man.postnix Miscellaneous man pages of Plan 9 related material

     DUP(3)                                                     DUP(3)

     NAME
          dup - duplicate an open file descriptor

     SYNOPSIS
          #include <u.h>
          #include <libc.h>

          int dup(int oldfd, int newfd)

     DESCRIPTION
          Given a file descriptor, oldfd, referring to an open file,
          dup returns a new file descriptor referring to the same
          file.

          If newfd is -1 the system chooses the lowest available file
          descriptor.  Otherwise, dup will use newfd for the new file
          descriptor (closing any old file associated with newfd).

     SOURCE
          /usr/local/plan9/src/lib9/dup.c

     DIAGNOSTICS
          Sets errstr.

     BUGS
          To avoid name conflicts with the underlying system, dup is a
          preprocessor macro defined as p9dup; see intro(3).

     Page 1                       Plan 9             (printed 11/4/25)