minor fixes; docs

README.md

@@ -5,7 +5,7 @@ A simple tool to notify you when your system memory usage is too high.
 Features:
 
 - uses `notify-send` to send notifications when memory usage reaches a certain threshold
-- major Linux distributions are supported
+- built for Linux (tested on Ubuntu 22.04 X11)
 - configurable threshold, check memory usage interval and resend notification delay
 
 Example desktop notification:
@@ -14,7 +14,7 @@ Example desktop notification:
 
 ## Usage
 
-Example usage that monitors memory usage by checking every 2 seconds, sends a notification when memory usage is above 80% and will not send another notification until after 10 seconds.
+Example usage that monitors memory usage by checking every 2 seconds, sends a notification when memory usage is above 80% and will not resend another notification until after 10 seconds.
 
 ```bash
 notifymem -threshold 80 -delay 10 -interval 2

monitor.go

@@ -45,8 +45,8 @@ func NewMonitor(notifier Notifier, opts MonitorOptions) (*Monitor, error) {
 		threshold:   opts.Threshold,
 	}
 
-	if m.interval < 100*time.Millisecond {
-		return nil, errors.New("interval must be at least 100ms")
+	if m.interval < 1*time.Second {
+		return nil, errors.New("interval must be at least 1s")
 	}
 
 	if m.notifier == nil {
@@ -57,8 +57,8 @@ func NewMonitor(notifier Notifier, opts MonitorOptions) (*Monitor, error) {
 		return nil, errors.New("resend delay must be at least 5s")
 	}
 
-	if m.threshold < 0 || m.threshold > 100 {
-		return nil, errors.New("threshold must be between 0 and 100")
+	if m.threshold < 1 || m.threshold > 100 {
+		return nil, errors.New("threshold must be between 1 and 100")
 	}
 
 	return m, nil
@@ -157,6 +157,9 @@ func memoryUsage(m memory) (int, error) {
 	if m.total == 0 {
 		return 0, errors.New("total memory is 0")
 	}
+	if m.avail == 0 {
+		return 0, errors.New("available memory is 0")
+	}
 
 	return int((float64(m.total-m.avail) / float64(m.total)) * 100), nil
 }