dup(2) [v7 man page]

DUP(2)								System Calls Manual							    DUP(2)

NAME

       dup, dup2 - duplicate an open file descriptor

SYNOPSIS

       dup(fildes)
       int fildes;

       dup2(fildes, fildes2)
       int fildes, fildes2;

DESCRIPTION

       Given  a  file  descriptor  returned from an open, pipe, or creat call, dup allocates another file descriptor synonymous with the original.
       The new file descriptor is returned.

       In the second form of the call, fildes is a file descriptor referring to an open file, and fildes2 is a non-negative integer less than  the
       maximum	value  allowed	for  file  descriptors	(approximately	19).  Dup2 causes fildes2 to refer to the same file as fildes.	If fildes2
       already referred to an open file, it is closed first.

SEE ALSO

       creat(2), open(2), close(2), pipe(2)

DIAGNOSTICS

       The value -1 is returned if: the given file descriptor is invalid; there are already too many open files.

ASSEMBLER

       (dup = 41.)
       (file descriptor in r0)
       (new file descriptor in r1)
       sys dup
       (file descriptor in r0)

       The dup2 entry is implemented by adding 0100 to fildes.

																	    DUP(2)

dup2(3C)						   Standard C Library Functions 						  dup2(3C)

NAME

       dup2 - duplicate an open file descriptor

SYNOPSIS

       #include <unistd.h>

       int dup2(int fildes, int fildes2);

DESCRIPTION

       The dup2() function causes the file descriptor fildes2 to refer to the same file as fildes. The fildes argument is a file descriptor refer-
       ring to an open file, and fildes2 is a non-negative integer less than the current value for the maximum number  of  open  file  descriptors
       allowed	the  calling  process.	 See  getrlimit(2).  If fildes2 already refers to an open file, not fildes, it is closed first. If fildes2
       refers to fildes, or if fildes is not a valid open file descriptor, fildes2 will not be closed first.

       The dup2() function is equivalent to  fcntl(fildes, F_DUP2FD, fildes2).

RETURN VALUES

       Upon successful completion a non-negative integer representing the file descriptor is returned. Otherwise, -1 is returned and errno is  set
       to indicate the error.

ERRORS

       The dup2() function will fail if:

       EBADF	       The fildes argument is not a valid open file descriptor.

       EBADF	       The files2 argument is negative or is not less than the current resource limit returned by getrlimit(RLIMIT_NOFILE, ...).

       EINTR	       A signal was caught during the dup2() call.

       EMFILE	       The process has too many open files.  See  fcntl(2).

ATTRIBUTES

       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Interface Stability	     |Standard			   |
       +-----------------------------+-----------------------------+
       |MT-Level		     |Async-Signal-Safe 	   |
       +-----------------------------+-----------------------------+

SEE ALSO

       close(2), creat(2), exec(2), fcntl(2), getrlimit(2), open(2), pipe(2), lockf(3C), attributes(5), standards(5)

SunOS 5.10							    19 Dec 2003 							  dup2(3C)