plan9 man page for dup

DUP(3)							     Library Functions Manual							    DUP(3)

NAME
       dup - dups of open files

SYNOPSIS
       bind #d /fd

       /fd/0
       /fd/1
       ...

DESCRIPTION
       The  dup  device  serves a one-level directory containing files whose names are decimal numbers.  A file of name n corresponds to open file
       descriptor n in the current process.

       An open(2) of file n results in a file descriptor identical to what would be returned from a system call dup(n, -1).  Note that the  result
       is no longer a file in the dup device.

       The  stat operation returns information about the device file, not the open file it points to.  A stat of #d/n will contain n for the name,
       0 for the length, and 0400, 0200, or 0600 for the mode, depending on whether the dup target is open for reading, writing, or both.

SEE ALSO
       dup(2)

SOURCE
       /sys/src/9/port/devdup.c

																	    DUP(3)