Bashscripts.org

The auto complete feature of the Bourne Again SHell makes bash one of the most loved and newbie-friendly Linux shells. Just by pressing the Tab key you can complete commands and filenames. Press the Tab key twice and all files in the directory get displayed. But you can do more with autocomplete -- such as associating file types with applications, and automatically designating whether you're looking for directories, text, or MP3 files. With simple commands such as complete and the use of Escape sequences, you can save time and have fun on the command line.

You can use the dollar sign ($), tilde (~), and at (@) characters along with the Tab key to get quick results in autocomplete.

For instance, if you want to switch to the testing subdirectory of your home directory, you can either type cd /ho[Tab]/tes[Tab] to get there, or use the tilde -- cd ~tes[Tab]. If the partial text -- that is, the portion before you press Tab -- begins with a dollar sign, bash looks for a matching environment variable. The tilde tells bash to look for a matching user name, and the at-sign tells it to look for a matching hostname.

Escaping is good

The Tab key can complete the names of commands, files, directories, users, and hosts. Sometimes, it is overkill to use the Tab key. If you know that you are looking for a file, or only user names, then use the Escape key instead for completion, as it limits bash's completion field.

You can use several Escape key combinations to tell bash what you are looking for. Invoke Escape key combinations by pressing a key while keeping the Escape key pressed. When looking for a file, you can use the Esc-/ (press / along with Escape) key combination. This will attempt filename completion only. If you have one file and one directory beginning with the letter 'i,' you will have to press the Tab key twice to see all the files:

$ less i <tab><tab>
ideas im articles/

When you type less i and press '/' while keeping the Escape key pressed, bash completes the filename to 'ideas.'

While Control key combinations work no matter how long you keep the Ctrl key pressed before pressing the second key, this is not the case with Escape key sequences. The Esc-/ sequence will print out a slash if you delay in pressing the / key after you press the Escape key.

You can also use Escape along with the previously discussed $, ~, and @ keys. Esc-$, for example, completes only variable names. You can use Esc-! when you wish to complete command names. Of course you need to press the Shift key in order to use any of the "upper order" characters.