1 files changed, 45 insertions, 0 deletions

diff --git a/snap.sh b/snap.sh
new file mode 100755
index 0000000..36f32e6
--- /dev/null
+++ b/snap.sh
@@ -0,0 +1,45 @@
+#!/bin/sh -euf
+
+MOUNT_DIRECTORY="/var/backups/dataset-snapshots"
+SNAPSHOT_LABEL="snap"
+
+usage() (
+        echo "snap.sh <snap|free> <dataset>"
+        echo
+        echo "Creates or destroys a snapshot of a ZFS dataset, labelled with @$SNAPSHOT_LABEL."
+        echo "Snapshots are automatically mounted in $MOUNT_DIRECTORY."
+        echo "If a snapshot already exists, it is replaced."
+        echo
+)
+
+create_snapshot() (
+        DATASET="$1"
+
+        SNAPSHOT_NAME="$DATASET@$SNAPSHOT_LABEL"
+        SNAPSHOT_DIRECTORY="$MOUNT_DIRECTORY/$DATASET"
+
+        if zfs list "$SNAPSHOT_NAME" >/dev/null 2>/dev/null; then
+                echo "Snapshot already exists. Overwriting."
+                destroy_snapshot "$DATASET"
+        fi
+
+        zfs snapshot "$SNAPSHOT_NAME"
+        mkdir -p "$SNAPSHOT_DIRECTORY"
+        mount -t zfs "$SNAPSHOT_NAME" "$SNAPSHOT_DIRECTORY"
+)
+
+destroy_snapshot() (
+        DATASET="$1"
+
+        SNAPSHOT_NAME="$DATASET@$SNAPSHOT_LABEL"
+
+        umount "$SNAPSHOT_NAME" 2>/dev/null || true
+        zfs destroy "$SNAPSHOT_NAME"
+)
+
+case "${1:-help}" in
+        "help") usage;;
+        "snap") create_snapshot "$2";;
+        "free") destroy_snapshot "$2";;
+esac
+