1FD(4)                      Kernel Interfaces Manual                      FD(4)
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NAME

6       fd, stdin, stdout, stderr file descriptor files
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DESCRIPTION

9       The  files  /dev/fd/0 through /dev/fd/# refer to file descriptors which
10       can be accessed through the file system.  If  the  file  descriptor  is
11       open and the mode the file is being opened with is a subset of the mode
12       of the existing descriptor, the call:
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14            fd = open("/dev/fd/0", mode);
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16       and the call:
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18            fd = fcntl(0, F_DUPFD, 0);
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20       are equivalent.
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22       Opening the files /dev/stdin, /dev/stdout and /dev/stderr is equivalent
23       to the following calls:
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25            fd = fcntl(STDIN_FILENO,  F_DUPFD, 0);
26            fd = fcntl(STDOUT_FILENO, F_DUPFD, 0);
27            fd = fcntl(STDERR_FILENO, F_DUPFD, 0);
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29       Flags  to the open(2) call other than O_RDONLY, O_WRONLY and O_RDWR are
30       ignored.
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FILES

33       /dev/fd/#
34       /dev/stdin
35       /dev/stdout
36       /dev/stderr
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SEE ALSO

39       tty(4)
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434th Berkeley Distribution      February 4, 1997                          FD(4)