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Standard C Library Functionsdup2(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 referring 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 TYPEATTRIBUTE VALUE
MT-LevelSafe

SEE ALSO

 

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


SunOS 5.9Go To TopLast Changed 18 Apr 1997

 
      
      
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