Emacs as Your IDE

This is a no-frills listing towards using Emacs as a development environment. C-x means CTRL-x. M-x means ALT-x (or ESC and then x).

You can press the TAB key almost anywhere for autocompletion. Wherever you input text, use M-p and M-n to traverse up and down the history list.

C-u is the numeric-prefix operator. To go up by 10 lines, for example, one would say C-u 10 C-p.

Stuck!

Exit Emacs: C-x C-c
Cancel command: C-g

File Handling

Open a file: C-x C-f (Remote file: /user@host:path/to/file via ftp)
Change to a directory: C-x d
Save file: C-x C-s
Save as: C-x C-w
Close a file (kill buffer): C-x k
Reload file: C-x C-v
Change to another open file: C-x b
List all open files (buffers): C-x C-b
Maximise a window: C-x 1
Switch to the other window: C-x o

Editing

Start marking: C-<SPACE> (Use arrow keys to select region)
Cut: C-w
Copy: M-w
Paste: C-y (previous: M-y)
Undo: C-x u
Delete word: M-d
Complete word: M-/
Open a new line: C-o
Kill upto end of line: C-k (Is appended to clipboard)
Indent current line to GNU C standard: <TAB>
Toggle read-only: C-x C-q
Paragraph-ise current region: M-q
Spell-check current word: M-$ (whole file: M-x ispell)

Search/Replace

Search forward: C-s (Press C-s to search again)
Search backward: C-r
Search and replace: M-%
List occurrences: M-x occur
Run grep: M-x grep
Reg-ex search: C-M-s

[XKCD pays tribute to Emacs]

Navigation

Beginning of file: M-<
End of file: M->
Beginning of line: C-a
End of line: C-e
Previous word: M-b
Next word: M-f
Previous matching bracket: C-M-b (if it doesn't work, try ESC followed by C-b)
Next matching bracket: C-M-f (or ESC C-f)
Outline mode: C-u 1 C-x $ (C-x $ to revert)
Go to line: M-g (or M-x goto-line)

The arrow area is so far away!?
Previous line: C-p
Next line: C-n
Previous character: C-b
Next character: C-f
Page Up: M-v
Page Down: C-v

Vertical Copy

Sometimes you will need to copy a vertical patch of data, e.g. one column in a table. First press C-<space> where you want to start copying. Then go to the end of the column and press C-x r k. To paste the column press C-x r y. (If you don't want to delete original column, just press C-_ there once to restore it and then press C-x r y at target.)

Registers

To save the current location in register a: C-x r <SPC> a
To jump to the location in register a: C-x j a
To list saved registers: C-x r l

Symbol Lookup

Assuming CODEDIR to be the top-level source directory, first update your ~/.bashrc like so:

alias mktags='cd $CODEDIR && etags `find $CODEDIR -name "*.[h|c]"` && cd -'

Then run:

source ~/.bashrc
mktags

When Emacs asks for the TAGS file, specify $CODEDIR/TAGS.

Go to function/variable definition: M-. (M-* to return)
Next definition of the tag: C-u M-. (e.g. same method in multiple classes)
Search for occurrences of symbols: M-x tags-search (M-, to search forward)
Find symbols as reg-exps: M-x find-tag-regexp
Autocomplete symbol: M-<TAB>

Re-run mktags when the codebase has changed drastically.

Compilation and Debugging

Compile: M-x compile
Stop compilation: C-c C-k
Go to next error: C-x `
Go to source line giving the error: C-c C-c
Debug with GDB: M-x gdb
Insert breakpoint: C-x <SPACE>
Run a shell command: M-! (C-u M-! to insert output)
Open a shell: M-x shell

To change the default string for M-x compile, edit your ~/.emacs file:

(setq compile-command "gmake -f Makefile.gnu all")

Comparing Two Files

Start a diff session: M-x ediff
Next match: n
Previous match: p
Copy from file A to B: a
Copy from file B to A: b
Save file X: wX
See diff output: D
Ignore whitespace differences: ##
Compare directories: M-x ediff-directories

Keyboard Macros

Begin recording: C-x (
End recording: C-x )
Execute macro: C-x e

Example: Add 'extern' before all function protoypes in a file.

Go to the first prototype, and say:

    C-x (
    C-a
    extern<SPACE>
    C-n
    C-x )

Then say C-u 50 C-x e to replace 50 prototypes.

Perforce CVS Integration

Get p4.el and then follow these steps.

$ emacs -batch -f batch-byte-compile p4.el

Put the p4.el in some directory, say /home/foo/bar. Then edit your ~/.emacs as follows:

(setq load-path (cons "/home/foo/bar" load-path))
(load-library "p4")

You should see a P4 menu in Emacs, and you can do CVS operations from within Emacs now.

Symbol Lookup with cscope

Download cscope program, and xcscope.el and cscope-indexer from an OSS repository. Save the xcscope.el onto some directory in Emacs' load-path. Edit your ~/.emacs as follows:

(require 'xcscope)

To add a directory ~/foo to your load-path, use the following directive in .emacs file, making sure it appears before the "require xcscope" directive:

(setq load-path (cons "~/foo" load-path))

Place cscope-indexer in your $PATH. You can then use these keystrokes while browsing C source code:

Index files: C-c s I
Find global definition: C-c s d
Find symbol definition: C-c s s
Find this file: C-c s f
Find functions calling this function: C-c s c
Find functions called by this function: C-c s C
Find this pattern: C-c s e
Find this text string: C-c s t
Find files including this file: C-c s i

File Operations

Operations such as move, copy, delete etc. are available in the directory editor: M-x dired