From ffde698626c3f5516d0fdd68d1db021aea48010d Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?marc=20W=C3=A4ckerlin?= <marc@waeckerlin.org>
Date: Fri, 6 Oct 2017 16:50:54 +0200
Subject: [PATCH] added support for cron periods

---
 btrfs-snapshots.sh | 45 +++++++++++++++++++++++++++++++++++++++++----
 1 file changed, 41 insertions(+), 4 deletions(-)

diff --git a/btrfs-snapshots.sh b/btrfs-snapshots.sh
index 008dfaf..456c16d 100755
--- a/btrfs-snapshots.sh
+++ b/btrfs-snapshots.sh
@@ -6,6 +6,19 @@ TMP_MNT=${TMP_MNT:-/var/tmp/btrfs-backup}
 vols=()
 del=
 dryrun=0
+periodity=${a%/*}
+periodity=${periodity##*/}
+if [[ $periodity =~ ^cron\... ]]; then
+    periodity=${periodity#cron}
+else
+    periodity=
+fi
+case "$periodity" in
+    (.hourly) del=25;;
+    (.daily) del=8;;
+    (.weekly) del=5;;
+    (.monthly);;
+esac
 while test $# -gt 0; do
     case "$1" in
         (-h|--help) cat <<EOF
@@ -21,7 +34,7 @@ OPTIONS
 
 not yet implemented:
 
-  -d, --del <days>   delete snapshots older than given number of days
+  -d, --del <number> delete oldes snapshots beginning at <numbers>-th
 
 ENVIRONMENT
 
@@ -34,6 +47,19 @@ Creates a snapshot for all btrfs volumes specified. Snapshot is named
 from the subvol name or if there is no subvol, from the path by
 appending -snapshot-YYYY-MM-DD-HH-mm.
 
+To create regular snapshots on a daily base, just run:
+
+  sudo cp btrfs-snapshots.sh /etc/cron.daily/btrfs-snapshots
+
+If btrfs-snapshots is run from a cron.daily, cron.hourly,
+cron. monthly or cron.weekly directory, the periodity is automatically
+appended to the snapshot name, and the expiry is set meaningfull:
+
+  - hourly  → keep only 24 hours, --del 25
+  - daily   → keep only 7 days, --del 8
+  - weekly  → keep only 4 weeks, --del 5
+  - monthly → old snapshots are not deleted
+
 EOF
                     exit;;
         (-n|--dry-run) dryrun=1;;
@@ -72,19 +98,30 @@ for fs in ${BTRFS_VOLUMES}; do
             name=/${name//\//-}-
         fi
     fi
-    target="${name}snapshot-$(date +%Y-%m-%d-%H-%M)"
+    date="-$(date +%Y-%m-%d-%H-%M)"
+    target="${name}snapshot${periodity}"
     if test -n "$device"; then
         if test $dryrun -eq 1; then
             echo -e "→ \e[1mbackup ${subvol:+subvol $subvol of }$fs on $device\e[0m"
             echo " " mount "$device" "$TMP_MNT"
-            echo " " btrfs subvolume snapshot "${TMP_MNT}${subvol}" "${TMP_MNT}${target}"
+            echo " " btrfs subvolume snapshot "${TMP_MNT}${subvol}" "${TMP_MNT}${target}${date}"
+            if test -n "$del"; then
+                for f in $(ls -1 "${TMP_MNT}${target}${date}"-* | tail -n +"$del"); do
+                    echo " " btrfs subvolume delete "$f"
+                done
+            fi
             echo " " umount "$TMP_MNT"
         else
             if mount | grep -q " on $TMP_MNT type "; then
                 sudo umount "$TMP_MNT"
             fi
             sudo mount "$device" "$TMP_MNT"
-            sudo btrfs subvolume snapshot "${TMP_MNT}${subvol}" "${TMP_MNT}${target}"
+            sudo btrfs subvolume snapshot "${TMP_MNT}${subvol}" "${TMP_MNT}${target}${date}"
+            #if test -n "$del"; then
+            #    for f in $(ls -1 "${TMP_MNT}${target}${date}"-* | tail -n +"$del"); do
+            #        sudo btrfs subvolume delete "$f"
+            #    done
+            #fi
             sudo umount "$TMP_MNT"
         fi
     else