Pseudo-devices

This page applies to Harlequin v13.1r0 and later; both Harlequin Core and Harlequin MultiRIP.

The five device names %stdin%, %stdout%, %stderr%, %statementedit%, and %lineedit% are handled specially. They do not identify actual devices but can be treated as if they do when opening files on them. They are not mounted as devices and are not directly associated with a device type. They are collectively called pseudo-devices; they behave like non-relative devices.

The error handler writes its error messages to a file opened on %stdout% (note: not %stderr% ); the executive reads its input from a file opened on %stdin% via files opened on %lineedit% and %statementedit%. The core RIP writes details of unexpected conditions, especially during the bootstrap process, to a file opened on %stderr%.

The two pseudo-devices %lineedit% and %statementedit% are only used to filter interactive input for the executive. Had they not been invented in the days of Level 1 PostScript language, they would probably have been treated as filters. They are not discussed further here.