I$Dup modified by Lothan

Lothan — Fri, 27 Jun 2014 23:18:34 -0000

Duplicate Path
Returns a synonymous path number

OS9 I$Dup 103F 82

Entry Conditions

A old path number (number of path to duplicate)

Exit Conditions

A new path number (if no error)

Error Output

CC carry set on error

B error code, if any

Additional Information

The Duplicate Path returns another, synonymous path number for the file or device specified by the old path number.
The shell uses the Duplicate Path call when it redirects I/O.
System calls can use either path number (old or new) to operate on the same file or device.
Makes sure that no more than one process is performing I/O on any one path at the same time. Concurrent I/O on the same path can cause unpredictable results with RBF files.
The I$Dup call always uses the lowest available path number. This lets you manipulate standard I/O paths to contain any desired paths.

Recent changes to I$Dup