| stderr, fd, stdin, stdout(4) | file descriptor files |
| fd, stderr, stdin, stdout(4) | file descriptor files |
| stdin, fd, stderr, stdout(4) | file descriptor files |
| stdout, fd, stderr, stdin(4) | file descriptor files |
| FD(4) | MidnightBSD Kernel Interfaces Manual | FD(4) |
fd, stdin,
stdout, stderr —
file descriptor files
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.
By default, /dev/fd is provided by devfs(5), which provides nodes for the first three file descriptors. Some sites may require nodes for additional file descriptors; these can be made available by mounting fdescfs(5) on /dev/fd.
| June 9, 1993 | midnightbsd-3.1 |