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FD(4) | Device Drivers 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.
IMPLEMENTATION NOTES¶
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.FILES¶
- /dev/fd/#
- /dev/stdin
- /dev/stdout
- /dev/stderr
SEE ALSO¶
tty(4), devfs(5), fdescfs(5)June 9, 1993 | Linux 4.9.0-9-amd64 |