GT.M - M Read Editing for Unix

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Overview

An editing capability similar to that available at the direct mode prompt has been added to the READ statement when reading from the $PRINCIPAL device if that device is a terminal. In addition to the functions currently available in direct mode, it is possible to select whether characters typed other than at the end of the current input will overwrite existing characters (overwrite mode) or be inserted at the cursor as is the case currently (insert mode.) Only the previous input may be recalled during a READ unlike the multiple lines available during direct mode.

The default EDITING and INSERT modes can be specified with an environment variable. Unless these features are enabled, the current functionality, which provides no line editing during M READ and insert mode during direct mode, will be retained.

Like the direct mode line editing functions, the proper functioning of editing for READ depends on setting the TERM environment variable to select a terminfo entry which matches the terminal (or terminal emulator) settings. There are some terminfo entries that may seem to work but which will fail to properly recognize function key sequences or fail to properly position the cursor in response to escape sequences from GT.M. GT.M itself does not have any knowledge of specific terminal functions. In some cases, new terminfo entries may need to be added. The terminfo man pages for the specific platform should be consulted for the details if this is needed. The terminal (emulator) manufacturer may be able to help.