What are the common Control combinations in a terminal setting

Question

I would like to have a good guide to the common Control key combinations in use in bash (and similar) shells and the combinations used by common programs in use in those shells.

My particular motivation is to be able to run GNU screen on one computer, ssh to a second computer and use screen and irssi on that computer. So I need to use something other than Ctrl-A to control one of the screen sessions. So I need to know what are Control key combinations are safe to use.

But I imagine this list would be useful for others who want to bind custom actions to Control key combinations.

I reckon we'd be best to group the Control key combinations by application (eg. bash itself, screen, vim, emacs), to make it easy to spot the applications you use or can ignore. So please one application per answer - hope that works.

Answer 1

Bash itself uses the GNU readline library, as do many other interactive command-line programs. Readline has the following default key bindings which mimic emacs behaviour:

Moving about on the line:

• Ctrl + A Go to the beginning of the line you are currently typing on
• Ctrl + E Go to the end of the line you are currently typing on

Editing text on the line:

• Ctrl + U Clears the line before the cursor position. If you are at the end of the line, clears the entire line.
• Ctrl + H Same as backspace
• Ctrl + W Delete the word before the cursor
• Ctrl + K Clear the line after the cursor
• Ctrl + T Swap the last two characters before the cursor
• Esc + T Swap the last two words before the cursor

Other:

• Ctrl + L Clears the Screen, similar to the clear command
• Ctrl + R Let’s you search through previously used commands
• Ctrl + C Kill whatever you are running
• Ctrl + D Exit the current shell
• Ctrl + Z Puts whatever you are running into a suspended background process. fg restores it.

Answer 2

Vim uses:

• Ctrl-B back (up) one screen
• Ctrl-D down half screen
• Ctrl-E scroll text up (cursor doesn't move unless it has to)
• Ctrl-F foreward (down) one screen
• Ctrl-G show status
• Ctrl-H backspace
• Ctrl-J line down
• Ctrl-L refresh screen
• Ctrl-N move down one line (or scroll forward through autocompletions)
• Ctrl-P move up one line (or scroll backward through autocompletions)
• Ctrl-R redo (after undo)
• Ctrl-T go to the file/code you were editing before the last tag jump
• Ctrl-U up half screen
• Ctrl-V enter visual block mode
• Ctrl-W used for managing split windows
• Ctrl-Y scroll text down (cursor doesn't move unless it has to)

Answer 3

Emacs uses everything. From http://www.cs.rutgers.edu/LCSR-Computing/some-docs/emacs-chart.html :

• C-SP set-mark-command
• C-a beginning-of-line
• C-b backward-char
• C-c exit-recursive-edit
• C-d delete-char
• C-e end-of-line
• C-f forward-char
• C-g (not explicitly mentioned in the link above, but used as a 'cancel' when entering commands)
• C-h help-command
• C-i (TAB) indent-for-tab-command
• C-j (LFD) newline-and-indent
• C-k kill-line
• C-l recenter
• C-m (RET) newline
• C-n next-line
• C-o open-line
• C-p previous-line
• C-q quoted-insert
• C-r isearch-backward
• C-s isearch-forward
• C-t transpose-chars
• C-u universal-argument
• C-v scroll-up
• C-w kill-region
• C-x Control-X-prefix
• C-y yank
• C-z suspend-emacs
• C-] abort-recursive-edit
• C-_ undo

Answer 4

It seems that Ctrl+Q would be an ideal escape key for GNU screen, is there a reason that nobody seems to suggest it?

The only downside I can think of is that on Mac OS X Command+Q is the keyboard shortcut for quitting an application which would be slightly dangerous if confused with Ctrl+Q.

Otherwise, from the current answers and my own research it seems that nothing conflicts with Ctrl+Q.

Answer 5

Lots of application uses the GNU readline library, so those keybindings are good to know about. You can study them in the readline(2) manual page, easily viewed here:
http://linux.die.net/man/3/readline

Answer 6

GNU screen by default uses Ctrl-A as its command key.