TITLE: Setting up Automount LFS VERSION: Any AUTHOR: R. Cort Tompkins SPECIAL THANKS TO: Tan Siong Hua SYNOPSIS: The mounting and unmounting of removable media is a tedious task, especially when it needs to be done by unprivileged users. Automount is a utility that will automatically unmount specified devices after a given interval, and then remount them automatically upon subsequent access. This makes the mount/unmount process relatively transparent to the end user. HINT: To get started you'll need a few things: 1) Automount support in the kernel. This is compiled into the kernel by default unless you explicitly removed it during kernel configuration. If this is the case, reconfigure your kernel (i.e. "make menuconfig" in your kernel source directory) and enable Automount v4 as a built-in feature under the "File Systems" heading. 2) The automount user utilities. Download the latest version 3 utilities from ftp://ftp.kernel.org/pub/linux/daemons/autofs (autofs-3.1.7.tar.bz2 at the time of this writing). Extract this archive and cd into it. Before compilation and installation, we'll take preemptive action to stop a compile-time error: $ cp modules/lookup_program.c modules/lookup_program.c.old $ sed "s/OPEN_MAX/FOPEN_MAX/" modules/lookup_program.c.old > \ modules/lookup_program.c $ ./configure --prefix=/usr --sbindir=/sbin $ make $ make install If you look in the sample subdirectory, you'll find rc.autofs, a startup script designed to help automate the automounting process. Use this if you wish, but I will give instructions for creating a slightly simpler script which should help you better understand the workings of automount. First we'll create the script itself, as root: $ cat > /etc/rc.d/init.d/auto_mount << "EOF" #!/bin/bash # Begin /etc/rc.d/init.d/auto_mount # # Automount script by Cort Tompkins - rtompkin@cs.odu.edu, derived # from ethnet script by Gerard Beekmans - gerard@linuxfromscratch.org source /etc/rc.d/init.d/functions case "$1" in start) for mountspec in $(/bin/ls /etc/sysconfig/automount-config/*.auto) do source $mountspec MOUNT_BASE=${mountspec%.auto} echo "Starting automount for group ${MOUNT_BASE##*/} ..." /sbin/automount --timeout=${TIMEOUT} $MOUNTPOINT file \ $MOUNT_BASE.map evaluate_retval done ;; # assume all instances of automount were started by this script stop) echo -n "Stopping automount ..." # Unmount everything mounted by automount /bin/killall -USR1 automount /bin/killall automount evaluate_retval ;; restart) $0 stop sleep 1 $0 start ;; *) echo "Usage: $0 {start|stop|restart}" exit 1 ;; esac # End /etc/rc.d/init.d/auto_mount EOF Please resist the temptation to name the startup script "automount." This means that the script will get the same kill signals we send to automount proper. Give the script proper permissions: $ chmod 754 /etc/rc.d/init.d/auto_mount Since I use automount for network shares, I only want it to be running when in a networkable state. On the very rare occasion that you find yourself in an unnetworked runlevel, you can always mount your removable devices manually. $ cd /etc/rc.d $ for rl in $(seq 0 2; echo 6); do > cd rc${rl}.d > ln -s ../init.d/auto_mount K45auto_mount > cd .. > done $ for rl in $(seq 3 5); do > cd rc${rl}.d > ln -s ../init.d/auto_mount S25auto_mount > cd .. > done Create the sysconfig directory that the script will use: $ mkdir /etc/sysconfig/automount-config Inside /etc/sysconfig/automount-config/, you'll create pairs of files for each group of devices you wish to automount. The format of the files is as follows: xxxx.auto: MOUNTPOINT=/path/to/mountdir TIMEOUT=999 xxxx.map: MOUNTNAME -fstype=FSTYPE[,OPTIONS] :/path/to/device MOUNTNAME -fstype=FSTYPE[,OPTIONS] :/path/to/device DO NOT create the "MOUNTNAME" directory under the "MOUNTPOINT" yourself. Automount will create and remove this directory as needed. The format of the .auto files is arbitrarily determined by the workings of the auto_mount script; more information on the format of the .map files can be found using "man 5 autofs". The OPTIONS used in the .map file are the same options you would pass to mount with the -o flag. Note that you can have multiple entries in a .map file, but they will all assume the same mountpoint and timeout specified in the corresponding .auto file of the same prefix. The auto_mount script can handle any number of .map/.auto pairs (so long as the pairs both have the same prefix). Here are some examples: -- cdrom.auto: MOUNTPOINT=/mnt TIMEOUT=5 cdrom.map: cd -fstype=iso9660,ro :/dev/cdrom -- The above pair will automount /dev/cdrom at /mnt/cd with a timeout of 5 seconds. This means that after five seconds of inactivity the cdrom device will be automatically unmounted, allowing you to put in a new CD to be automatically remounted upon subsequent access. You can verify this after initializing automount: $ ls /mnt/cd; mount You will see that the cdrom is mounted. Wait five seconds. $ mount If everything is working properly, automount will have unmounted the cdrom. Subsequent access to /mnt/cd will cause it to be remounted. Most CD drives lock their CD trays while mounted, preventing you from removing the media while the drive is mounted. Floppy drives, on the other hand, have no such protection; it is best to keep their timeout value as small as possible: -- floppy.auto: MOUNTPOINT=/mnt TIMEOUT=1 floppy.map: flop -fstype=auto :/dev/fd0 -- This mounts the floppy drive at /mnt/flop. Note that a timeout of 0 will disable the automatic unmounting altogether. Automount can also be used to mount network shares: -- samba.auto: MOUNTPOINT=/smb/win2kbox TIMEOUT=300 samba.map: c -fstype=smbfs,username=samba,password=xxxx ://win2kbox/c d -fstype=smbfs,username=samba,password=xxxx ://win2kbox/d -- The two samba shares specified will be automounted at /smb/win2kbox/c and /smb/win2kbox/d One final note of caution (from the autofs man page): UNSUPPORTED: The automounter does not support direct maps or mount trees (more than one file system to be mounted under a spe- cific automount point)... This (unfortunately) means that you can't have separate .auto/.map pairs with the same MOUNTPOINT. Thus, the individual floppy and cdrom examples used above cannot be used together! The best alternative in this case is to combine them into one file pair: -- removables.auto: MOUNTPOINT=/mnt TIMEOUT=1 removable.map: cd -fstype=iso9660,ro :/dev/cdrom flop -fstype=auto :/dev/fd0 -- The more adventurous among you may also consider compiling and installing automount v4 (beta). Its compilation and installation is virtually identical to that outlined above, with the exception of the patching of lookup_module.c (the first block of commands). Upgrading is as simple as: $ tar xvfj autofs-4.0.0pre10.tar.bz2 $ cd autofs-4.0.0pre10 $ ./configure --prefix=/usr --sbindir=/sbin && make && make install $ /etc/rc.d/init.d/auto_mount restart Feel free to e-mail me with questions or suggestions.