DUP(3)                                                     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 corre-
          sponds 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

     Page 1                       Plan 9            (printed 10/29/25)