Moved main conditional out of previously existing function, added hard-coded command line to own function, added script options loop

zfs/zfs-selective-destroy.sh

@@ -1,14 +1,25 @@
 #!/bin/bash
 set -euo pipefail
 
-zfs-clean () {
-    if [ -z "$1" ]; then
-        exit 1
-    elif [ "$1" == "upgrades" ]; then
-        if [ -z "$2" ]; then
-            zfs list -t snapshot | grep 'apt-' | sed 's| .*$||g' | head -n -5 | xargs -d '\n' -I {} sudo zfs destroy {}
-        else
-            zfs list -t snapshot | grep "${2}" | sed 's| .*$||g' | head -n -5 | xargs -d '\n' -I {} sudo zfs destroy {}
-        fi
+clear-apt-snaps () {
+    zfs list -t snapshot | grep 'apt-' | sed 's| .*$||g' | head -n -5 | xargs -d '\n' -I {} sudo zfs destroy {}
+}
+
+if [ -z "$1" ]; then
+    exit 1
+fi
+    
+if ! [ -z "$1" ] && [ "$1" == "upgrades" ]; then
+    while getopts "r:" opt; do
+        case "$opt" in
+            r) REGEX=${OPTARG};;
+            *) exit 1;;
+        esac
+    done
+
+    if [ -z "$REGEX" ]; then
+        clear-apt-snaps
+    else
+        zfs list -t snapshot | grep "${REGEX}" | sed 's| .*$||g' | head -n -5 | xargs -d '\n' -I {} sudo zfs destroy {}
     fi
-}
+fi