dup2 - duplicate an open file descriptor to a specific slot
int dup2(int fildes, int fildes2);
fildes is a file descriptor obtained from a creat(), open(), dup(),
fcntl(), or pipe() system call.
fildes2 is a non-negative integer less than the maximum value allowed
for file descriptors.
dup2() causes fildes2 to refer to the same file as fildes. If fildes2
refers to an already open file, the open file is closed first.
The file descriptor returned by dup2() has the following in common
+ Same open file (or pipe).
+ Same file pointer (that is, both file descriptors share one
+ Same access mode (read, write or read/write).
+ Same file status flags (see fcntl(2), F_DUPFD).
The new file descriptor is set to remain open across exec() system
calls. See fcntl(2).
This routine is found in the C library. Programs using dup2() but not
using other routines from the Berkeley importability library (such as
the routines described in bsdproc(3C)) should not give the -lBSD
option to ld(1).
Upon successful completion, dup2() returns the new file descriptor as
a non-negative integer, fildes2. Otherwise, it returns -1 and sets
errno to indicate the error.
dup2() fails if the following is true:
[EBADF] fildes is not a valid open file descriptor or fildes2
is not in the range of legal file descriptors.
[EINTR] An attempt to close fildes2 was interrupted by a
signal. The file is still open.
Hewlett-Packard Company - 1 - HP-UX Release 11i: November 2000
close(2), creat(2), dup(2), exec(2), fcntl(2), open(2), pipe(2).
dup2(): AES, SVID2, SVID3, XPG3, XPG4, FIPS 151-2, POSIX.1
Hewlett-Packard Company - 2 - HP-UX Release 11i: November 2000