Add SNAP_SYNC_EXCLUDE to exclude some configurations

Fixes #11.

README.md

@@ -46,6 +46,9 @@ place. Example:
 
 The timer included is weekly. Edit both files to your taste.
 
+You can exclude a configuration from backup by setting `SNAP_SYNC_EXCLUDE=yes`
+in your snapper configuration file.
+
 ## Example command line usage
 
 ### No arguments

bin/snap-sync

@@ -135,6 +135,8 @@ selected_configs=${selected_configs:-$SNAPPER_CONFIGS}
 # Initial configuration of where backup directories are
 for x in $selected_configs; do
 
+    SNAP_SYNC_EXCLUDE=no
+
     if [[ -f "/etc/snapper/configs/$x" ]]; then
         source /etc/snapper/configs/$x
     else
@@ -142,6 +144,10 @@ for x in $selected_configs; do
         exit 1
     fi
 
+    if [[ $SNAP_SYNC_EXCLUDE == "yes" ]]; then 
+        continue
+    fi
+
     old_num=$(snapper -c "$x" list -t single | awk '/'"$selected_uuid"'/ {print $1}')
     old_snap=$SUBVOLUME/.snapshots/$old_num/snapshot
 
@@ -166,7 +172,7 @@ done
 # Actual backing up
 for x in $selected_configs; do
 
-    printf "\n"
+    SNAP_SYNC_EXCLUDE=no
 
     if [[ -f "/etc/snapper/configs/$x" ]]; then
         source /etc/snapper/configs/$x
@@ -175,6 +181,12 @@ for x in $selected_configs; do
         exit 1
     fi
 
+    if [[ $SNAP_SYNC_EXCLUDE == "yes" ]]; then 
+        continue
+    fi
+
+    printf "\n"
+
     old_num=$(snapper -c "$x" list -t single | awk '/'"$selected_uuid"'/ {print $1}')
     old_snap=$SUBVOLUME/.snapshots/$old_num/snapshot