Linuxtutorial: Umount command - unmounting file systems

Working with Linux - First Things First

When you work as root

You have now installed Linux and the first thing you did was login as 'root'. Then you provided a password so that you and ONLY you could login to the system as 'root'. When you decide to work as root, you had better go into a phone booth first and change into a blue suit with a big 'S' on the front because 'root' is known as the 'superuser' (you can skip the red tights if you want).

That's really not meant to be just a witty reference to the Man of Steel. Actually, it is much more glamorous to be 'Superman' but root is actually more like the 'janitor' of the Linux system. Root has the keys to everything. He can shut off the lights, shut off the heat, lock you out of the building; he has to clean up the system and in the end make sure everything runs. And the most important thing about being a janitor - he sees everything.

'root' is not for routine work

As I mentioned, Linux makes your computer a true multi-user system, which means that besides root, you can and should work as another person. I say 'should' because doing routine work as 'root' could be hazardous to your health. When I first started using Linux myself, information was not all that readily available and I still had that 'one computer- one user' concept in my brain. It was after I had trashed all of the files and programs that make Linux run that I realized that working regularly as root wasn't a good idea.

Frequently Used Shell Commands

cd' command

To show the student the basic uses of the 'cd' command The first command you'll use is 'cd'. We talked about this in a previous lesson, so let's review the basics.

'cd' means 'change directory'.

The 'ls' command

To show the student the various variations of the 'ls' command 'ls' is another command that we've discussed a bit before. Let's go into some more detail.

Typing 'ls' will list the contents of a directory with just information about file names.

You can use 'ls a*' to list the names of all the files that begin with the letter 'a' and so on down through the alphabet. Please do not use the cuneiform alphabet unless you're from ancient Mesopotamia.

more' and 'less'

To introduce the student to these commands 'more' is a command that you can use to read, for example, what's written in that 'stuff' file that Tony sent you.

You would type 'more stuff' to see the jokes.

Press the 'q' key to stop viewing the file

Thursday, August 2, 2007

Umount command - unmounting file systems

Mounting file systems that aren't part of the standard Linux system is considered a temporary condition in Linux. Now that we know how to mount these outside file systems in Linux, the important thing now is to learn how to unmount it when we're finished using it.

In the early days of Linux, you could do serious damage to your system if you didn't unmount manually after you were finished. Nowadays if you have mounted a system and you shut down the computer without unmounting, the chances are pretty slim that you're going to trash a file system. Slim, however, isn't good enough for me. I'd rather not take a chance. I always take the time to unmount these external file systems when I'm finished with them.

The command for this is:

umount [/mount point]

In the examples I used in this lesson, the mount points were:

* floppy: /floppy - therefore umount /floppy
* CD: /cdrom - umount /cdrom
* Windows partition - umount /mnt

Remember also to NOT be accessing the floppy etc. when you use umount or it will give you a drive busy message. If you get this, you may have left a terminal open where you were using to copy or write to the particular drive. Check your terminals if you get this error.

I just wanted to point out another thing too. You are 'unmounting' but the command is umount (that is, without the N of un) Being u(n)familiar with the mount concept when I started with Linux, I typed unmount instead of umount and much to my surprise, I got the message: command not found. U(n)deniably, I had done something wrong. It took me a while to figure out that the command didn't include an N. I haven't really done a survey on how many people have actually done this. For all I know, I may be the only person who has, but I just thought it best to warn you.

Well, now you can use the standard devices that most PC users need. Later in our advanced class we'll talk about installing and using other devices like scanners, CD writers, Zip drives and matter/anti-matter flow inducers. (well, maybe we'll save that last one for the super-advanced classes!)

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'mv' command for renaming files

Let's go back yet again to Tony's file, 'stuff' again. 'stuff' is not a good name for a file just as 'book' isn't a good name for a book. Just imagine: "The number one bestselling book this week is 'Book' by John Author.

You should probably re-name this file to something meaningful. I would suggest doing something like this:

mv stuff tonys_jokes

The 'mkdir' command

mkdir' is the command for making directories. 'mkdir' may be familiar to MS-DOS users out there. As you have noticed, the people who wrote these programs tried to give them names that described what they do more or less, not as long as 'makemeadirectoryplease' and not too cryptic like 'xr77b'.

Using the 'mkdir' command

To create the directory 'my_friends' that we talked about in the last lesson, you would type:

mkdir my_friends

There are no whistles or buzzers. If you'd like some sort of acknowledgment, you could type

mkdir --verbose my_friends

and it will tell you that you created the directory.

The 'rm' command

cdrom	home	opt	tmp
dev	lib	proc	usr
bin	etc	lost+found		root	var
boot	floppy	mnt	sbin

Linuxtutorial

Working with Linux - First Things First

When you work as root

'root' is not for routine work

The basic directory structure in Linux

The /bin directory

The /etc directory

Frequently Used Shell Commands

cd' command

The 'ls' command

more' and 'less'

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