dup(2)									dup(2)

NAME    [Toc]    [Back]

     dup - duplicate an	open file descriptor

SYNOPSIS    [Toc]    [Back]

     #include <unistd.h>

     int dup(int fildes);

DESCRIPTION    [Toc]    [Back]

     fildes is a file descriptor obtained from a creat,	open, dup, fcntl,
     pipe, or ioctl system call.  dup returns a	new file descriptor having the
     following in common with the original:

	  Same open file (or pipe).

	  Same file pointer (i.e., both	file descriptors share one file
	  pointer).

	  Same access mode (read, write	or read/write).

     The new file descriptor is	set to remain open across exec system calls
     [see fcntl(2)].

     The file descriptor returned is the lowest	one available.

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

     EBADF	    fildes is not a valid open file descriptor.

     EINTR	    A signal was caught	during the dup system call.

     EMFILE	    The	process	has too	many open files	[see getrlimit(2)].

     ENOLINK	    fildes is on a remote machine and the link to that machine
		    is no longer active.

SEE ALSO    [Toc]    [Back]

     close(2), creat(2), exec(2), fcntl(2), getrlimit(2), open(2), pipe(2),
     dup2(3C), lockf(3C).

DIAGNOSTICS    [Toc]    [Back]

     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.


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