directory. This is a safe, but not fail-safe, approach to deleting or recovering files. You may also be able to use the mc command, or Midnight Commander, discussed later in this chapter.

Creating Directories with the mkdir Command

The mkdir command can create one or several directories with a single command line. You may also be surprised to know that mkdir can also create a whole hierarchy of directories, which includes parent and children, with a single command line.

This command is one of the basic tools (along with cp and mv) you'll use to organize your information. Now, take a look at some examples. The following simple command line creates a single directory:

# mkdir temp

But you can also create multiple directories with

# mkdir temp2 temp3 temp4

You'd think that you could also type the following to make a directory named child under temp:

# mkdir temp/child

And you can, because the temp directory exists (you just created it). But, suppose you type

# mkdir temp5/child

mkdir: cannot make directory `temp5/child': No such file or directory

As you can see, mkdir complained because the temp5 directory did not exist. To build a hierarchy of directories with mkdir, you must use the -p, or parent option, for example:

# mkdir -p temp5/parent/child

# tree temp5

temp5

`-- parent

    `-- child



2 directories, 0 files

As you can see, mkdir created not only the temp5 directory, but also a subdirectory called parent, and a subdirectory under parent called child.

Now that you know how to create directories, take a look at how to remove them.

Removing Directories with the rmdir Command

The rmdir command is used to remove directories. To remove a directory, all you have to do is type

# rmdir tempdirectory

But there's a catch: the directory must be empty first! If you try to delete a directory with any files, you'll get an error message like this:

# rmdir temp5

rmdir: temp5: Directory not empty

In this example, temp5 also contains other directories. The rmdir command would also complain if a directory contains only files and not directories. You can use the rm command to remove the files first (remember to be careful if you use the -fr option), or you can move the files somewhere else, or rename the directory, with the mv command, discussed next.

The rmdir command, like mkdir, also has a -p, or parent, option. You can use this option to remove directory hierarchies, for example:

# rmdir -p temp5

rmdir: temp5: Directory not empty

Hmm. That didn't work! How about

# rmdir -p temp5/parent

rmdir: temp5/parent: Directory not empty

Hey! That didn't work either. Now try

# rmdir -p temp5/*

rmdir: temp5/parent: Directory not empty

This is getting frustrating! Try it one more time:

# rmdir -p temp5/parent/child

Finally! As you can see, you must specify the complete directory tree to delete it. If you use the same command line, but without the -p option, only the child directory would be deleted. But what if there are two or more subdirectories, for example:

# mkdir -p temp5/parent/child

# mkdir temp5/parent/child2

# tree temp5

temp5

`-- parent

    |-- child

    `-- child2



3 directories, 0 files

In order to delete the entire directory system of temp5, you'd need to use

# rmdir temp5/parent/*

So far, you've seen how to create and remove directories. Next, you'll learn about the mv command, which you can use to move or rename files and directories.

Renaming Files with the mv Command

The mv command, called a rename command but known to many as a move command, will indeed rename files or directories, but it will also move them around your file system.

Actually, in the technical sense, the files or directories are not really moved. If you insist on knowing all the gory details, read the Linux System Administrator's Guide, available through

http://sunsite.unc.edu/LDP/LDP/sag/index.html

In its simplest form, mv can rename files, for example:

# touch file1

# mv file1 file2

This command renames file1 to file2. However, besides renaming files, mv can rename directories, whether empty or not, for example:

# mkdir -p temp/temp2/temp3

# mv temp newtemp

Although mv has nine different options, this section concentrates on the two most commonly used. These options, -b and -i, allow you to use mv in a fairly safe way, because mv will not only rename, but overwrite silently and quickly! The first option, -b, creates a backup of any file or directory you rename to an existing name, for example:

# touch file1 file2 file3

# ls file*

file1  file2  file3

# mv file1 file2

# ls file*

file1 file2

As you can see, without using -b, mv not only renamed file1 to file2, but deleted file2 in the process. Is this dangerous? You bet! Now, try the -b option:

# touch file1

# ls file*

file1 file2 file3

# mv -b file1 file2

# ls file*

file2   file2~  file3

This example shows that although file1 has been renamed, replacing file2, a backup of file2 with a default extension of the tilde (~) has been created.