8.2 Non-ANSI Features

One feature of Clon that is beyond the ANSI standard is terminal autodetection (it requires an ioctl call and hence a foreign function interface). Terminal autodetection is used in several situations, for turning on highlighting automatically and for detecting a terminal line width.

If, for some reason, terminal autodetection is not available, Clon will work in so-called restricted mode. This means that --clon-highlight=auto won’t work (highlighting will not be turned on automatically on a tty). For the same reason, unless otherwise specified via either the COLUMNS environment variable or the --clon-line-width option, terminal output will be formatted for 80 columns regardless of the actual terminal width (see Global Control in The Clon End-User Manual).