defs configuration
file. The default UID_MIN value is 1000 and the default GID_MIN
value is 100. If a specific uid or gid value is not specified
when creating a user with useradd or a group with
groupadd the
values assigned will always be above these cutoff values.
Additionally, the
Linux Standard Base recommends that system uid and gid
values should be below 100.
Below is a table of suggested uid/gid values used in BLFS
beyond those defined in a base LFS installation. These can be
changed as desired, but provide a suggested set of consistent
values.
Table 3.1. UID/GID Suggested Values
|
Name
|
uid
|
gid
|
|
bin
|
1
|
|
|
lp
|
9
|
|
|
messagebus
|
18
|
18
|
|
haldaemon
|
19
|
19
|
|
named
|
20
|
20
|
|
gdm
|
21
|
21
|
|
fcron
|
22
|
22
|
|
apache
|
25
|
25
|
|
smmsp
|
26
|
26
|
|
exim
|
31
|
31
|
|
postfix
|
32
|
32
|
|
postdrop
|
|
33
|
|
sendmail
|
34
|
|
|
mail
|
|
34
|
|
vmailman
|
35
|
35
|
|
news
|
36
|
36
|
|
mysql
|
40
|
40
|
|
postgres
|
41
|
41
|
|
ftp
|
45
|
45
|
|
proftpd
|
46
|
46
|
|
vsftpd
|
47
|
47
|
|
rsyncd
|
48
|
48
|
|
sshd
|
50
|
50
|
|
stunnel
|
51
|
51
|
|
svn
|
56
|
56
|
|
svntest
|
|
57
|
|
games
|
60
|
60
|
|
anonymous
|
98
|
|
|
nobody
|
99
|
|
|
nogroup
|
|
99
|
One value that is missing is 65534. This value is customarily
assigned to the user nobody and
group nogroup and is
unnecessary. The issue is explained in more detail in the first
note in the NFS Utilities Installation
section.
Last updated on 2008-03-12 11:05:41 -0500
Although most devices needed by packages in BLFS and beyond are
set up properly by udev using
the default rules installed by LFS in /etc/udev/rules.d, there are cases where the
rules must be modified or augmented.
User Notes: http://wiki.linuxfromscratch.org/blfs/wiki/aboutdevices
Multiple Sound Cards
If there are multiple sound cards in a system, the "default"
sound card becomes random. The method to establish sound card
order depends on whether the drivers are modules or not. If
the sound card drivers are compiled into the kernel, control
is via kernel command line parameters in /boot/grub/menu.lst. For example, if a
system has both an FM801 card and a SoundBlaster PCI card,
the following can be appended to the command line:
snd-fm801.index=0 snd-ens1371.index=1
If the sound card drivers are built as modules, the order can
be established in the /etc/modprobe.conf file with:
options snd-fm801 index=0
options snd-ens1371 index=1
Udev Device Attributes
Fine-tuning of device attributes such as group name and
permissions is possible by creating extra udev rules, matching on something like
this (on one line). The vendor and product can be found by
searching the /sys/devices directory entries or using
udevinfo after
the device has been attached. See the documentation in the
current udev directory of
/usr/share/doc for details.
SUBSYSTEM=="usb_device", SYSFS{idVendor}=="05d8",
SYSFS{idProduct}=="4002", GROUP:="scanner", MODE:="0640"
USB Device Issues
Some older applications, such as VMware, need the following deprecated
entry in the /etc/fstab file.
This is not normally needed.
usbfs /proc/bus/usb usbfs devgid=14,devmode=0660 0 0
Devices for Servers
In some cases, it makes sense to disable udev completely and create static
devices. Servers are one example of this situation. Does a
server need the capability of handling dynamic devices? Only
the system administrator can answer that question, but in
many cases the answer will be no.
If dynamic devices are not desired, then static devices must
be created on the system. In the default configuration, the
/etc/rc.d/rcsysinit.d/S10udev
boot script mounts a tmpfs
partition over the /dev
directory. This problem can be overcome by mounting the root
partition temporarily:
Warning
If the instructions below are not followed carefully, your
system could become unbootable.
mount --bind / /mnt
cp -a /dev/* /mnt/dev
rm /etc/rc.d/rcsysinit.d/{S10udev,S45udev_retry}
umount /mnt
At this point, the system will use static devices upon the
next reboot. Create any desired additional devices using
mknod.
If you want to restore the dynamic devices, recreate the
/etc/rc.d/rcsysinit.d/{S10udev,S45udev_retry}
symbolic links and reboot again. Static devices do not need
to be removed (console and null are always needed) because
they are covered by the tmpfs
partition. Disk usage for devices is negligible (about
20–30 bytes per entry.)
Last updated on 2007-04-14 05:46:41 -0500
The Bash Shell Startup Files
The shell program /bin/bash
(hereafter referred to as just "the shell") uses a collection
of startup files to help create an environment. Each file has a
specific use and may affect login and interactive environments
differently. The files in the /etc directory generally provide global
settings. If an equivalent file exists in your home directory
it may override the global settings.
An interactive login shell is started after a successful login,
using /bin/login, by reading the
/etc/passwd file. This shell
invocation normally reads /etc/profile and its private equivalent
~/.bash_profile upon startup.
An interactive non-login shell is normally started at the
command-line using a shell program (e.g., [prompt]$/bin/bash) or by the
/bin/su command.
An interactive non-login shell is also started with a terminal
program such as xterm or konsole from within a
graphical environment. This type of shell invocation normally
copies the parent environment and then reads the user's
~/.bashrc file for additional
startup configuration instructions.
A non-interactive shell is usually present when a shell script
is running. It is non-interactive because it is processing a
script and not waiting for user input between commands. For
these shell invocations, only the environment inherited from
the parent shell is used.
The file ~/.bash_logout is not
used for an invocation of the shell. It is read and executed
when a user exits from an interactive login shell.
Many distributions use /etc/bashrc for system wide initialization of
non-login shells. This file is usually called from the user's
~/.bashrc file and is not built
directly into bash itself. This convention
is followed in this section.
For more information see info
bash -- Nodes:
Bash Startup Files and Interactive Shells.
Note
Most of the instructions below are used to create files
located in the /etc directory
structure which requires you to execute the commands as the
root user. If you elect to
create the files in user's home directories instead, you
should run the commands as an unprivileged user.
/etc/profile
Here is a base /etc/profile.
This file starts by setting up some helper functions and some
basic parameters. It specifies some bash history parameters
and, for security purposes, disables keeping a permanent
history file for the root
user. It also sets a default user prompt. It then calls
small, single purpose scripts in the /etc/profile.d directory to provide most of
the initialization.
For more information on the escape sequences you can use for
your prompt (i.e., the PS1
environment variable) see info
bash -- Node:
Printing a Prompt.
cat > /etc/profile << "EOF"
# Begin /etc/profile
# Written for Beyond Linux From Scratch
# by James Robertson <jameswrobertson@earthlink.net>
# modifications by Dagmar d'Surreal <rivyqntzne@pbzpnfg.arg>
# System wide environment variables and startup programs.
# System wide aliases and functions should go in /etc/bashrc. Personal
# environment variables and startup programs should go into
# ~/.bash_profile. Personal aliases and functions should go into
# ~/.bashrc.
# Functions to help us manage paths. Second argument is the name of the
# path variable to be modified (default: PATH)
pathremove () {
local IFS=':'
local NEWPATH
local DIR
local PATHVARIABLE=${2:-PATH}
for DIR in ${!PATHVARIABLE} ; do
if [ "$DIR" != "$1" ] ; then
NEWPATH=${NEWPATH:+$NEWPATH:}$DIR
fi
done
export $PATHVARIABLE="$NEWPATH"
}
pathprepend () {
pathremove $1 $2
local PATHVARIABLE=${2:-PATH}
export $PATHVARIABLE="$1${!PATHVARIABLE:+:${!PATHVARIABLE}}"
}
pathappend () {
pathremove $1 $2
local PATHVARIABLE=${2:-PATH}
export $PATHVARIABLE="${!PATHVARIABLE:+${!PATHVARIABLE}:}$1"
}
# Set the initial path
export PATH=/bin:/usr/bin
if [ $EUID -eq 0 ] ; then
pathappend /sbin:/usr/sbin
unset HISTFILE
fi
# Setup some environment variables.
export HISTSIZE=1000
export HISTIGNORE="&:[bf]g:exit"
# Setup a red prompt for root and a green one for users.
NORMAL="\[\e[0m\]"
RED="\[\e[1;31m\]"
GREEN="\[\e[1;32m\]"
if [[ $EUID == 0 ]] ; then
PS1="$RED\u [ $NORMAL\w$RED ]# $NORMAL"
else
PS1="$GREEN\u [ $NORMAL\w$GREEN ]\$ $NORMAL"
fi
for script in /etc/profile.d/*.sh ; do
if [ -r $script ] ; then
. $script
fi
done
# Now to clean up
unset pathremove pathprepend pathappend
# End /etc/profile
EOF
The
/etc/profile.d Directory
Now create the /etc/profile.d
directory, where the individual initialization scripts are
placed:
install --directory --mode=0755 --owner=root --group=root /etc/profile.d
/etc/profile.d/dircolors.sh
This script uses the ~/.dircolors and /etc/dircolors files to control the
colors of file names in a directory listing. They control
colorized output of things like ls --color. The
explanation of how to initialize these files is at the end
of this section.
cat > /etc/profile.d/dircolors.sh << "EOF"
# Setup for /bin/ls to support color, the alias is in /etc/bashrc.
if [ -f "/etc/dircolors" ] ; then
eval $(dircolors -b /etc/dircolors)
if [ -f "$HOME/.dircolors" ] ; then
eval $(dircolors -b $HOME/.dircolors)
fi
fi
alias ls='ls --color=auto'
EOF
/etc/profile.d/extrapaths.sh
This script adds several useful paths to the PATH and PKG_CONFIG_PATH environment variables. If
you want, you can uncomment the last section to put a dot
at the end of your path. This will allow executables in the
current working directory to be executed without
specifiying a ./, however you are warned that this is
generally considered a security hazard.
cat > /etc/profile.d/extrapaths.sh << "EOF"
if [ -d /usr/local/lib/pkgconfig ] ; then
pathappend /usr/local/lib/pkgconfig PKG_CONFIG_PATH
fi
if [ -d /usr/local/bin ]; then
pathprepend /usr/local/bin
fi
if [ -d /usr/local/sbin -a $EUID -eq 0 ]; then
pathprepend /usr/local/sbin
fi
if [ -d ~/bin ]; then
pathprepend ~/bin
fi
#if [ $EUID -gt 99 ]; then
# pathappend .
#fi
EOF
/etc/profile.d/readline.sh
This script sets up the default inputrc configuration file. If the user
does not have individual settings, it uses the global file.
cat > /etc/profile.d/readline.sh << "EOF"
# Setup the INPUTRC environment variable.
if [ -z "$INPUTRC" -a ! -f "$HOME/.inputrc" ] ; then
INPUTRC=/etc/inputrc
fi
export INPUTRC
EOF
Setting the umask value is important
for security. Here the default group write permissions are
turned off for system users and when the user name and
group name are not the same.
cat > /etc/profile.d/umask.sh << "EOF"
# By default we want the umask to get set.
if [ "$(id -gn)" = "$(id -un)" -a $EUID -gt 99 ] ; then
umask 002
else
umask 022
fi
EOF
If X is installed, the
PATH and PKG_CONFIG_PATH variables are also updated.
cat > /etc/profile.d/X.sh << "EOF"
if [ -x /usr/X11R6/bin/X ]; then
pathappend /usr/X11R6/bin
fi
if [ -d /usr/X11R6/lib/pkgconfig ] ; then
pathappend /usr/X11R6/lib/pkgconfig PKG_CONFIG_PATH
fi
EOF
This script sets an environment variable necessary for
native language support. A full discussion on determining
this variable can be found on the LFS Bash
Shell Startup Files page.
cat > /etc/profile.d/i18n.sh << "EOF"
# Set up i18n variables
export LANG=<ll>_<CC>.<charmap><@modifiers>
EOF
Other
Initialization Values
Other initialization can easily be added to the
profile by adding additional
scripts to the /etc/profile.d
directory.
/etc/bashrc
Here is a base /etc/bashrc.
Comments in the file should explain everything you need.
cat > /etc/bashrc << "EOF"
# Begin /etc/bashrc
# Written for Beyond Linux From Scratch
# by James Robertson <jameswrobertson@earthlink.net>
# updated by Bruce Dubbs <bdubbs@linuxfromscratch.org>
# System wide aliases and functions.
# System wide environment variables and startup programs should go into
# /etc/profile. Personal environment variables and startup programs
# should go into ~/.bash_profile. Personal aliases and functions should
# go into ~/.bashrc
# Provides a colored /bin/ls command. Used in conjunction with code in
# /etc/profile.
alias ls='ls --color=auto'
# Provides prompt for non-login shells, specifically shells started
# in the X environment. [Review the LFS archive thread titled
# PS1 Environment Variable for a great case study behind this script
# addendum.]
NORMAL="\[\e[0m\]"
RED="\[\e[1;31m\]"
GREEN="\[\e[1;32m\]"
if [[ $EUID == 0 ]] ; then
PS1="$RED\u [ $NORMAL\w$RED ]# $NORMAL"
else
PS1="$GREEN\u [ $NORMAL\w$GREEN ]\$ $NORMAL"
fi
# End /etc/bashrc
EOF
~/.bash_profile
Here is a base ~/.bash_profile.
If you want each new user to have this file automatically,
just change the output of the command to /etc/skel/.bash_profile and check the
permissions after the command is run. You can then copy
/etc/skel/.bash_profile to the
home directories of already existing users, including
root, and set the owner and
group appropriately.
cat > ~/.bash_profile << "EOF"
# Begin ~/.bash_profile
# Written for Beyond Linux From Scratch
# by James Robertson <jameswrobertson@earthlink.net>
# updated by Bruce Dubbs <bdubbs@linuxfromscratch.org>
# Personal environment variables and startup programs.
# Personal aliases and functions should go in ~/.bashrc. System wide
# environment variables and startup programs are in /etc/profile.
# System wide aliases and functions are in /etc/bashrc.
append () {
# First remove the directory
local IFS=':'
local NEWPATH
for DIR in $PATH; do
if [ "$DIR" != "$1" ]; then
NEWPATH=${NEWPATH:+$NEWPATH:}$DIR
fi
done
# Then append the directory
export PATH=$NEWPATH:$1
}
if [ -f "$HOME/.bashrc" ] ; then
source $HOME/.bashrc
fi
if [ -d "$HOME/bin" ] ; then
append $HOME/bin
fi
unset append
# End ~/.bash_profile
EOF
~/.bashrc
Here is a base ~/.bashrc. The
comments and instructions for using /etc/skel for .bash_profile above also apply here. Only
the target file names are different.
cat > ~/.bashrc << "EOF"
# Begin ~/.bashrc
# Written for Beyond Linux From Scratch
# by James Robertson <jameswrobertson@earthlink.net>
# Personal aliases and functions.
# Personal environment variables and startup programs should go in
# ~/.bash_profile. System wide environment variables and startup
# programs are in /etc/profile. System wide aliases and functions are
# in /etc/bashrc.
if [ -f "/etc/bashrc" ] ; then
source /etc/bashrc
fi
# End ~/.bashrc
EOF
~/.bash_logout
This is an empty ~/.bash_logout
that can be used as a template. You will notice that the base
~/.bash_logout does not include
a clear
command. This is because the clear is handled in the
/etc/issue file.
cat > ~/.bash_logout << "EOF"
# Begin ~/.bash_logout
# Written for Beyond Linux From Scratch
# by James Robertson <jameswrobertson@earthlink.net>
# Personal items to perform on logout.
# End ~/.bash_logout
EOF
/etc/dircolors
If you want to use the dircolors capability, then run the
following command. The /etc/skel setup steps shown above also can
be used here to provide a ~/.dircolors file when a new user is set
up. As before, just change the output file name on the
following command and assure the permissions, owner, and
group are correct on the files created and/or copied.
dircolors -p > /etc/dircolors
If you wish to customize the colors used for different file
types, you can edit the /etc/dircolors file. The instructions for
setting the colors are embedded in the file.
Finally, Ian Macdonald has written an excellent collection of
tips and tricks to enhance your shell environment. You can
read it online at http://www.caliban.org/bash/index.shtml.
Last updated on 2008-05-09 08:00:42 -0500
The /etc/vimrc and ~/.vimrc
Files
The LFS book installs Vim as
its text editor. At this point it should be noted that there
are a lot of different
editing applications out there including Emacs, nano, Joe
and many more. Anyone who has been around the Internet
(especially usenet) for a short time will certainly have
observed at least one flame war, usually involving Vim and Emacs users!
The LFS book creates a basic vimrc file. In this section you'll find an
attempt to enhance this file. At startup, vim reads the global
configuration file (/etc/vimrc)
as well as a user-specific file (~/.vimrc). Either or both can be tailored to
suit the needs of your particular system.
Here is a slightly expanded .vimrc that you can put in ~/.vimrc to provide user specific effects. Of
course, if you put it into /etc/skel/.vimrc instead, it will be made
available to users you add to the system later. You can also
copy the file from /etc/skel/.vimrc to the home directory of
users already on the system, such as root. Be sure to set permissions, owner,
and group if you do copy anything directly from /etc/skel.
" Begin .vimrc
set columns=80
set wrapmargin=8
set ruler
" End .vimrc
Note that the comment tags are " instead of the more usual # or
//. This is correct, the syntax for vimrc is slightly unusual.
Below you'll find a quick explanation of what each of the
options in this example file means here:
-
set columns=80: This simply
sets the number of columns used on the screen.
-
set wrapmargin=8: This is the
number of characters from the right window border where
wrapping starts.
-
set ruler: This makes
vim show
the current row and column at the bottom right of the
screen.
More information on the many vim options can be found by
reading the help inside vim itself. Do this by typing
:help in vim to get the general help,
or by typing :help
usr_toc.txt to view the User Manual Table of Contents.
Last updated on 2007-10-16 08:02:24 -0500
Customizing your Logon with
/etc/issue
When you first boot up your new LFS system, the logon screen
will be nice and plain (as it should be in a bare-bones
system). Many people however, will want their system to display
some information in the logon message. This can be accomplished
using the file /etc/issue.
The /etc/issue file is a plain
text file which will also accept certain escape sequences (see
below) in order to insert information about the system. There
is also the file issue.net which
can be used when logging on remotely. ssh however, will only use it
if you set the option in the configuration file and will
not interpret the escape
sequences shown below.
One of the most common things which people want to do is clear
the screen at each logon. The easiest way of doing that is to
put a "clear" escape sequence into /etc/issue. A simple way of doing this is to
issue the command clear >
/etc/issue. This will insert the relevant
escape code into the start of the /etc/issue file. Note that if you do this,
when you edit the file, you should leave the characters
(normally '^[[H^[[2J') on the first line alone.
Note
Terminal escape sequences are special codes recognized by the
terminal. The ^[ represents an ASCII ESC character. The
sequence ESC [ H puts the cursor in the upper left hand
corner of the screen and ESC 2 J erases the screen. For more
information on terminal escape sequences see http://rtfm.etla.org/xterm/ctlseq.html
The following sequences are recognized by agetty (the program which
usually parses /etc/issue). This
information is from man
agetty where you can find extra information
about the logon process.
The issue file can contain
certain character sequences to display various information. All
issue sequences consist of a
backslash (\) immediately followed by one of the letters
explained below (so \d in
/etc/issue would insert the
current date).
b Insert the baudrate of the current line.
d Insert the current date.
s Insert the system name, the name of the operating system.
l Insert the name of the current tty line.
m Insert the architecture identifier of the machine, e.g., i686.
n Insert the nodename of the machine, also known as the hostname.
o Insert the domainname of the machine.
r Insert the release number of the kernel, e.g., 2.6.11.12.
t Insert the current time.
u Insert the number of current users logged in.
U Insert the string "1 user" or "<n> users" where <n> is the
number of current users logged in.
v Insert the version of the OS, e.g., the build-date etc.
Last updated on 2007-04-04 14:42:53 -0500
The shells file contains a list
of login shells on the system. Applications use this file to
determine whether a shell is valid. For each shell a single
line should be present, consisting of the shell's path,
relative to the root of the directory structure (/).
For example, this file is consulted by chsh to determine whether an
unprivileged user may change the login shell for her own
account. If the command name is not listed, the user will be
denied of change.
It is a requirement for applications such as GDM which does not populate the face
browser if it can't find /etc/shells, or FTP daemons which
traditionally disallow access to users with shells not included
in this file.
cat > /etc/shells << "EOF"
# Begin /etc/shells
/bin/sh
/bin/bash
# End /etc/shells
EOF
Last updated on 2007-04-04 14:42:53 -0500
The Linux kernel supplies a random number generator which is
accessed through /dev/random and
/dev/urandom. Programs that
utilize the random and urandom devices, such as OpenSSH, will benefit from these
instructions.
When a Linux system starts up without much operator
interaction, the entropy pool (data used to compute a random
number) may be in a fairly predictable state. This creates the
real possibility that the number generated at startup may
always be the same. In order to counteract this effect, you
should carry the entropy pool information across your
shut-downs and start-ups.
Install the /etc/rc.d/init.d/random init script included
with the blfs-bootscripts-20080816 package.
make install-random
Last updated on 2007-04-04 14:42:53 -0500
Compressing
Man and Info Pages
Man and info reader programs can transparently process files
compressed with gzip or bzip2, a feature you can use
to free some disk space while keeping your documentation
available. However, things are not that simple; man directories
tend to contain links—hard and symbolic—which
defeat simple ideas like recursively calling gzip on them. A better way to
go is to use the script below. If you would prefer to download
the file instead of creating it by typing or cut-and-pasting,
you can find it at
http://anduin.linuxfromscratch.org/files/BLFS/6.3/compressdoc
(the file should be installed in the /usr/sbin directory).
cat > /usr/sbin/compressdoc << "EOF"
#!/bin/bash
# VERSION: 20080421.1623
#
# Compress (with bzip2 or gzip) all man pages in a hierarchy and
# update symlinks - By Marc Heerdink <marc @ koelkast.net>
#
# Modified to be able to gzip or bzip2 files as an option and to deal
# with all symlinks properly by Mark Hymers <markh @ linuxfromscratch.org>
#
# Modified 20030930 by Yann E. Morin <yann.morin.1998 @ anciens.enib.fr>
# to accept compression/decompression, to correctly handle hard-links,
# to allow for changing hard-links into soft- ones, to specify the
# compression level, to parse the man.conf for all occurrences of MANPATH,
# to allow for a backup, to allow to keep the newest version of a page.
#
# Modified 20040330 by Tushar Teredesai to replace $0 by the name of the
# script.
# (Note: It is assumed that the script is in the user's PATH)
#
# Modified 20050112 by Randy McMurchy to shorten line lengths and
# correct grammar errors.
#
# Modified 20060128 by Alexander E. Patrakov for compatibility with Man-DB.
#
# Modified 20060311 by Archaic to use Man-DB manpath utility which is a
# replacement for man --path from Man.
#
# Modified 20080421 by Dan Nicholson to properly execute the correct
# compressdoc when working recursively. This means the same compressdoc
# will be used whether a full path was given or it was resolved from PATH.
#
# Modified 20080421 by Dan Nicholson to be more robust with directories
# that don't exist or don't have sufficient permissions.
#
# Modified 20080421 by Lars Bamberger to (sort of) automatically choose
# a compression method based on the size of the manpage. A couple bug
# fixes were added by Dan Nicholson.
#
# Modified 20080421 by Dan Nicholson to suppress warnings from manpath
# since these are emitted when $MANPATH is set. Removed the TODO for
# using the $MANPATH variable since manpath(1) handles this already.
#
# TODO:
# - choose a default compress method to be based on the available
# tool : gzip or bzip2;
# - offer an option to restore a previous backup;
# - add other compression engines (compress, zip, etc?). Needed?
# Funny enough, this function prints some help.
function help ()
{
if [ -n "$1" ]; then
echo "Unknown option : $1"
fi
( echo "Usage: $MY_NAME <comp_method> [options] [dirs]" && \
cat << EOT
Where comp_method is one of :
--gzip, --gz, -g
--bzip2, --bz2, -b
Compress using gzip or bzip2.
--automatic
Compress using either gzip or bzip2, depending on the
size of the file to be compressed. Files larger than 5
kB are bzipped, files larger than 1 kB are gzipped and
files smaller than 1 kB are not compressed.
--decompress, -d
Decompress the man pages.
--backup Specify a .tar backup shall be done for all directories.
In case a backup already exists, it is saved as .tar.old
prior to making the new backup. If a .tar.old backup
exists, it is removed prior to saving the backup.
In backup mode, no other action is performed.
And where options are :
-1 to -9, --fast, --best
The compression level, as accepted by gzip and bzip2.
When not specified, uses the default compression level
for the given method (-6 for gzip, and -9 for bzip2).
Not used when in backup or decompress modes.
--force, -F Force (re-)compression, even if the previous one was
the same method. Useful when changing the compression
ratio. By default, a page will not be re-compressed if
it ends with the same suffix as the method adds
(.bz2 for bzip2, .gz for gzip).
--soft, -S Change hard-links into soft-links. Use with _caution_
as the first encountered file will be used as a
reference. Not used when in backup mode.
--hard, -H Change soft-links into hard-links. Not used when in
backup mode.
--conf=dir, --conf dir
Specify the location of man_db.conf. Defaults to /etc.
--verbose, -v Verbose mode, print the name of the directory being
processed. Double the flag to turn it even more verbose,
and to print the name of the file being processed.
--fake, -f Fakes it. Print the actual parameters compressdoc will use.
dirs A list of space-separated _absolute_ pathnames to the
man directories. When empty, and only then, use manpath
to parse ${MAN_CONF}/man_db.conf for all valid occurrences
of MANDATORY_MANPATH.
Note about compression:
There has been a discussion on blfs-support about compression ratios of
both gzip and bzip2 on man pages, taking into account the hosting fs,
the architecture, etc... On the overall, the conclusion was that gzip
was much more efficient on 'small' files, and bzip2 on 'big' files,
small and big being very dependent on the content of the files.
See the original post from Mickael A. Peters, titled
"Bootable Utility CD", dated 20030409.1816(+0200), and subsequent posts:
http://linuxfromscratch.org/pipermail/blfs-support/2003-April/038817.html
On my system (x86, ext3), man pages were 35564KB before compression.
gzip -9 compressed them down to 20372KB (57.28%), bzip2 -9 got down to
19812KB (55.71%). That is a 1.57% gain in space. YMMV.
What was not taken into consideration was the decompression speed. But
does it make sense to? You gain fast access with uncompressed man
pages, or you gain space at the expense of a slight overhead in time.
Well, my P4-2.5GHz does not even let me notice this... :-)
EOT
) | less
}
# This function checks that the man page is unique amongst bzip2'd,
# gzip'd and uncompressed versions.
# $1 the directory in which the file resides
# $2 the file name for the man page
# Returns 0 (true) if the file is the latest and must be taken care of,
# and 1 (false) if the file is not the latest (and has therefore been
# deleted).
function check_unique ()
{
# NB. When there are hard-links to this file, these are
# _not_ deleted. In fact, if there are hard-links, they
# all have the same date/time, thus making them ready
# for deletion later on.
# Build the list of all man pages with the same name
DIR=$1
BASENAME=`basename "${2}" .bz2`
BASENAME=`basename "${BASENAME}" .gz`
GZ_FILE="$BASENAME".gz
BZ_FILE="$BASENAME".bz2
# Look for, and keep, the most recent one
LATEST=`(cd "$DIR"; ls -1rt "${BASENAME}" "${GZ_FILE}" "${BZ_FILE}" \
2>/dev/null | tail -n 1)`
for i in "${BASENAME}" "${GZ_FILE}" "${BZ_FILE}"; do
[ "$LATEST" != "$i" ] && rm -f "$DIR"/"$i"
done
# In case the specified file was the latest, return 0
[ "$LATEST" = "$2" ] && return 0
# If the file was not the latest, return 1
return 1
}
# Name of the script
MY_NAME=`basename $0`
# OK, parse the command-line for arguments, and initialize to some
# sensible state, that is: don't change links state, parse
# /etc/man_db.conf, be most silent, search man_db.conf in /etc, and don't
# force (re-)compression.
COMP_METHOD=
COMP_SUF=
COMP_LVL=
FORCE_OPT=
LN_OPT=
MAN_DIR=
VERBOSE_LVL=0
BACKUP=no
FAKE=no
MAN_CONF=/etc
while [ -n "$1" ]; do
case $1 in
--gzip|--gz|-g)
COMP_SUF=.gz
COMP_METHOD=$1
shift
;;
--bzip2|--bz2|-b)
COMP_SUF=.bz2
COMP_METHOD=$1
shift
;;
--automatic)
COMP_SUF=TBD
COMP_METHOD=$1
shift
;;
--decompress|-d)
COMP_SUF=
COMP_LVL=
COMP_METHOD=$1
shift
;;
-[1-9]|--fast|--best)
COMP_LVL=$1
shift
;;
--force|-F)
FORCE_OPT=-F
shift
;;
--soft|-S)
LN_OPT=-S
shift
;;
--hard|-H)
LN_OPT=-H
shift
;;
--conf=*)
MAN_CONF=`echo $1 | cut -d '=' -f2-`
shift
;;
--conf)
MAN_CONF="$2"
shift 2
;;
--verbose|-v)
let VERBOSE_LVL++
shift
;;
--backup)
BACKUP=yes
shift
;;
--fake|-f)
FAKE=yes
shift
;;
--help|-h)
help
exit 0
;;
/*)
MAN_DIR="${MAN_DIR} ${1}"
shift
;;
-*)
help $1
exit 1
;;
*)
echo "\"$1\" is not an absolute path name"
exit 1
;;
esac
done
# Redirections
case $VERBOSE_LVL in
0)
# O, be silent
DEST_FD0=/dev/null
DEST_FD1=/dev/null
VERBOSE_OPT=
;;
1)
# 1, be a bit verbose
DEST_FD0=/dev/stdout
DEST_FD1=/dev/null
VERBOSE_OPT=-v
;;
*)
# 2 and above, be most verbose
DEST_FD0=/dev/stdout
DEST_FD1=/dev/stdout
VERBOSE_OPT="-v -v"
;;
esac
# Note: on my machine, 'man --path' gives /usr/share/man twice, once
# with a trailing '/', once without.
if [ -z "$MAN_DIR" ]; then
MAN_DIR=`manpath -q -C "$MAN_CONF"/man_db.conf \
| sed 's/:/\\n/g' \
| while read foo; do dirname "$foo"/.; done \
| sort -u \
| while read bar; do echo -n "$bar "; done`
fi
# If no MANDATORY_MANPATH in ${MAN_CONF}/man_db.conf, abort as well
if [ -z "$MAN_DIR" ]; then
echo "No directory specified, and no directory found with \`manpath'"
exit 1
fi
# Check that the specified directories actually exist and are readable
for DIR in $MAN_DIR; do
if [ ! -d "$DIR" -o ! -r "$DIR" ]; then
echo "Directory '$DIR' does not exist or is not readable"
exit 1
fi
done
# Fake?
if [ "$FAKE" != "no" ]; then
echo "Actual parameters used:"
echo -n "Compression.......: "
case $COMP_METHOD in
--bzip2|--bz2|-b) echo -n "bzip2";;
--gzip|--gz|-g) echo -n "gzip";;
--automatic) echo -n "compressing";;
--decompress|-d) echo -n "decompressing";;
*) echo -n "unknown";;
esac
echo " ($COMP_METHOD)"
echo "Compression level.: $COMP_LVL"
echo "Compression suffix: $COMP_SUF"
echo -n "Force compression.: "
[ "foo$FORCE_OPT" = "foo-F" ] && echo "yes" || echo "no"
echo "man_db.conf is....: ${MAN_CONF}/man_db.conf"
echo -n "Hard-links........: "
[ "foo$LN_OPT" = "foo-S" ] &&
echo "convert to soft-links" || echo "leave as is"
echo -n "Soft-links........: "
[ "foo$LN_OPT" = "foo-H" ] &&
echo "convert to hard-links" || echo "leave as is"
echo "Backup............: $BACKUP"
echo "Faking (yes!).....: $FAKE"
echo "Directories.......: $MAN_DIR"
echo "Verbosity level...: $VERBOSE_LVL"
exit 0
fi
# If no method was specified, print help
if [ -z "${COMP_METHOD}" -a "${BACKUP}" = "no" ]; then
help
exit 1
fi
# In backup mode, do the backup solely
if [ "$BACKUP" = "yes" ]; then
for DIR in $MAN_DIR; do
cd "${DIR}/.."
if [ ! -w "`pwd`" ]; then
echo "Directory '`pwd`' is not writable"
exit 1
fi
DIR_NAME=`basename "${DIR}"`
echo "Backing up $DIR..." > $DEST_FD0
[ -f "${DIR_NAME}.tar.old" ] && rm -f "${DIR_NAME}.tar.old"
[ -f "${DIR_NAME}.tar" ] &&
mv "${DIR_NAME}.tar" "${DIR_NAME}.tar.old"
tar -cvf "${DIR_NAME}.tar" "${DIR_NAME}" > $DEST_FD1
done
exit 0
fi
# I know MAN_DIR has only absolute path names
# I need to take into account the localized man, so I'm going recursive
for DIR in $MAN_DIR; do
MEM_DIR=`pwd`
if [ ! -w "$DIR" ]; then
echo "Directory '$DIR' is not writable"
exit 1
fi
cd "$DIR"
for FILE in *; do
# Fixes the case were the directory is empty
if [ "foo$FILE" = "foo*" ]; then continue; fi
# Fixes the case when hard-links see their compression scheme change
# (from not compressed to compressed, or from bz2 to gz, or from gz
# to bz2)
# Also fixes the case when multiple version of the page are present,
# which are either compressed or not.
if [ ! -L "$FILE" -a ! -e "$FILE" ]; then continue; fi
# Do not compress whatis files
if [ "$FILE" = "whatis" ]; then continue; fi
if [ -d "$FILE" ]; then
# We are going recursive to that directory
echo "-> Entering ${DIR}/${FILE}..." > $DEST_FD0
# I need not pass --conf, as I specify the directory to work on
# But I need exit in case of error. We must change back to the
# original directory so $0 is resolved correctly.
(cd "$MEM_DIR" && eval "$0" ${COMP_METHOD} ${COMP_LVL} ${LN_OPT} \
${VERBOSE_OPT} ${FORCE_OPT} "${DIR}/${FILE}") || exit $?
echo "<- Leaving ${DIR}/${FILE}." > $DEST_FD1
else # !dir
if ! check_unique "$DIR" "$FILE"; then continue; fi
# With automatic compression, get the uncompressed file size of
# the file (dereferencing symlinks), and choose an appropriate
# compression method.
if [ "$COMP_METHOD" = "--automatic" ]; then
declare -i SIZE
case "$FILE" in
*.bz2)
SIZE=$(bzcat "$FILE" | wc -c) ;;
*.gz)
SIZE=$(zcat "$FILE" | wc -c) ;;
*)
SIZE=$(wc -c < "$FILE") ;;
esac
if (( $SIZE >= (5 * 2**10) )); then
COMP_SUF=.bz2
elif (( $SIZE >= (1 * 2**10) )); then
COMP_SUF=.gz
else
COMP_SUF=
fi
fi
# Check if the file is already compressed with the specified method
BASE_FILE=`basename "$FILE" .gz`
BASE_FILE=`basename "$BASE_FILE" .bz2`
if [ "${FILE}" = "${BASE_FILE}${COMP_SUF}" \
-a "foo${FORCE_OPT}" = "foo" ]; then continue; fi
# If we have a symlink
if [ -h "$FILE" ]; then
case "$FILE" in
*.bz2)
EXT=bz2 ;;
*.gz)
EXT=gz ;;
*)
EXT=none ;;
esac
if [ ! "$EXT" = "none" ]; then
LINK=`ls -l "$FILE" | cut -d ">" -f2 \
| tr -d " " | sed s/\.$EXT$//`
NEWNAME=`echo "$FILE" | sed s/\.$EXT$//`
mv "$FILE" "$NEWNAME"
FILE="$NEWNAME"
else
LINK=`ls -l "$FILE" | cut -d ">" -f2 | tr -d " "`
fi
if [ "$LN_OPT" = "-H" ]; then
# Change this soft-link into a hard- one
rm -f "$FILE" && ln "${LINK}$COMP_SUF" "${FILE}$COMP_SUF"
chmod --reference "${LINK}$COMP_SUF" "${FILE}$COMP_SUF"
else
# Keep this soft-link a soft- one.
rm -f "$FILE" && ln -s "${LINK}$COMP_SUF" "${FILE}$COMP_SUF"
fi
echo "Relinked $FILE" > $DEST_FD1
# else if we have a plain file
elif [ -f "$FILE" ]; then
# Take care of hard-links: build the list of files hard-linked
# to the one we are {de,}compressing.
# NB. This is not optimum has the file will eventually be
# compressed as many times it has hard-links. But for now,
# that's the safe way.
inode=`ls -li "$FILE" | awk '{print $1}'`
HLINKS=`find . \! -name "$FILE" -inum $inode`
if [ -n "$HLINKS" ]; then
# We have hard-links! Remove them now.
for i in $HLINKS; do rm -f "$i"; done
fi
# Now take care of the file that has no hard-link
# We do decompress first to re-compress with the selected
# compression ratio later on...
case "$FILE" in
*.bz2)
bunzip2 $FILE
FILE=`basename "$FILE" .bz2`
;;
*.gz)
gunzip $FILE
FILE=`basename "$FILE" .gz`
;;
esac
# Compress the file with the given compression ratio, if needed
case $COMP_SUF in
*bz2)
bzip2 ${COMP_LVL} "$FILE" && chmod 644 "${FILE}${COMP_SUF}"
echo "Compressed $FILE" > $DEST_FD1
;;
*gz)
gzip ${COMP_LVL} "$FILE" && chmod 644 "${FILE}${COMP_SUF}"
echo "Compressed $FILE" > $DEST_FD1
;;
*)
echo "Uncompressed $FILE" > $DEST_FD1
;;
esac
# If the file had hard-links, recreate those (either hard or soft)
if [ -n "$HLINKS" ]; then
for i in $HLINKS; do
NEWFILE=`echo "$i" | sed s/\.gz$// | sed s/\.bz2$//`
if [ "$LN_OPT" = "-S" ]; then
# Make this hard-link a soft- one
ln -s "${FILE}$COMP_SUF" "${NEWFILE}$COMP_SUF"
else
# Keep the hard-link a hard- one
ln "${FILE}$COMP_SUF" "${NEWFILE}$COMP_SUF"
fi
# Really work only for hard-links. Harmless for soft-links
chmod 644 "${NEWFILE}$COMP_SUF"
done
fi
else
# There is a problem when we get neither a symlink nor a plain
# file. Obviously, we shall never ever come here... :-(
echo -n "Whaooo... \"${DIR}/${FILE}\" is neither a symlink "
echo "nor a plain file. Please check:"
ls -l "${DIR}/${FILE}"
exit 1
fi
fi
done # for FILE
done # for DIR
EOF
As root, make compressdoc executable for
all users:
chmod -v 755 /usr/sbin/compressdoc
Now, as root, you can issue the
command compressdoc
--bz2 to compress all your system man pages.
You can also run compressdoc
--help to get comprehensive help about what the
script is able to do.
Don't forget that a few programs, like the X Window System and XEmacs also install their documentation in
non-standard places (such as /usr/X11R6/man, etc.). Be sure to add these
locations to the file /etc/man_db.conf, as MANDATORY_MANPATH </path> lines.
Example:
...
MANDATORY_MANPATH /usr/share/man
MANDATORY_MANPATH /usr/X11R6/man
MANDATORY_MANPATH /usr/local/man
MANDATORY_MANPATH /opt/qt/doc/man
...
Generally, package installation systems do not compress
man/info pages, which means you will need to run the script
again if you want to keep the size of your documentation as
small as possible. Also, note that running the script after
upgrading a package is safe; when you have several versions of
a page (for example, one compressed and one uncompressed), the
most recent one is kept and the others are deleted.
Last updated on 2008-04-21 18:27:43 -0500
Automate Mounting of
File Systems
Introduction to Autofs
The Autofs package contains
userspace tools that work with the kernel to mount and
un-mount removable file systems. The primary use is to mount
external network file systems like NFS (see NFS
Utilities-1.1.2) or Samba (see Samba-3.0.30) on demand.
It may also be useful for allowing users to mount floppies,
cdroms and other removable storage devices without requiring
the system administrator to mount the devices although this
capability is now generally provided by HAL (see HAL-0.5.9.1). This
may not be ideal for all installations, so be aware of the
risks before implementing this feature.
Package Information
Additional Downloads
Recommended Patches: There are frequent patches issued for
Autofs. One method you can
use to get the current patches requires first installing the
Wget-1.10.2 package. After ensuring the
wget command is
installed in a directory identified in the PATH variable, start in the same directory as
the main tar file and issue the following commands:
wget http://ftp.kernel.org/pub/linux/daemons/autofs/v5/patch_order-5.0.3 &&
sed 's;autofs;http://ftp.kernel.org/pub/linux/daemons/autofs/v5/autofs;' \
patch_order-5.0.3 > wget-list &&
wget -i wget-list
Autofs Dependencies
Optional
OpenLDAP-2.3.39 and Cyrus
SASL-2.1.22
User Notes: http://wiki.linuxfromscratch.org/blfs/wiki/autofs
Kernel
Configuration
Verify that kernel support has been compiled in or built as
modules in the following areas:
File systems ⇒
Kernel automounter version 4 support Y or M
Network File Systems ⇒
NFS file system support Y or M (optional)
SMB file system support Y or M (optional)
Recompile and install the new kernel, if necessary.
Installation of Autofs
Install Autofs by running
the following commands:
for f in `cat ../patch_order-5.0.3`; do
patch -Np1 -i ../$f
done &&
./configure --prefix=/ --mandir=/usr/share/man &&
make
This package does not come with a test suite.
Now, as the root user:
make install &&
ln -sf ../init.d/autofs /etc/rc.d/rcsysinit.d/S52autofs
Command Explanations
for f in `cat
../patch_order-5.0.3`; do patch -Np1 -i ../$f;
done: This command applies all the patches
downloaded earlier in the correct order.
ln -sf ../init.d/autofs
/etc/rc.d/rcsysinit.d/S52autofs: This command
sets the link to properly start autofs upon boot.
Configuring Autofs
/etc/sysconfig/autofs.conf,
/etc/auto.master,
/etc/auto.misc, and
/etc/auto.net
Configuration
Information
The installation process creates auto.master, auto.misc, auto.smb, and auto.net. Replace the auto.master file with the following
commands:
mv /etc/auto.master /etc/auto.master.bak &&
cat > /etc/auto.master << "EOF"
# Begin /etc/auto.master
/media/auto /etc/auto.misc --ghost
#/home /etc/auto.home
# End /etc/auto.master
EOF
This file creates a new media directory, /media/auto that will overlay any
existing directory of the same name. In this example, the
file, /etc/auto.misc, has a
line:
cd -fstype=iso9660,ro,nosuid,nodev :/dev/cdrom
that will mount a cdrom as /media/auto/cd if that directory is
accessed. The --ghost option
tells the automounter to create “ghost” versions (i.e. empty
directories) of all the mount points listed in the
configuration file regardless whether any of the file
systems are actually mounted or not. This is very
convenient and highly recommended, because it will show you
the available auto-mountable file systems as existing
directories, even when their file systems aren't currently
mounted. Without the --ghost
option, you'll have to remember the names of the
directories. As soon as you try to access one of them, the
directory will be created and the file system will be
mounted. When the file system gets unmounted again, the
directory is destroyed too, unless the --ghost option was given.
Note
An alternative method would be to specify another
automount location such as /var/lib/auto/cdrom and create a
symbolic link from /media/cdrom to the automount location.
The auto.misc file must be
configured to your working hardware. The loaded
configuration file should load your cdrom if /dev/cdrom is active or it can be edited
to match your device setup. Examples for floppies are
available in the file and easily activated. Documentation
for this file is available using the man 5 autofs command.
In the second line, if enabled, a user's home directory
would be mounted via NFS upon login. The /etc/home.auto would need to exist and
have an entry similar to:
joe example.org:/export/home/joe
where the directory /export/home/joe is exported via NFS from
the system example.org. NFS shares are covered on the next
page.
This package could also be used to mount SMB shares,
however that feature is not configured in these
instructions. For additional configuration information, see
the man pages for auto.master(5). There are also web
resources such as this
AUTOFS HOWTO available.
Contents
Installed Program:
automount
Installed Libraries:
lookup_file.so, lookup_hosts.so,
lookup_multi.so, lookup_nisplus.so, lookup_program.so,
lookup_userhome.so, lookup_yp.so, mount_afs.so,
mount_autofs.so, mount_bind.so, mount_changer.so,
mount_ext2.so, mount_generic.so, mount_nfs.so,
parse_sun.so
Installed Directories:
/lib/autofs and
/var/run/autofs
Short Descriptions
|
automount
|
is the daemon that performs the mounting when a
request is made for the device.
|
Last updated on 2008-08-11 15:01:37 -0500
Configuring for Network
Filesystems
While LFS is capable of mounting network file systems such as
NFS, these are not mounted by the mountfs init script. Network file systems
must be mounted after the networking is activated and unmounted
before the network goes down. The netfs bootscript was written to handle both
boot-time mounting of network filesystems, if the entry in
/etc/fstab contains the
_netdev option, and unmounting of
all network filesystems before the network is brought down.
As the root user, install the
/etc/rc.d/init.d/netfs bootscript
included with the blfs-bootscripts-20080816 package.
make install-netfs
Last updated on 2007-04-04 14:42:53 -0500