2.3 Command-line editing

Gforth maintains a history file that records every line that you type to the text interpreter. This file is preserved between sessions, and is used to provide a command-line recall facility; if you type Ctrl-P repeatedly you can recall successively older commands from this (or previous) session(s). The full list of command-line editing facilities is:

• Ctrl-p (“previous”) (or up-arrow) to recall successively older commands from the history buffer.
• Ctrl-n (“next”) (or down-arrow) to recall successively newer commands from the history buffer.
• Ctrl-f (or right-arrow) to move the cursor right, non-destructively.
• Ctrl-b (or left-arrow) to move the cursor left, non-destructively.
• Ctrl-h (backspace) to delete the character to the left of the cursor, closing up the line.
• Ctrl-k to delete (“kill”) from the cursor to the end of the line.
• Ctrl-a to move the cursor to the start of the line.
• Ctrl-e to move the cursor to the end of the line.
• <RET> (Ctrl-m) or <LFD> (Ctrl-j) to submit the current line.
• <TAB> to step through all possible full-word completions of the word currently being typed.
• Ctrl-d on an empty line line to terminate Gforth (gracefully, using bye).
• Ctrl-x (or Ctrl-d on a non-empty line) to delete the character under the cursor.

When editing, displayable characters are inserted to the left of the cursor position; the line is always in “insert” (as opposed to “overstrike”) mode.

On Unix systems, the history file is ~/.gforth-history by default¹. You can find out the name and location of your history file using:

     history-file type \ Unix-class systems
     
     history-file type \ Other systems
     history-dir  type

If you enter long definitions by hand, you can use a text editor to paste them out of the history file into a Forth source file for reuse at a later time.

Gforth never trims the size of the history file, so you should do this periodically, if necessary.