Function nix::unistd::close  
pub fn close(fd: RawFd) -> Result<()>Documentation
Close a raw file descriptor
Be aware that many Rust types implicitly close-on-drop, including
std::fs::File.  Explicitly closing them with this method too can result in
a double-close condition, which can cause confusing EBADF errors in
seemingly unrelated code.  Caveat programmer.  See also
close(2).
Examples
use std::os::unix::io::AsRawFd;
use nix::unistd::close;
let f = tempfile::tempfile().unwrap();
close(f.as_raw_fd()).unwrap();   // Bad!  f will also close on drop!use std::os::unix::io::IntoRawFd;
use nix::unistd::close;
let f = tempfile::tempfile().unwrap();
close(f.into_raw_fd()).unwrap(); // Good.  into_raw_fd consumes f