CS 497C – Introduction to UNIX Lecture 18: - The GNU emacs Editor

1. CS 497C – Introduction to UNIXLecture 18: - The GNU emacs Editor Chin-Chih Changchang@cs.twsu.edu

2. Deleting, Moving and Copying Text • To delete a character, use [Ctrl-d]. To delete a word, use [Alt-d]. • To delete text from the current cursor position to the end of line, use [Ctrl-k]. • To delete the entire line, first use [Ctrl-a] and then [Ctrl-k][Ctrl-k]. • To delete text in a region, first mark the region and then use [Ctrl-w].

3. Deleting, Moving and Copying Text • [Ctrl-y] is universally used to restore text from the deletion. • While [Ctrl-w] deletes text in a region, the command to copy text is [Alt-w]. • You can transpose two adjacent characters by using [Ctrl-t].

4. Changing Case of Text • To convert an entire word to uppercase, move to the beginning of the word and then press [Alt-u]. • You use [Alt-u] for converting a word to lowercase. • To capitalize a single character, position the cursor under it and then use [Alt-c].

5. Changing Case of Text and Command Completion • For transforming case in large blocks of text, use a region. The commands to convert text in a region are: [Ctrl-x][Ctrl-u] and [Ctrl-x][Ctrl-l]. • The command completion feature can reduce some of the typing work. • The guiding principle here is this: Enter as much of the command text as you want and then press the [Tab] key.

6. Undoing and Redoing Editing • To undo the change, there are three ways: [Ctrl-x]u, [Ctrl-_],[Ctrl--]. • If you continue to press [Ctrl--], you’ll undo the changes made before the last save. • If you keep pressing [Ctrl--], emacs starts redoing everything that you have undone.

7. String Search • The incremental and non-incremental search techniques are used in string search in emacs. • Incremental search is invoked with [Ctrl-s] followed by the search string. • After entering [Ctrl-s]emacs prompts for the search string in the minibuffer. Suppose you’re looking for mail. After m is entered, the search starts immediately.

8. String Search • The cursor relocates itself at the first instance of m – maybe on the word moon. • After mail is entered, press [Enter]. • There are a number of advantages of using incremental search: • The search is faster. • emacs tells you instantly whether the string exists in the file. • If there is a typo, backspacing erases the error.

9. String Search • At the end of a file, use [Ctrl-r] instead of [Ctrl-s]. • To repeat a search, you’ll have to use the same command – [Ctrl-s] or [Ctrl-r]. • In non-incremental search just press [Enter] and then type the string. • Like vi, emacs uses a pattern comprising some special characters to look for similar strings. This pattern is called a regular expression.