TK is a FORTRAN subroutine package that makes terminal interaction convenient. The primary calls are nodes which prompt the user and acquire data from the user. The nodes are organized into a tree which allows backwards movement, called jumping, so that the user can return to earlier nodes. TK supports typeahead which makes a TK program self-adjusting for both the novice and expert user alike. The novice may step through the program one node at a time, receiving prompts and explanations to entries on demand. The expert may issue whole strings of commands which are executed without the delay of prompts.
The TK I/O is done through UREAD[10] which supports command line input, indirect file input, generating script files for indirect input, and parameter substitution.
, Accept default value.
; End an indefinite list.
RETURN Use return to request an explanation.
\ Jump back one node.
\\ Jump back two nodes ( \...\) similarly defined).
\H Help (if it's been provided).
\n Jump to node number n (where n < the current level).
\aa Jump to the node named ``aa''.
\S Spawn a subprocess.
\X Exit from program.
\? Show these commands.
You may type ahead, e.g., if you know your responses to the next three
questions you may type them on one line separated by spaces.
TK will not prompt for entries supplied in advance. The type-ahead
buffer is 132 characters long. When you are at a node that has
several options, RETURN will list them. An option is selected
by entering a unique prefix of the prompt. If you respond to a prompt
with RETURN, an explanation will be given (assuming the
programmer has provided an explanation). You may accept a default (a
value in angle brackets) by responding with , (comma). Certain
nodes may allow entry of up to n items. Here the user indicates that
the list is complete by means of the indefinite list terminator
;. If the list terminator is required, ; appears in the
prompt within the first set of angle brackets. If a character string
entry contains ,;\, it must be enclosed in double quotes.