Frequently Used Shell Commands

If you install a window manager like KDE, you can copy, delete, move and rename files by way of a graphic user interface like Konqueror. But as I mentioned before, shell commands are pretty standard in Linux, so we're going to teach you the ones that you're most likely to use. You can use them both in text mode or in your x-terminal when you're in graphics mode.

'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'.

Typing: cd /[directory name] will get you into one of the main directories in Linux.

Typing cd .. will get you out of it.

Typing cd without the / and a sub-directory name will get into that subdirectory.

Remember, you don't have to type the whole name

Typing: 'cd' and the first letter or letters of a directory and the TAB key will complete it for you. Then all you have to do is press enter.

If you type just: cd

you'll go back to your home 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.

Normally we'll want to add on some parameters (those -[letter] combinations) so that we'll get some more detail

Using 'ls -l'

To show the student how to get some more detail with 'ls -l' 'ls -l' will get you a detailed listing of the directory like this.

-rw-r--r--

1 bob

users

103824

Jul 10 12:01

waikiki.jpg

The first part, those letter, are file permissions. We'll go into that in a later lesson. That basically shows what you and others are allowed to do with the file, like read it, modify it or make nasty comments about it.

The next one shows that you've got 1 file. The next one that it belongs to you, 'bob'. The next one represents that Linux, not only recognizes users, but also groups of users. We'll go into that in the next course. The numbers are the size of the file in bytes. You have the date and when it was created or modified or copied there. Lastly, you have the name of the file, waikiki.jpg, which is obviously your important tax records.

'ls -l' will give you a detailed listing in alphabetical order, starting with any file that begins with a number, then any file that begins with a capital letter and then any normal file that begins with a lowercase letter. So if you have a file '007_secrets.txt' that'll be the first one you see.

Other parameters with 'ls'

Now let's add some more parameters on

'ls -l -t' will give you a listing according to the time with the newest ones appearing first in the list. You don't need to separate the parameters either. 'ls -l -t' and 'ls -lt' are the same thing. If you want the oldest to appear first, try:

'ls -ltr'

The 'r' is for reverse order.

There are a couple of parameters in capitals that you may want to use. 'ls -lS' will list your files from biggest to smallest. 'ls -lSr' will reverse this order.

'ls -lX' will list files according to type in alphabetical order. If you have any that end in *.zip, then those will be last. If you want those to be first, now you know: 'ls -lXr'

There is also a parameter that will help you if you want to find out more about these commands or any others. 'ls --help' will give you details of all the possible variations for this command.

The 'file' command

Linux is also color coded, as you know, so once you get used to the colors, you'll know what the file is about. Let's say your friend Tony, the one with the magic markers, sends you a file he says is really neat. It's attached to an e-mail message and it says 'stuff'. You can see what type of file it is by typing:

'file stuff'

You may see something like this:

'stuff: ASCII text'

This means that the file contains plain text. It's probably some jokes or his favorite chili recipe.

If you don't know what some particular file contains and you're curious about it, you can use this command to get some information about the file.

'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

It's useful for this, but not really ideal. We'll talk more about 'more' in this lesson when we use it in combination with other commands

'less' is better for viewing files. You can scroll back up to see the whole text if you want. You can't do that with 'more'. 'less' is more than 'more', if you get my meaning.

type

'less stuff'

Again, press the 'q' key to stop viewing the file

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