I can recognize automatic snapshots now.

.gitignore

@@ -0,0 +1 @@
+zfsbackup

main.go

@@ -9,7 +9,7 @@ import (
 
 const zfsRegexStart string = "zfs-auto-snap"
 const zfsRegexIncrement string = "(?P<increment>yearly|monthly|weekly|daily|hourly|frequent)"
-const zfsRegexDateStamp string = "(?P<month>[[:digit:]]{2})-(?P<day>[[:digit:]]{2})-(?P<hour>[[:digit:]]{2})(?P<minute>[[:digit:]]{2})"
+const zfsRegexDateStamp string = "(?P<year>[[:digit:]]{4})-(?P<month>[[:digit:]]{2})-(?P<day>[[:digit:]]{2})-(?P<hour>[[:digit:]]{2})(?P<minute>[[:digit:]]{2})"
 
 var zfsRegex = regexp.MustCompile(zfsRegexStart + "_" + zfsRegexIncrement + "-" + zfsRegexDateStamp)
 
@@ -21,9 +21,8 @@ func testSnapshot(possible string, increment string) (bool, bool) {
 	var isASnapshot = true
 	if matches[1] == increment {
 		return isASnapshot, true
-	} else {
-		return isASnapshot, false
 	}
+	return isASnapshot, false
 }
 
 func isAYearlySnapshot(possible string) bool {
@@ -56,26 +55,19 @@ func isAFrequentSnapshot(possible string) bool {
 	return isFrequent
 }
 
+const poolNameRegex string = "(?:[[:word:]-.]+)+(?:/?[[:word:]-.]+)*"
+
+var snapshotLineRegex = regexp.MustCompile("^" + poolNameRegex + "@" + zfsRegex.String() + ".*$")
+
 func main() {
+	//fmt.Println(snapshotLineRegex.MatchString("dpool/www@zfs-auto-snap_frequent-2020-08-04-1830\t0B\t-\t201M\t-"))
 	input := bufio.NewScanner(os.Stdin)
 	for input.Scan() {
-		if isAYearlySnapshot(input.Text()) {
-			fmt.Printf("%s\t%s\n", input.Text(), "Is a yearly snapshot.")
-		}
-		if isAMonthlySnapshot(input.Text()) {
-			fmt.Printf("%s\t%s\n", input.Text(), "Is a monthly snapshot.")
-		}
-		if isAWeeklySnapshot(input.Text()) {
-			fmt.Printf("%s\t%s\n", input.Text(), "Is a weekly snapshot.")
-		}
-		if isADailySnapshot(input.Text()) {
-			fmt.Printf("%s\t%s\n", input.Text(), "Is a daily snapshot.")
-		}
-		if isAnHourlySnapshot(input.Text()) {
-			fmt.Printf("%s\t%s\n", input.Text(), "Is an hourly snapshot.")
-		}
-		if isAFrequentSnapshot(input.Text()) {
-			fmt.Printf("%s\t%s\n", input.Text(), "Is a frequent snapshot.")
+		if snapshotLineRegex.MatchString(input.Text()) {
+			fmt.Println(snapshotLineRegex.FindStringSubmatch(input.Text()))
+			fmt.Println(snapshotLineRegex.SubexpNames())
+		} else {
+			fmt.Printf("%s\t%s\n", input.Text(), "Is not a snapshot.")
 		}
 	}
 	if err := input.Err(); err != nil {