Minor changes.

src/main.rs

@@ -3,9 +3,10 @@ extern crate ini;
 extern crate exitcode;
 
 use std::env;
+use std::path::Path;
+use std::process::Command;
 use std::thread;
 use std::time::Duration;
-use std::process::Command;
 
 /// Rule description structure
 pub struct Rule {
@@ -161,6 +162,13 @@ fn main() {
         "/etc/cai-watchdog.conf"
     };
 
+    if !Path::new(cfg_file).exists() {
+        println!("Error! Can't find configuration file.");
+        println!("Exiting...");
+
+        std::process::exit(exitcode::CONFIG);
+    }
+
     let cfg = ini!(cfg_file);
 
     let check_interval = cfg["main"]["check_interval"].clone().unwrap().parse::<u64>().unwrap() * 1000;