To explore Unix and its capabilities, you’ll need to move around among the directories. You do so using the cd command, which takes you from the directory you’re currently in to one that you specify. Code Listing 1.4 illustrates how you use cd to change directories.
[jdoe@frazz jdoe]$ cd / [jdoe@frazz /]$ cd [jdoe@frazz jdoe]$ cd /home/jdoe/Project/ [jdoe@frazz Project]$ cd /etc [jdoe@frazz etc]$ cd /home/jdoe/ [jdoe@frazz etc]$ cd /home/jdoe/mail/ [jdoe@frazz mail]$ cd .. [jdoe@frazz jdoe]$ |
1. | cd Projects To move to a specific directory, type cd plus the name of the directory. In this example, we move down in the directory tree to a subdirectory called Projects. (See the Moving Up and Down sidebar for an explanation of what “up” and “down” mean in Unix terms.) |
2. | cd .. Type cd .. to move up one level in the directory tree. |
3. | cd /etc Here, /etc tells the system to look for the etc directory located at the system root. |
Moving Up and DownThroughout this book, we’ll talk about moving “up” and “down” through the Unix file system. Moving “up” means moving into the directory that contains the current directory—that is, closer to the root directory. Moving “down” means moving into subdirectories that are contained by the current directory—that is, farther from the root directory. |
✓ Tips
If you don’t remember the name of the directory you want to change to, you can use ls to list the directories and files in your current directory, then use cd as shown above. See the previous section, Listing Directories and Files with ls, for more information.
You can return to your home directory from anywhere in the Unix system by entering cd without specifying a directory.
You can often use a tilde (~) as a handy shortcut to your home directory. For example, if you want to change to the Urgent directory within the Projects directory in your home directory, you could use something like cd /home/users/ y/yourid/Projects/Urgent or just use the shortcut cd ~/Projects/Urgent
Keep in mind that your home directory isn’t the same as the system root directory. You might think of your home directory as “the very small section of the Unix system that I can call my own.” Every person using the Unix system has his or her own little personal section.
The current directory is always indicated with a ., while the next higher directory (the one that contains the current directory) is indicated with .. That is why you use cd .. to move up a directory. In Chapter 10, you will see a specific use for . to specify the current directory when running scripts or programs.
Visit Chapter 2 for much more about directories and files.