fd(4) BSD Kernel Interfaces Manual fd(4)
NAME
     fd, stdin, stdout, stderr -- file descriptor files
DESCRIPTION
     The files /dev/fd/0 through /dev/fd/# refer to file descriptors which can
     be accessed through the file system.  If the file descriptor is open and
     the mode the file is being opened with is a subset of the mode of the
     existing descriptor, the call:
           fd = open("/dev/fd/0", mode);
     and the call:
           fd = fcntl(0, F_DUPFD, 0);
     are equivalent.
     Opening the files /dev/stdin, /dev/stdout and /dev/stderr is equivalent
     to the following calls:
           fd = fcntl(STDIN_FILENO,  F_DUPFD, 0);
           fd = fcntl(STDOUT_FILENO, F_DUPFD, 0);
           fd = fcntl(STDERR_FILENO, F_DUPFD, 0);
     Flags to the open(2) call other than O_RDONLY, O_WRONLY and O_RDWR are
     ignored.
FILES
     /dev/fd/#
     /dev/stdin
     /dev/stdout
     /dev/stderr
SEE ALSO
     tty(4)
BSD                              June 9, 1993                              BSD
Mac OS X 10.9 - Generated Tue Oct 15 20:57:14 CDT 2013
