Improved KB about Snapper

knowledge base/snapper.md

@@ -3,29 +3,47 @@
 ## TL;DR
 
 ```sh
-# list existing configurations
+# List existing configurations.
 snapper list-config
 
-# list existing snapshots
+# List existing snapshots.
 snapper list
 
-# create a manual standalone snapshot
-snapper --config root create --type single --description "manual checkpoint" --userdata "important=yes" --read-only
+# Create a manual standalone snapshot.
+snapper \
+  --config root \
+  create --read-only \
+    --type single \
+    --description "manual checkpoint" \
+    --userdata "important=yes"
 
-# rollback to snapshot 0
+# Rollback to snapshot #0.
 snapper rollback 0
 
-# delete one or more snapshots
+# Delete one or more snapshots.
 snapper delete 5
 snapper delete --sync {7..9}
 
-# compare 2 snapshots
+# Compare 2 snapshots.
 snapper status 0..6
 snapper diff 6..21
+
+# Change values of an existing snapshot.
+# the cleanup algorithm must be one of 'number', 'timeline', 'empty-pre-post' or
+# '' (empty string, to cancel).
+# Any description must be less than 25 characters.
+# Any userdata must contain KEY=VALUE couples.
+snapper modify \
+  --userdata 'important=yes' \
+  --description 'new description' \
+  --cleanup-algorithm '' 12
 ```
 
 ## Further readings
 
+- [System recovery and snapshot management with Snapper]
 - [Arch Wiki]
 
+<!-- external references -->
 [arch wiki]: https://wiki.archlinux.org/title/snapper
+[system recovery and snapshot management with snapper]: https://doc.opensuse.org/documentation/leap/archive/15.0/reference/html/book.opensuse.reference/cha.snapper.html