FD(4FS) File Systems FD(4FS)

NAME

fd, stdin, stdout, stderr - 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(2), and mode is ignored.
As with dup(2), 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/stdin is a
synonym for /dev/fd/0, /dev/stdout for /dev/fd/1, and /dev/stderr for
/dev/fd/2.

DIAGNOSTICS

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

SEE ALSO

creat(2), dup(2), open(2)

illumos July 3, 1990 illumos