Quick autofs Tutorial

By Mark Nielsen

What is autofs? Autofs uses automount to mount cdrom and floppy drives (and other things) to your computer as you need them and umount as they are not being used. What is mount and unmount? Mount and umount are programs to mount a device ontop of a directory. For example, this command would mount the first floppy drive (drive a: in DOS terms) to the directory "/mnt/floppy" so that everytime you access "/mnt/floppy" to access your floppy drive.

mount /dev/fd0 /mnt/floppy

And this command unmounts or frees up the floppy drive from being used.

    

umount /dev/fd0 

Now, in DOS terms, your floppy disk is accessed as you need it. For normal users, that is what they would expect. They wouldn't want to use mount and umount because it is time consuming and because they might not get it right.

I assume "/dev/cdrom" is your cdrom drive and "dev/fd0" is your floppy drive. I am also assuming you will backup your "/etc/auto.master" file. Use this script to create the following threes files and restart autofs. Login as "root", goto your home directory, copy whatever between the next two lines to a file called "CreateAutofs.script" and execute the script with the command

 

source CreateAutofs.script

cd

echo "Please ignore any errors when making directories"

     ### Let us make sure the two directories exist, ignore errors

mkdir /mnt/floppy

mkdir /mnt/cdrom

     ### Let us backup the auto files in case they haven't

mv /etc/auto.master /etc/auto.master_old

mv /etc/auto.floppy /etc/auto.floppy_old

mv /etc/auto.cdrom /etc/auto.cdrom_old

     ### Create the files for autofs

echo "/mnt/cdrom /etc/auto.cdrom --timeout 10" > /etc/auto.master

echo "/mnt/floppy /etc/auto.floppy --timeout 1" >> /etc/auto.master

echo "floppy   -user,suid,fstype=msdos :/dev/fd0" > /etc/auto.floppy

echo "cdrom    -fstype=iso9660,ro   :/dev/cdrom" > /etc/auto.cdrom

     ### Create the links to the floppy drive and cdrom drive

ln -s /mnt/floppy/floppy a:

ln -s /mnt/cdrom/cdrom d:

ln -s /mnt/floppy/floppy floppy

ln -s /mnt/cdrom/cdrom cdrom 

     ### Lets retstart autofs, you might have to reboot

cd /etc/rc.d/init.d

./autofs restart

     ### If it didn't work, you might have to reboot 

     ### Try "./autofs start" if the restart claims autofs has not been

     #### started

cd

The end of your results should look something like the following if it was sucessfull

Start /usr/sbin/automount --timeout 10 /mnt/cdrom file /etc/auto.cdrom

Start /usr/sbin/automount --timeout 1 /mnt/floppy file /etc/auto.floppy

ls a:

ls d:

Personally, my /etc/auto.floppy file looks like

floppy          -fstype=auto,defaults,user,suid :/dev/fd0

cdrom           -fstype=iso9660,user,suid       :/dev/cdrom

If you noticed the timeout value for the floppy drive is 1 second. This makes it so that by the time the floppy drive light has gone out, your floppy disk is unmounted and a normal user can take the floppy disk out and "nothing bad happens". I made the timeout value for the cdrom 10 seconds because it wasn't working really well at 1 second, and I figured it was because the drive didn't have enough time to "warm up" before it was being shut down. You might want to test what the timeout value for your cdrom drive should be.

To get more information about autofs, do the commands

man 5 autofs

man autofs

Now to explain it

Your "/etc/rc.d/init.d/autofs" script first looks at "/etc/auto.master". That file usually has three things on each line. It has the directory which all mounts will be located at. Then next to that value is the filename which contains the configuration(s) for what devices you want mounted. We will call these filenames the "supplemental" files. Next to that value is the timeout which you want to occur after so many seconds of inactivity. The timeout will free or umount all devices specificed in the supplemental files after so many seconds of inactivity.

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