Creating New Directories

* Make a new directory with a subdirectory using the ?p option:

Deleting Directories

The rmdir (remove directory) command is used to delete an empty directory.  The directory to be deleted can be referenced via an absolute path or via a relative path starting with the current working directory.  The following are some examples of each method:

$ rmdir /home/tclark/new_dir1
$ ls

examples  new_dir2  new_dir3

$ rmdir new_dir2
$ ls

examples  new_dir3

A directory cannot be removed with the rmdir command unless it is completely empty.  To remove a directory and it's contents you can use the rm ?r command which will be covered later in this chapter.  Be careful with this as you can easily delete more than you had intended!

Renaming directories

Directories can be renamed with the mv command.  Here's an example of renaming a directory:

$ mv new_dir3 another_dir
$ ls

examples  another_dir

The mv command can also be used to move a directory to another location.  This will be covered more later in this chapter when we talk about moving and renaming files.

Navigating the Directory Tree

The cd (change directory) command is used to change from one directory to another.  As with creating and deleting directories, it is possible to change to another directory by using either an absolute path or by using a relative path referenced from the current working directory.

There are also some special shortcuts that can be used with the cd command.  For instance, .. refers to the parent directory of the current working directory, ~ refers to the home directory of the current user and - refers to the last directory from which the user changed.  The following are some examples of directory navigation. 

To demonstrate this without having to type pwd after each cd we have added the working directory to the prompt on a separate line.

$ PS1="Directory:\w\n\\$ "
Directory:/usr/bin
$ cd /usr/bin                
Directory:/usr/bin
$ cd       
Directory:~
$ cd /
Directory:/
$ cd ~                 
Directory:~
$ cd examples                
Directory:~/examples
$ cd /tmp
Directory:/tmp
$ cd -
/home/tclark/examples
Directory:~/examples
$ cd /home/tclark
Directory:~

You might have noticed that the second cd command had no directory listed.  This will take you back to your home directory from anywhere.  This is the exact same result as the cd ~ command.  It is also worth mentioning that when we used the cd ? combination to take us to the previous directory it printed the current directory before returning us to the previous one.

Listing Directory Contents

The ls command is used to list the contents, subdirectories and files, within a directory.  There are several options to the ls command that determine both the content and order of the listing displayed.  Without specifying any options, ls displays subdirectory and file names.

$ cd ~/examples
$ ls
declaration.txt  gettysburg.txt  preamble.txt

Table 4.2 contains descriptions of some of the options that are commonly used to display additional information:

Table 4.2: ls Command Options

The following are some examples of the ls command using the above options:

$ cd ~/examples
$ ls
declaration.txt  gettysburg.txt  preamble.txt
$ ls -al
total 20
drwxrwxr-x    2 tclark   tclark       4096 Jan 13 17:48 .
drwx------    4 tclark   tclark       4096 Jan 13 18:29 ..
-rw-rw-r--    1 tclark   tclark       2230 Jan 13 17:47 declaration.txt
-rw-rw-r--    1 tclark   tclark       1310 Jan 13 17:48 gettysburg.txt
-rw-rw-r--    1 tclark   tclark        360 Jan 13 17:48 preamble.txt
$ ls -alt
total 20
drwx------    4 tclark   tclark       4096 Jan 13 18:29 ..
drwxrwxr-x    2 tclark   tclark       4096 Jan 13 17:48 .
-rw-rw-r--    1 tclark   tclark        360 Jan 13 17:48 preamble.txt
-rw-rw-r--    1 tclark   tclark       1310 Jan 13 17:48 gettysburg.txt
-rw-rw-r--    1 tclark   tclark       2230 Jan 13 17:47 declaration.txt