fd(4)                                                                 fd(4)


   NAME
         /dev/fd - file descriptor files

   DESCRIPTION
         These files, conventionally called /dev/fd/0, /dev/fd/1, /dev/fd/2,
         and so on, refer to files accessible through file descriptors.  If
         file descriptor n is open, these two system calls have the same
         effect:

               fd = open("/dev/fd/n",mode);
               fd = dup(n);

         On these files creat(2) is equivalent to open, and mode is ignored.
         As with dup, subsequent reads or writes on fd fail unless the
         original file descriptor allows the operations.

         For convenience in referring to standard input, standard output, and
         standard error, an additional set of names is provided: /dev/fd/0 is
         a synonym for /dev/fd/0, /dev/fd/1 for /dev/fd/1, and /dev/fd/2 for
         /dev/fd/2.

   SEE ALSO
         open(2), dup(2)

   DIAGNOSTICS
         open(2) returns -1 and EBADF if the associated file descriptor is not
         open.


























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