catch SIGINT and SIGTERM and write them into a log file to investigate signal sending

catch_signals.rs

extern crate libc;

use libc::{c_int, SIGTERM, SIGINT, SIG_ERR, signal, pause};
use std::fs::OpenOptions;
use std::io::Write;

fn sig(sig:c_int) {
    let mut file = OpenOptions::new().append(true).open("/tmp/signals.txt").expect("cannot open");
    match sig {
        SIGINT => file.write_all(b"sigint\n"),
        SIGTERM => file.write_all(b"sigterm\n"),
        _ => file.write_all(b"other sit\n"),
    };
}

fn main() {
    unsafe {
        if signal(SIGINT, sig as usize) == SIG_ERR {
            println!("error registering sig_int");
        }
        if signal(SIGTERM, sig as usize) == SIG_ERR {
            println!("error registering sig_term");
        }
        pause();
    }
}