---

1.8.2 Terminal Input

The most important limitation of a terminal is its input capabilities. On a workstation with function keys and independent control, meta, and shift modifiers, it is possible to type 800 or so distinct single keystrokes. Although by default, Hemlock uses only a fraction of these combinations, there are many more than the 128 key-events available in ASCII.

On a terminal, Hemlock attempts to translate ASCII control characters into the most useful key-event:

• On a terminal, control does not compose with shift. If the control key is down when you type a letter keys, the terminal always sends one code regardless of whether the shift key is held. Since Hemlock primarily binds commands to key-events with keysyms representing lowercase letters regardless of what bits are set in the key-event, the system translates the ASCII control codes to a keysym representing the appropriate lowercase characters. This keysym then forms a key-event with the control bit set. Users can type C-c followed by an uppercase character to form a key-event with a keysym representing an uppercase character and bits with the control bit set.
• On a terminal, some of the named keys generate an ASCII control code. For example, Return usually sends a C-m. The system translates these ASCII codes to a key-event with an appropriate keysym instead of the keysym named by the character which names the ASCII code. In the above example, typing the Return key would generate a key-event with the Return keysym and no bits. It would NOT translate to a key-event with the m keysym and the control bit.

Since terminals have no meta key, you must use the Escape and C-Z modifier-prefix key-events to invoke commands bound to key-events with the meta bit or meta and control bits set. ASCII terminals cannot generate all key-events which have the control bit on, so you can use the C-^ modifier-prefix. The C-c prefix sets the hyper bit on the next key-event typed.

When running Hemlock from a terminal ^\ is the interrupt key-event. Typing this will place you in the Lisp debugger.

When using a terminal, pop-up output windows cannot be retained after the completion of the command.