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!!NAME dup2 - duplicate a file descriptor !!SYNOPSIS __#include <unistd.h>__ __int dup2(int__ ''oldfd''__, int__ ''newfd''__);__ !!DESCRIPTION __dup2__ creates a copy of the file descriptor ''oldfd''. After successful return of dup2(2), 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. dup2(2) makes ''newfd'' be the copy of ''oldfd'', closing ''newfd'' first if necessary. !!RETURN VALUE __dup2__ 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, or ''newfd'' is out of the allowed range for file descriptors. ;[EMFILE]: The process already has the maximum number of file descriptors open and tried to open a new one. !!WARNING The error returned by dup2(2) is different to that returned by __fcntl(__..., __F_DUPFD__, ...__)__ (fcntl(2)) when ''newfd'' is out of range. On some systems dup2(2) also sometimes returns [EINVAL] like __F_DUPFD__. !!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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dup2(2)
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fcntl(2)
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syscalls(2)
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