local/bin/btrfs-snap-all: Add preview option.

.local/bin/btrfs-snap-all

@@ -6,36 +6,59 @@ Usage: ${0##*/}
 
 Snapshot all Btrfs subvolumes older than 1 day to a read-only '.snapshots/SUBVOLUME/DATE'.
 
+Options:
+
+  -n: No preview.
+
 EOF
 }
 
-if [ $# -ne 0 ]; then
-	usage
-	exit 1
-fi
+OPT_PREVIEW=true
+while getopts ":hn" opt; do
+	case $opt in
+	h)
+		usage
+		exit ;;
+	n)
+		OPT_PREVIEW=false ;;
+	\?)
+		usage
+		exit 1 ;;
+	esac
+done
 
-while IFS= read -r fs; do
+shift $(($OPTIND - 1))
+
+snap () { # $1=fs $2=subvol
+	local fs=$1
+	local subvol=$2
+	local choice=N
+	local last=$(find "$fs/.snapshots/$subvol" -maxdepth 1 | tail -1)
+
+	$OPT_PREVIEW && rmirror "$fs/$subvol" "$last"
+
+	echo -n "==> Snapshot '$fs/${subvol}'? (y/N) "
+	read -r choice
+	echo ""
+	case "$choice" in
+	Y|y)
+		btrfs-snap "$fs/$subvol" ;;
+	esac
+}
+
+for fs in $(findmnt -t btrfs -n --output TARGET); do
 	for subvol in private public; do
-		last=$(ls -1 .snapshots/"$subvol" | tail -1 | sed 's/_/ /')
+		last=$(ls -1 "$fs"/.snapshots/"$subvol" | tail -1 | sed 's/_/ /')
 		if [ -z "$last" ]; then
 			continue
 		fi
 		last_date=$(date --date="$last" +%s)
 		now=$(date +%s)
 		if [ $(($now - $last_date)) -gt 86400 ]; then
-			choice=N
-			echo -n "==> Snapshot '$fs/${subvol}'? (y/N) "
-			read -r choice
-			case "$choice" in
-			Y|y)
-				btrfs-snap "$fs/$subvol" ;;
-			esac
-			unset choice
+			snap "$fs" "$subvol"
 		fi
 		unset now
 		unset last_date
 		unset last
 	done
-done <<EOF
-$(findmnt -t btrfs -n --output TARGET)
-EOF
+done