Update error message if command could not be found

src/exec/command.rs

@@ -32,7 +32,13 @@ pub fn execute_command(mut cmd: Command, out_perm: Arc<Mutex<()>>) {
             let _ = stdout.lock().write_all(&output.stdout);
             let _ = stderr.lock().write_all(&output.stderr);
         }
-        Err(why) => eprintln!("fd: exec error: {}", why),
+        Err(why) => {
+            if why.kind() == io::ErrorKind::NotFound {
+                eprintln!("fd: execution error: command not found");
+            } else {
+                eprintln!("fd: execution error: {}", why);
+            }
+        }
     }
 }
 
@@ -93,6 +99,12 @@ pub fn execute_command(mut cmd: Command, out_perm: Arc<Mutex<()>>) {
             let _ = io::copy(&mut pout, &mut stdout.lock());
             let _ = io::copy(&mut perr, &mut stderr.lock());
         }
-        Err(why) => eprintln!("fd: exec error: {}", why),
+        Err(why) => {
+            if why.kind() == io::ErrorKind::NotFound {
+                eprintln!("fd: execution error: command not found");
+            } else {
+                eprintln!("fd: execution error: {}", why);
+            }
+        }
     }
 }