"Linux Gazette...making Linux just a little more fun!"

Welcome to installment 5 of Clueless at the Prompt: a new column for new users.

Getting Serious

If you've been experimenting with linux, reading all the docs you can get your hands on, downloading software to try, and generally cleaning up after the inevitable ill advised rm as root, you are probably starting to get enough confidence in linux to use it to do more than browse the internet. After all, why use Gates when you can jump the fences? This month I'm going to discuss some strategies for damage control, and how you can safely upgrade without losing valuable files and configurations, as well as some more general scouting around the filesystem.

Partitions as Safety Devices

If you have your entire linux installation on one partition, or partition, you could be putting your files and accmulated data in jeopardy as well as making the business of upgrading more difficult.

I understand that some distributions, notably Debian, are capable of upgrading any part of the system's component software without a full install, but I'm running Slackware, and it's generally recommended that when certain key system components are upgraded, a full reinstall is the safest way to avoid conflicts between old and new parts. What to do when the time comes can be much simpler if you have installed at least your /home direcory on a separate partition.

When you do a fresh install you are asked to describe mount points for your partitions. You are also asked if you want to format those partitions. If your /home directory doesn't contain much in the way of system files you can opt to skip formatting it, thereby reducing the chance that you'll have to use your backup to recover lost files in those directories. No, I'm not suggesting tht you don't have to backup your /home or other personal files, since there is no reliable undelete for linux that I'm aware of at this time. However, if you are just experimenting with linux and using a separate OS to do your important work and it's located on another disk, you may not feel to compelled to backup much in the way of linux files. Sooner or later though, if you are committed(or ought to be :) ) enough to linux to drop the other system, you WILL want to rethink that omission.

Formatting Floppies

When you format a floppy disk in MSDOS you do several operations in one fell swoop. You erase files, line up the tracks, sectors, etc, and install a MSDOS compatible filesystem. Another thing to recognize is that MS mounts the floppy drive as a device, while in linux the device is mounted as a part of the filesystem, to a specific directory.

There is a suite of utilities called mtools that can be used to create DOS formatted floppies, as well as some other MS specific operations, but I haven't had a lot of fun with it. I use the standard utilities instead Here is how I format a floppy disk:

     fdformat /dev/fd0xxx

where xxx is the full device name. My floppy drive is /dev/fd0u1440 but your mileage may vary. Try ls'ing your /dev directory to see. I installed from floppies, so I'm not real sure about CDROM installation but I took note of the drive specified to install the system. When the drive finishes formatting, you can type:

     mkfs -t msdos /dev/fd0xxxx

once again if necessary adding any specifiers. Your disk should be formatted.

Writing to your Floppy Disk

You are probably sitting there with a newly msdos formatted floppy disk and wondering how to write to it. If you use mtools, you are on your own, but don't feel bad you will save some steps, ie. mount and umount the floppy drive before and after writing to the drive, but it seems that I always fail to remember some option when I try to use mtools, so I don't use them. I type :

     mount -t msdos /dev/fd0xxxx /mnt

you can specify another mount point besides /mnt if you would like, perhaps a different mount point for each filesystem type that you might want to use, ext2, or minix for example, but if you or people that you work with use MS the msdos format might be the best, at least for now.

You can put an entry in your /etc/fstab that specifies the mount point for your floppy drive, with a line that looks something like:

     /dev/fd0         /mnt      msdos       rw,user,noauto  0   0 

This particular line will keep the floppy drive from mounting on bootup (noauto), and allow users to mount the drive. You should take the time to alert your users that they MUST mount and umount /dev/fd0 each time they change a disk, otherwise they will not get a correct ls when they try to read from the mount point. Assuming that this line is added to the /etc/fstab file the correct command for mounting the drive is:

     mount /dev/fd0

which will automatically choose /mnt as the mount point.To read from the drive, the present working directory must be changed by:

     cd /mnt

after which the contents of the disk can be read or written to> Linux is capable of reading files from several filesystem types, so it's a pretty good first choice, since you can share files with DOS users.

Anyway, assuming you didn't get any error messages, you are ready to copy a file to the disk using the:

     cp anyfile.type /mnt

assuming tha /mnt is the mount point that you specified in the mount command, you should have copied the file to your floppy disk. Try:

     ls /mnt

you should see the file you just cp'ed. if not, you should retry the mount command, but if you didn't get any error messages when you tried to mount the drive, you should be OK. To verify that you did write to the floppy instead of the /mnt directory, (there is a difference, if no drive is mounted it's just a directory) you can:

     umount /dev/fd0xxxx

and then try:

     ls /mnt

upon which you should get a shell prompt. If you get the file name that you tried to copy to floppy, merely rm it and try the whole routine again. If you find this confusing, read up on mtools by:

    info mtools

You may like what you see, give them a try. As I said I haven't had much luck with them, but basically the mformat command should do the abovementioned format tasks in one pass. Mcopy should likewise copy the named file to the floppy without the need to separately mount the drive.

Other Filesystems

There are several filesystems, as mentioned above that can be read by linux. Minix, ext2, ext, xiaf, vfat, msdos(I'm still a little bit foggy on the difference between these two).Still others can be read with the use of applications, amiga for instance. That's why it makes sense to split up what is a single step process in DOS.

Humbly acknowledging...

I got a lot of mail regarding the locate command, which I'm woefully guilty of spreading misinformation about. The real poop is that locate is a byproduct of a command, updatedb, which can be run at any time. It is run as default in the wee hours of the morning from /usr/bin/crontab, which is where I got the idea to leave the computer on overnight.

TTYL, Mike List