dup2(3C)                                                    dup2(3C)


       NAME
             dup2 - duplicate an open file descriptor

       SYNOPSIS
             #include <unistd.h>
             int dup2(int fildes, int fildes2);

       DESCRIPTION
             fildes is a file descriptor referring to an open file, and
             fildes2 is a non-negative integer less than the maximum number
             of open files available.  dup2 causes fildes2 to refer to the
             same file as fildes.  If fildes2 already referred 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.

          Return Values
             Upon successful completion a non-negative integer, namely, the
             file descriptor, is returned.  Otherwise, a value of -1 is
             returned and errno is set to indicate the error.

          Errors
             dup2 will fail if one or more of the following are true:

             EBADF          fildes is not a valid open file descriptor.

             EBADF          fildes2 is negative or greater than or equal to
                            the maximum number of open files available.

             EINTR          a signal was caught during the dup2 call.

             EMFILE         The maximum number of file descriptors are
                            currently open.

       REFERENCES
             close(2), creat(2), exec(2), fcntl(2), limits(4), lockf(3C),
             open(2), pipe(2)











                           Copyright 1994 Novell, Inc.               Page 1