add btrbk to arch

arch.md

@@ -16,6 +16,7 @@
     - [Steam](#steam)
     - [XWayland](#xwayland)
     - [Wireguard](#wireguard)
+    - [btrbk](#btrbk)
   - [Help](#help)
     - [Update Grub](#update-grub)
     - [Downgrading Kernel](#downgrading-kernel)
@@ -134,8 +135,8 @@ Set up locale with correct information (required for certain binaries like minec
 1. `sudo pacman -S fprintd`
 2. `sudo systemctl enable --now fprintd`
 3. Enable fingerprint terminal login but prompt for password first (enter switches to prompt for fingerprint)
-   
-    sudo vim sudo vim /etc/pam.d/sudo and at the top of the file:
+
+    sudo vim /etc/pam.d/sudo and at the top of the file:
 
     ```conf
     # fingerprint auth
@@ -250,6 +251,67 @@ Provides compatibility with X server applications (like wine)
 
 1. `sudo pacman -S wireguard-tools`
 
+### btrbk
+
+1. Grab the btrbk binary from the github repo. Copy it to /usr/local/bin/btrbk.
+2. Create a snapshot config
+
+/etc/btrbk/snapshots.conf
+
+```conf
+snapshot_preserve_min   24h
+snapshot_preserve       14d
+
+volume /mnt/btr_pools/root
+    subvolume           root
+    snapshot_dir        .snapshots
+
+volume /mnt/btr_pools/root
+    subvolume           home
+    snapshot_dir        .snapshots
+
+volume /mnt/btr_pools/root
+    subvolume           libvirt
+    snapshot_dir        .snapshots
+
+volume /mnt/btr_pools/root
+    subvolume           nextcloud
+    snapshot_dir        .snapshots
+```
+
+3. Then create a snapshot service at /etc/systemd/system/btrbk_snapshots.service
+
+```conf
+[Unit]
+Description=Runs btrbk with config file at /etc/btrbk/snapshots.conf
+
+[Service]
+ExecStart=/usr/local/bin/btrbk -c /etc/btrbk/snapshots.conf -v run
+```
+
+4. Then create a timer for the service at /etc/systemd/system/btrbk_snapshots.timer
+
+```conf
+[Unit]
+Description=Run snapshots every hour
+
+[Timer]
+OnCalendar=hourly
+
+AccuracySec=10min
+Persistent=true
+Unit=btrbk_snapshots.service
+
+[Install]
+WantedBy=timers.target
+```
+
+5. Then enable the service
+
+```bash
+systemctl enable --now btrbk_snapshots.conf
+```
+
 ## Help
 
 ### Update Grub

pc_fedora.md

@@ -102,7 +102,7 @@ And timers to run the btrbk services on a regular schedule.
 Description=Run btrbk_snapshots every hour
 
 [Timer]
-OnCalendar=hourlyalways want to give it a device name; the implicit selection may be right in some cases but it's better not to rely on it.
+OnCalendar=hourly
 
 AccuracySec=10min
 Persistent=true