Function nc::fcntl

pub fn fcntl(fd: i32, cmd: i32, arg: usize) -> Result<i32, Errno>

manipulate file descriptor.

let path = "/etc/passwd";
let ret = nc::open(path, nc::O_RDONLY, 0);
assert!(ret.is_ok());
let fd = ret.unwrap();

let ret = nc::fcntl(fd, nc::F_DUPFD, 0);
assert!(ret.is_ok());
let fd2 = ret.unwrap();
assert!(nc::close(fd).is_ok());
assert!(nc::close(fd2).is_ok());