Korn Shell: Unix and Linux Programming Manual, Third Edition, The By Anatole Olczak
Table of Contents
Appendix E. Korn Shell Man Page
The KEYBD trap can be used to intercept keys as they are typed and change the characters that are actually seen by the shell. This trap is executed after each character (or sequence of characters when the first character is ESC) is entered while reading from a terminal. The variable .sh.edchar contains the character or character sequence which generated the trap. Changing the value of .sh.edchar in the trap action causes the shell to behave as if the new value were entered from the keyboard rather than the original value.
The variable .sh.edcol is set to the input column number of the cursor at the time of the input. The variable .sh.edmode is set to ESC when in vi insert mode (see later in this section) and is null otherwise. By prepending ${.sh.editmode} to a value assigned to .sh.edchar it will cause the shell to change to control mode if it is not already in this mode.
This trap is not invoked for characters entered as arguments to editing directives, or while reading input for a character search.
