fd(4)                            UNIX System V                            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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