DUP2(S) UNIX System V DUP2(S)
Name
dup2 - duplicate an open file descriptor
Syntax
int dup2 (fildes, fildes2)
int fildes, fildes2;
Description
The fildes argument is a file descriptor referring to an
open file, and fildes2 is a non-negative integer less than
NOFiles. dup2 causes fildes2 to refer to the same file as
fildes. If fildes2 already referred to an open file, it is
closed first.
The dup2 function will fail if one or more of the following
is true:
[EBADF] fildes is not a valid open file descriptor.
[EMFILE] NOFiles file descriptors are currently open.
See Also
creat(S), close(S), exec(S), fcntl(S), open(S), pipe(S),
lockf(S).
Diagnostics
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.
Standards Conformance
dup2 is conformant with:
IEEE POSIX Std 1003.1-1988 with C Standard Language-
Dependent System Support;
and NIST FIPS 151-1.
(printed 6/20/89)