If standard input is a terminal device, MDB provides some simple emacs-style facilities for editing the command line. The search, previous, and next commands in edit mode provide access to the history list. Only strings, not patterns, are matched when searching. In the list below, the notation for control characters is caret (^) followed by a character shown in upper case. The notation for escape sequences is M- followed by a character. For example, M-f (pronounced meta- eff) is entered by depressing <ESC> followed by 'f', or by depressing Meta followed by 'f' on keyboards that support a Meta key. A command line is committed and executed using RETURN or NEWLINE. The edit commands are:
Move cursor forward (right) one character.
Move cursor forward one word.
Move cursor backward (left) one character.
Move cursor backward one word.
Move cursor to start of line.
Move cursor to end of line.
Delete current character, if the current line is not empty. If the current line is empty, ^D denotes EOF and the debugger will exit.
(Meta-backspace) Delete previous word.
Delete from the cursor to the end of the line.
Reprint the current line.
Transpose current character with next character.
Fetch the next command from the history. Each time ^N is entered, the next command forward in time is retrieved.
Fetch the previous command from the history. Each time ^P is entered, the next command backward in time is retrieved.
Search backward in the history for a previous command line containing string. The string should be terminated by a RETURN or NEWLINE. If string is omitted, the previous history element containing the most recent string is retrieved.
The editing mode also interprets the following user-defined sequences as editing commands. User defined sequences can be read or modified using the stty(1) command.
User defined erase character (usually ^H or ^?). Delete previous character.
User defined interrupt character (usually ^C). Abort the current command and print a new prompt.
User defined kill character (usually ^U). Kill the entire current command line.
User defined quit character (usually ^\). Quit the debugger.
User defined suspend character (usually ^Z). Suspend the debugger.
User defined word erase character (usually ^W). Erase the preceding word.
Fetch the previous command from the history (same as ^P).
Fetch the next command from the history (same as ^N).
Move cursor backward one character (same as ^B).
Move cursor forward one character (same as ^F)