tail head cat sleep
QR code linking to this page

Manual Pages  — FD

NAME

fd, stdin, stdout, stderr – file descriptor files

CONTENTS

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)

FD (4) June 9, 1993

tail head cat sleep
QR code linking to this page


Please direct any comments about this manual page service to Ben Bullock. Privacy policy.

Our grievance is not just against Unix itself, but against the cult of Unix zealots who defend and nurture it. They take the heat, disease, and pestilence as givens, and, as ancient shamans did, display their wounds, some self-inflicted, as proof of their power and wizardry. We aim, through bluntness and humor, to show them that they pray to a tin god, and that science, not religion, is the path to useful and friendly technology.
— The Unix Haters' handbook