commit 536a3790646ac628c4109e9c6f3cadef114e9525
Author: Michael Clemens <clemens@fsfe.org>
Date:   Thu Apr 1 11:22:14 2021 +0200

    initial commit

diff --git a/monitor_backup_dir.sh b/monitor_backup_dir.sh
new file mode 100644
index 0000000..f6bfb4d
--- /dev/null
+++ b/monitor_backup_dir.sh
@@ -0,0 +1,21 @@
+target_dir=/var/borg
+hash_dir=/var/hashes
+mail_to="xxx@xxxx.xxx"
+
+find ${target_dir}/* -maxdepth 0 -type d  | while read line; do
+    host=$(echo "$line"  | awk -F" +|/" '{print $NF}')
+    if [[ ! $host =~ ^(lost\+found)$ ]]; then
+        hash=$(mtree -cxp "$line" | grep -E -- ^\[^\#] | sha256sum)
+        if test -f "${hash_dir}/$host"; then
+            difference=$(diff ${hash_dir}/$host <(echo "$hash"))
+            if [ "$difference" == "" ]; then
+                mail_body="The host ${host} was not backed up since the last check. Please forward this mail to the owner of the affected system."
+                echo "$mail_body" | mail -s "${host} not backed up!" "$mail_to"
+            fi
+        else
+            mail_body="No previously generated hash for the ${host} could be found - probably because it ran for the first time. Please forward this mail to the owner of the affected system."
+            echo "$mail_body" | mail -s "Error while checking ${host} for missed backups!" "$mail_to"
+        fi
+        echo "$hash" > "${hash_dir}/$host"
+    fi
+done