Acknowledgement

This tutorial is essentially the same as one developed at the Mathematics Department at University of Utah. Only some very minor changes have been made.

Lesson 3: Creating and using directories

After working on your unix system for a while you will accumulate many files. Just like an unorganized desk, this creates a mess in which it is hard to work. The solution is to create directories in which to store related items. A directory is like a file folder which contains related documents (your files). As an example, suppose that when you list your files you see this:

  % ls
  fred1 fred2 fred3 ch1 ch2 ch3 foo.c bar.c
  %

This is really not badly organized: the files fred1, etc. are letters to fred, the files ch1, etc. chapters of a book, and foo.c, bar.c are C programs. Nonetheless, we decide that it is time to get organized, with one directory per project.

Please create files with the names listed above in order to be able to complete this lesson. You can use the touch command, the cat command or an editor such as vi. Their content is irrelevant -- even empty files are sufficient.

The mdkir command.

We create a new directory using the mkdir command ( m ake d irectory).

  % mkdir letters
  % ls
  fred1 fred2 fred3 ch1 ch2 ch3 foo.c bar.c letters

Notice that the directory letters shows up in the listing. If you are not sure what is a file and what is a directory, try this:

  % ls -F
  fred1 fred2 fred3 ch1 ch2 ch3 foo.c bar.c letters/

Notice that letters is displayed somewhat differently.

The mv command

Now we move the letters into the directory letters using the mv command ( m o v e).

  % mv fred1 fred2 fred3 letters
  % ls
  ch1 ch2 ch3 foo.c bar.c letters

If we want to check that letters really contains the files it should, we do this:

  % ls letters
  fred1 fred2 fred3

There is, by the way, a useful shortcut:

  % mv fred* letters

Here the character * matches any sequence of characters, including the null string. Thus files named fred, fred101, and freddy would all be moved into letters.

Paths

You can deal directly with files in a directory like this:

  % cat letters/fred1

This command displays the contents of the file fred1 , which is in the directory letters. Here are some other ways of doing the same thing:

  % cat letters/fred1
  % more letters/fred1
  % emacs letters/fred1

We could even do this:

  % cat l*f*1

Changing directories with cd

Sometimes it is better to work inside the directory letters. To do it we use the cd command ( ch hange d irectory).

  % cd letters
  % ls
  fred1 fred2 fred3

The letters are there, as they chould be. To go back to our home directory we do this:

  % cd

We check that our home directory contains what it should.

  % ls
  ch1 ch2 ch3 foo.c bar.c letters

Now we make directories for the other files and move them into the right places:

  % mkdir book; mv ch* book
  % mkdir cprogs; mv *.c cprogs
  % ls -F
  book/ cprogs/ letters/
  % ls book
  ch1 ch2 ch3
  %

Where are we?

Sometimes in moving from one directory to another we lose track of where we are. To find out what the current directory is, use the pwd command ( p rint w orking d irectory).

  % pwd
  jeremy
  % cd book
  % pwd
  jeremy/book
  %

Removing directories

To remove a directory we first remove all the file in it, then remove the directory with rmdir ( r emove d irectory).

  % pwd
  jeremy
  % cd letters
  % pwd
  jeremy/letters
  % rm *
  % cd ..
  % rmdir letters

The command rm * removes all files in the current directory. The command cd .. changes the current directory to the parent of the current one. In this case, it changes us from jeremy/letters to jeremy. Remember that jeremy/letters is a path , as is jeremy/letters/fred1. The latter is the path which starts with Jeremy's home directory and ends with the file fred1.

Back to the lab main page