View Source: dup(2) - Waikato Linux Users Group

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!!NAME

dup, dup2 - duplicate a file descriptor
!!SYNOPSIS


 __#include <unistd.h>__
 __int dup(int__ ''oldfd''__);__

!!DESCRIPTION

__dup__ create a copy of the file descriptor ''oldfd''.


After successful return of __dup__, the old and new descriptors may be used interchangeably. They share locks, file position pointers and flags; for example, if the file position is modified by using lseek(2) on one of the descriptors, the position is also changed for the other.

The two descriptors do __not__ share the close-on-exec flag, however.

dup(2) uses the lowest-numbered unused descriptor for the new descriptor.

!!RETURN VALUE

__dup__ returns the new descriptor, or -1 if an error occurred (in which case, ''errno'' is set appropriately).

!!ERRORS

;[EBADF]: ''oldfd'' isn't an open file descriptor
;[EMFILE]: The process already has the maximum number of file descriptors open and tried to open a new one.

!!CONFORMING TO

SVr4, SVID, POSIX, X/OPEN, BSD 4.3. SVr4 documents additional [EINTR] and [ENOLINK] error conditions. POSIX.1 adds [EINTR].

!!SEE ALSO

fcntl(2), open(2), close(2)

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Last edited on Thursday, October 31, 2002 5:53:01 pm by PerryLorier

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