Manual browser: stdin(4)

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FD(4) Kernel Interfaces Manual FD(4)

NAME

fd, stdin, stdout, stderrfile 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), mount_fdesc(8)

NOTE

The floppy disk driver on some ports is also called fd; see fdc(4) for its documentation.
December 29, 2013 NetBSD 7.0