unix:dup/2

Documentation
- Reference manual
- Packages
  - SWI-Prolog C-library
    - library(unix): Unix specific operations
      - fork/1
      - fork_exec/1
      - exec/1
      - wait/2
      - kill/2
      - pipe/2
      - dup/2
      - detach_IO/1
      - detach_IO/0
      - prctl/1
      - sysconf/1

Availability::- use_module(library(unix)).(can be autoloaded)

[det]dup(+FromStream, +ToStream)

Interface to Unix dup2(), copying the underlying filedescriptor and thus making both streams point to the same underlying object. This is normally used together with fork/1 and pipe/2 to talk to an external program that is designed to communicate using standard I/O.

Both FromStream and ToStream either refer to a Prolog stream or an integer descriptor number to refer directly to OS descriptors. See also demo/pipe.pl in the source-distribution of this package.