Fix bug Create entries with matching version (#170)

* Fix #169 
  * Create entries with matching version doesn't work properly:
  Adds missing "else continue;"

10-update_grub.conf

@@ -1,2 +0,0 @@
-[Service]
-ExecStartPost=/usr/sbin/grub-mkconfig -o /boot/grub/grub.cfg

Makefile

@@ -0,0 +1,71 @@
+PKGNAME ?= grub-btrfs
+PREFIX ?= /usr
+
+INITCPIO ?= false
+
+SHARE_DIR = $(DESTDIR)$(PREFIX)/share
+LIB_DIR = $(DESTDIR)$(PREFIX)/lib
+
+.PHONY: install uninstall help
+
+install:
+	@if test "$(shell id -u)" != 0; then \
+		echo "You are not root, run this target as root please."; \
+		exit 1; \
+	fi
+	@install -Dm755 -t "$(DESTDIR)/etc/grub.d/" 41_snapshots-btrfs
+	@install -Dm644 -t "$(DESTDIR)/etc/default/grub-btrfs/" config
+	@install -Dm644 -t "$(LIB_DIR)/systemd/system/" grub-btrfs.service
+	@install -Dm644 -t "$(LIB_DIR)/systemd/system/" grub-btrfs.path
+	@install -Dm644 -t "$(SHARE_DIR)/licenses/$(PKGNAME)/" LICENSE
+	@# Arch Linux like distros only :
+	@if test "$(INITCPIO)" = true; then \
+		install -Dm644 "initramfs/Arch Linux/overlay_snap_ro-install" "$(LIB_DIR)/initcpio/install/grub-btrfs-overlayfs"; \
+		install -Dm644 "initramfs/Arch Linux/overlay_snap_ro-hook" "$(LIB_DIR)/initcpio/hooks/grub-btrfs-overlayfs"; \
+	 fi
+	@install -Dm644 -t "$(SHARE_DIR)/doc/$(PKGNAME)/" README.md
+	@install -Dm644 "initramfs/readme.md" "$(SHARE_DIR)/doc/$(PKGNAME)/initramfs-overlayfs.md"
+
+uninstall:
+	@if test "$(shell id -u)" != 0; then \
+		echo "You are not root, run this target as root please."; \
+		exit 1; \
+	fi
+	@grub_dirname="$$(grep -oP '^[[:space:]]*GRUB_BTRFS_GRUB_DIRNAME=\K.*' "$(DESTDIR)/etc/default/grub-btrfs/config" | sed "s|\s*#.*||;s|(\s*\(.\+\)\s*)|\1|;s|['\"]||g")"; \
+	 rm -f "$${grub_dirname:-/boot/grub}/grub-btrfs.cfg"
+	@rm -f "$(DESTDIR)/etc/default/grub-btrfs/config"
+	@rm -f "$(DESTDIR)/etc/grub.d/41_snapshots-btrfs"
+	@rm -f "$(LIB_DIR)/systemd/system/grub-btrfs.service"
+	@rm -f "$(LIB_DIR)/systemd/system/grub-btrfs.path"
+	@rm -f "$(LIB_DIR)/initcpio/install/grub-btrfs-overlayfs"
+	@rm -f "$(LIB_DIR)/initcpio/hooks/grub-btrfs-overlayfs"
+	@# Arch Linux UNlike distros only :
+	@if test "$(INITCPIO)" != true && test -d "$(LIB_DIR)/initcpio"; then \
+		rmdir --ignore-fail-on-non-empty "$(LIB_DIR)/initcpio/install" || :; \
+		rmdir --ignore-fail-on-non-empty "$(LIB_DIR)/initcpio/hooks" || :; \
+		rmdir --ignore-fail-on-non-empty "$(LIB_DIR)/initcpio" || :; \
+	 fi
+	@rm -f "$(SHARE_DIR)/doc/$(PKGNAME)/README.md"
+	@rm -f "$(SHARE_DIR)/doc/$(PKGNAME)/initramfs-overlayfs.md"
+	@rm -f "$(SHARE_DIR)/licenses/$(PKGNAME)/LICENSE"
+	@rmdir --ignore-fail-on-non-empty "$(SHARE_DIR)/doc/$(PKGNAME)/" || :
+	@rmdir --ignore-fail-on-non-empty "$(SHARE_DIR)/licenses/$(PKGNAME)/" || :
+	@rmdir --ignore-fail-on-non-empty "$(DESTDIR)/etc/default/grub-btrfs" || :
+
+help:
+	@echo
+	@echo "Usage: $(MAKE) [ <parameter>=<value> ... ] [ <action> ]"
+	@echo
+	@echo "  actions: install"
+	@echo "           uninstall"
+	@echo "           help"
+	@echo
+	@echo "  parameter | type | description                    | defaults"
+	@echo "  ----------+------+--------------------------------+----------------------------"
+	@echo "  DESTDIR   | path | install destination            | <unset>"
+	@echo "  PREFIX    | path | system tree prefix             | '/usr'"
+	@echo "  SHARE_DIR | path | shared data location           | '\$$(DESTDIR)\$$(PREFIX)/share'"
+	@echo "  LIB_DIR   | path | system libraries location      | '\$$(DESTDIR)\$$(PREFIX)/lib'"
+	@echo "  PKGNAME   | name | name of the ditributed package | 'grub-btrfs'"
+	@echo "  INITCPIO  | bool | include mkinitcpio hook        | false"
+	@echo

README.md

@@ -1,119 +1,105 @@
-[![GitHub release](https://img.shields.io/github/release/Antynea/grub-btrfs.svg)](https://github.com/Antynea/grub-btrfs)
-  
+[![GitHub release](https://img.shields.io/github/release/Antynea/grub-btrfs.svg)](https://github.com/Antynea/grub-btrfs/releases)
+![](https://img.shields.io/github/license/Antynea/grub-btrfs.svg)
+
 ## grub-btrfs
 
-This is a version 3.xx of grub-btrfs
-##### BTC donation address: 1Lbvz244WA8xbpHek9W2Y12cakM6rDe5Rt
+This is a version 4.xx of grub-btrfs
+##### BTC donation address: `1Lbvz244WA8xbpHek9W2Y12cakM6rDe5Rt`
 ##
-### Description
+### Description :
+Improves Grub by adding "btrfs snapshots" to the Grub menu.
+
+You can boot your system on a "snapshot" from the Grub menu.  
+Supports manual snapshots, snapper, timeshift ...
+
+##### Warning: booting on read-only snapshots can be tricky
+
+If you choose to do it, `/var/log` or even `/var` must be on a separate subvolume.  
+Otherwise, make sure your snapshots are writeable.  
+See [this ticket](https://github.com/Antynea/grub-btrfs/issues/92) for more info.
+
+This project includes its own solution.  
+Refer to the [documentation](https://github.com/Antynea/grub-btrfs/blob/master/initramfs/readme.md).
 
-grub-btrfs, Include btrfs snapshots at boot options. (grub menu)
 ##
-### What does grub-btrfs v3.xx do :
-
-Simple rollback using snapshots you made previously.
-
+### What does grub-btrfs v4.xx do :
 * Automatically List snapshots existing on root partition (btrfs).
-
 * Automatically Detect if "/boot" is in separate partition.
-
-* Automatically Detect kernel, initramfs and intel microcode in "/boot" directory on snapshots.
-
-* Automatically Create corresponding "menuentry" in grub.cfg , which ensures a very easy rollback.
-
+* Automatically Detect kernel, initramfs and intel/amd microcode in "/boot" directory on snapshots.
+* Automatically Create corresponding "menuentry" in `grub.cfg`
 * Automatically detect snapper and use snapper's snapshot description if available.
+* Automatically generate `grub.cfg` if you use the provided systemd service.
+
 ##
-### How to customize it:
+### Installation :
+#### Arch Linux
+The package is available in the community repository [grub-btrfs](https://archlinux.org/packages/community/any/grub-btrfs/)
+```
+pacman -S grub-btrfs
+```
 
-You have the possibility to modify many parameters.
-Add this lines to /etc/default/grub:
+#### Manual
 
-* GRUB_BTRFS_SUBMENUNAME="Arch Linux Snapshots"
+* Run `make install` or look into Makefile for instructions on where to put each file.
+* Dependencies:
+  * [btrfs-progs](https://archlinux.org/packages/core/x86_64/btrfs-progs/)
+  * [grub](https://archlinux.org/packages/core/x86_64/grub/)
 
-	(Name menu appearing in grub.)
+NOTE: Generate your Grub menu after installation for the changes to take effect.  
+On Arch Linux use `grub-mkconfig -o /boot/grub/grub.cfg`.  
+On Debian-like distribution `update-grub` is an alias to `grub-mkconfig ...`
+##
+### Customization :
 
-* GRUB_BTRFS_PREFIXENTRY="Snapshot:"
+You have the possibility to modify many parameters in `/etc/default/grub-btrfs/config`.  
+See [config file](https://github.com/Antynea/grub-btrfs/blob/master/config) for more information.
 
-	(Add a name ahead your snapshots entries.)
-	
-* GRUB_BTRFS_DISPLAY_PATH_SNAPSHOT="true"
-	
-	(Show full path snapshot or only name, weird reaction with snapper)
-	
-* GRUB_BTRFS_TITLE_FORMAT="p/d/n"
-
- 	(Custom title, shows/hides p"prefix" d"date" n"name" in grub-menu, separator "/", custom order available)
-
-* GRUB_BTRFS_NKERNEL=("kernel-custom")
-
-	(Use it only if you have a custom kernel name)
-
-* GRUB_BTRFS_NINIT=("initramfs-custom.img" "initrd.img-custom")
-
-	(Use it only if you have a custom initramfs name)
-
-* GRUB_BTRFS_INTEL_UCODE=("intel-ucode.img")
-
-	(Use it only if you have custom intel-ucode)
-
-* GRUB_BTRFS_LIMIT="50"
-
-	(Limit the number of snapshots populated in the GRUB menu.)
-
-* GRUB_BTRFS_SUBVOLUME_SORT="descending"
-
-	(Sort the found subvolumes by newest first ("descending") or oldest first ("ascending"). 
-	If "ascending" is chosen then the $GRUB_BTRFS_LIMIT oldest
-	subvolumes will populate the menu.)
-
-* GRUB_BTRFS_SHOW_SNAPSHOTS_FOUND="true"
-	
-	(Show snapshots found during run "grub-mkconfig") 
-	
-* GRUB_BTRFS_SHOW_TOTAL_SNAPSHOTS_FOUND="true"
-	
-	(Show Total number of snapshots found during run "grub-mkconfig")
-
-* GRUB_BTRFS_IGNORE_SPECIFIC_PATH=("var/lib/docker")
-
-	(Ignore specific path during run "grub-mkconfig")
-
-* GRUB_BTRFS_SNAPPER_CONFIG="root"													
-
-	(Snapper's config name to use)
-
-* GRUB_BTRFS_DISABLE="true"
-
-	(Disable grub-btrfs)
-
-
-Generate grub.cfg (on Arch linux use grub-mkconfig -o /boot/grub/grub.cfg )
-
-grub-btrfs automatically generates snapshots entries.
-
-You will see it appear differents entries (e.g : Snapshot: 2018-01-03 15:08:41  @test1 )
 ##
 ### Automatically update grub
+1- If you would like grub-btrfs menu to automatically update when a snapshot is created or deleted:
+* Use `systemctl enable grub-btrfs.path`.
+  * `grub-btrfs.path` automatically (re)generates `grub-btrfs.cfg` when a modification appears in `/.snapshots` mount point (by default).
+  * If the `/.snapshots` mount point is already mounted, then use `systemctl start grub-btrfs.path` to start monitoring.  
+    Otherwise, the unit will automatically start monitoring when the mount point will be available.
+* If your snapshots location aren't mounted in `/.snapshots`, you must modify `grub-btrfs.path` unit using  
+`systemctl edit --full grub-btrfs.path` and run `systemctl reenable grub-btrfs.path` for changes take effect.  
+To find out the name of the `.mount` unit  
+use `systemctl list-units -t mount`.  
+	* For example: Timeshift mounts its snapshot folder in `/run/timeshift/backup/timeshift-btrfs/snapshots`.
 
-If you would like grub to automatically update when Snapper timeline snapshots and cleanups occur, simply install `10-update_grub.conf` in the following locations:
+		Use `systemctl edit --full grub-btrfs.path`.
+		Then replace the whole block by:
+		```
+		[Unit]
+		Description=Monitors for new snapshots
+		DefaultDependencies=no
+		Requires=run-timeshift-backup.mount
+		After=run-timeshift-backup.mount
+		BindsTo=run-timeshift-backup.mount
 
-- `/etc/systemd/system/snapper-timeline.service.d/`
-- `/etc/systemd/system/snapper-cleanup.service.d/`
+		[Path]
+		PathModified=/run/timeshift/backup/timeshift-btrfs/snapshots
 
-Once the configuration files are in place, `systemctl daemon-reload` should be run to reload the units and make the changes active.
+		[Install]
+		WantedBy=run-timeshift-backup.mount
+		```
+		Then save and finally run `systemctl reenable grub-btrfs.path` for changes take effect.  
+		Optional:  
+		If the `/run/timeshift/backup/timeshift-btrfs/snapshots` mount point is already mounted,  
+		then use `systemctl start grub-btrfs.path` to start monitoring.  
+		Otherwise, the unit will automatically start monitoring when the mount point will be available.  
+	* You can view your change to `systemctl cat grub-btrfs.path`.
+	* To revert change use `systemctl revert grub-btrfs.path`.
 
-##
-### Discussion
-Pour les francophones : https://forums.archlinux.fr/viewtopic.php?f=18&t=17177
+2- If you would like grub-btrfs menu to automatically update on system restart/shutdown:  
+[Look at this comment](https://github.com/Antynea/grub-btrfs/issues/138#issuecomment-766918328)  
+Currently not implemented  
+##### Warning :
+by default, `grub-mkconfig` command is used.  
+Might be `grub2-mkconfig` on some systems (Fedora ...).   
+Edit `GRUB_BTRFS_MKCONFIG` variable in `/etc/default/grub-btrfs/config` file to reflect this.
 ##
 ### Special thanks for assistance and contributions
-
 * [maximbaz](https://github.com/maximbaz)
-* [crossroads1112](https://github.com/crossroads1112)
-* [penetal](https://github.com/penetal)
-* [wesbarnett](https://github.com/wesbarnett)
-* [Psykar](https://github.com/Psykar)
-* [anyc](https://github.com/anyc)
-* [daftaupe](https://github.com/daftaupe)
-* [N-Parsons](https://github.com/N-Parsons)
+* [All contributors](https://github.com/Antynea/grub-btrfs/graphs/contributors)
 ##

config

@@ -0,0 +1,131 @@
+#!/usr/bin/env bash
+
+# Disable grub-btrfs.
+# Default: "false"
+#GRUB_BTRFS_DISABLE="true"
+
+# Name appearing in the Grub menu.
+# Default: "Use distribution information from /etc/os-release."
+#GRUB_BTRFS_SUBMENUNAME="Arch Linux snapshots"
+
+# Add a name ahead your snapshots entries in the Grub menu.
+# Default: "Snapshot:"
+#GRUB_BTRFS_PREFIXENTRY="Snapshot:"
+
+# Show full path snapshot or only name in the Grub menu, weird reaction with snapper.
+# Default: "true"
+#GRUB_BTRFS_DISPLAY_PATH_SNAPSHOT="false"
+
+# Custom title.
+# shows/hides p"prefix" d"date" n"name" in the Grub menu, separator "/", custom order available.
+# Default: "p/d/n"
+#GRUB_BTRFS_TITLE_FORMAT="p/d/n"
+
+# Limit the number of snapshots populated in the GRUB menu.
+# Default: "50"
+#GRUB_BTRFS_LIMIT="50"
+
+# Sort the found subvolumes by "ogeneration" or "generation" or "path" or "rootid".
+# # See Sorting section to https://btrfs.wiki.kernel.org/index.php/Manpage/btrfs-subvolume#SUBCOMMAND
+# "-rootid" means list snapshot by new ones first.
+# Default: "-rootid"
+#GRUB_BTRFS_SUBVOLUME_SORT="+ogen,-gen,path,rootid"
+
+# Show snapshots found during run "grub-mkconfig"
+# Default: "true"
+#GRUB_BTRFS_SHOW_SNAPSHOTS_FOUND="false"
+
+# Show Total of snapshots found during run "grub-mkconfig"
+# Default: "true"
+#GRUB_BTRFS_SHOW_TOTAL_SNAPSHOTS_FOUND="true"
+
+# By default, "grub-btrfs" automatically detects most existing kernels.
+# If you have one or more custom kernels, you can add them here.
+# Default: ("")
+#GRUB_BTRFS_NKERNEL=("kernel-custom" "vmlinux-custom")
+
+# By default, "grub-btrfs" automatically detects most existing initramfs.
+# If you have one or more custom initramfs, you can add them here.
+# Default: ("")
+#GRUB_BTRFS_NINIT=("initramfs-custom.img" "initrd-custom.img" "otherinit-custom.gz")
+
+# By default, "grub-btrfs" automatically detects most existing microcodes.
+# If you have one or more custom microcodes, you can add them here.
+# Default: ("")
+#GRUB_BTRFS_CUSTOM_MICROCODE=("custom-ucode.img" "custom-uc.img "custom_ucode.cpio")
+
+# Comma seperated mount options to be used when booting a snapshot.
+# They can be defined here as well as in the "/" line inside the respective snapshots'
+# "/etc/fstab" files.  Mount options found in both places are combined, and this variable
+# takes priority over `fstab` entries.
+# NB: Do NOT include "subvol=..." or "subvolid=..." here.
+# Default: ""
+#GRUB_BTRFS_ROOTFLAGS="space_cache,commit=10,norecovery"
+
+# Ignore specific path during run "grub-mkconfig".
+# Only exact paths are ignored.
+# e.g : if `specific path` = @, only `@` snapshot will be ignored.
+# Default: ("@")
+GRUB_BTRFS_IGNORE_SPECIFIC_PATH=("@")
+
+# Ignore prefix path during run "grub-mkconfig".
+# Any path starting with the specified string will be ignored.
+# e.g : if `prefix path` = @, all snapshots beginning with "@/..." will be ignored.
+# Default: ("var/lib/docker" "@var/lib/docker" "@/var/lib/docker")
+GRUB_BTRFS_IGNORE_PREFIX_PATH=("var/lib/docker" "@var/lib/docker" "@/var/lib/docker")
+
+# Ignore specific type of snapper's snapshot during run "grub-mkconfig".
+# Type = single, pre, post.
+# Default: ("")
+GRUB_BTRFS_IGNORE_SNAPPER_TYPE=("")
+
+# Ignore specific description of snapper's snapshot during run "grub-mkconfig".
+# Default: ("")
+GRUB_BTRFS_IGNORE_SNAPPER_DESCRIPTION=("")
+
+# By default "grub-btrfs" automatically detects your boot partition,
+# either located at the system root or on a separate partition,
+# but cannot detect if it is in a subvolume.
+# Change to "true" if you have a boot partition in a different subvolume.
+# Default: "false"
+#GRUB_BTRFS_OVERRIDE_BOOT_PARTITION_DETECTION="true"
+
+# Location of the folder containing the "grub.cfg" file.
+# Use by grub-btrfs to save the file "grub-btrfs.cfg".
+# Might be grub2 on some systems.
+# For example, on Fedora with EFI : "/boot/efi/EFI/fedora"
+# Default: "/boot/grub"
+#GRUB_BTRFS_GRUB_DIRNAME="/boot/grub2"
+
+# Location of kernels/initramfs/microcode.
+# Use by "grub-btrfs" to detect the boot partition and the location of kernels/initrafms/microcodes.
+# Default: "/boot"
+#GRUB_BTRFS_BOOT_DIRNAME="/boot"
+
+# Name/path of grub-mkconfig command, use by "grub-btrfs.service"
+# Might be 'grub2-mkconfig' on some systems (Fedora ...)
+# Default paths are /sbin:/bin:/usr/sbin:/usr/bin,
+# if your path is missing, report it on the upstream project.
+# For example, on Fedora : "/sbin/grub2-mkconfig"
+# You can use only name or full path.
+# Default: grub-mkconfig
+#GRUB_BTRFS_MKCONFIG=/usr/bin/grub2-mkconfig
+
+# Snapper
+# Snapper's config name to use
+# Default: "root"
+#GRUB_BTRFS_SNAPPER_CONFIG="root"
+
+# Password protection management for submenu,snapshots
+# Refer to the Grub documentation https://www.gnu.org/software/grub/manual/grub/grub.html#Authentication-and-authorisation
+# and this comment https://github.com/Antynea/grub-btrfs/issues/95#issuecomment-682295660
+#
+# Add authorized usernames separate by comma (foo,bar)
+# When Grub's password protection is enabled, the superuser is authorized by default, it isn't necessary to add it
+# Default: ""
+#GRUB_BTRFS_PROTECTION_AUTHORIZED_USERS="foo,bar"
+#
+# Disable authentication support for submenu of Grub-btrfs only (--unrestricted)
+# doesn't work if GRUB_BTRFS_PROTECTION_AUTHORIZED_USERS isn't empty
+# Default: "false"
+#GRUB_BTRFS_DISABLE_PROTECTION_SUBMENU="true"

grub-btrfs.path

@@ -0,0 +1,12 @@
+[Unit]
+Description=Monitors for new snapshots
+DefaultDependencies=no
+Requires=\x2esnapshots.mount
+After=\x2esnapshots.mount
+BindsTo=\x2esnapshots.mount
+
+[Path]
+PathModified=/.snapshots
+
+[Install]
+WantedBy=\x2esnapshots.mount

grub-btrfs.service

@@ -0,0 +1,11 @@
+[Unit]
+Description=Regenerate grub-btrfs.cfg
+
+[Service]
+Type=oneshot
+# Set the possible paths for `grub-mkconfig`
+Environment="PATH=/sbin:/bin:/usr/sbin:/usr/bin"
+# Load environment variables from the configuration
+EnvironmentFile=/etc/default/grub-btrfs/config
+# Regenerate just '/boot/grub/grub-btrfs.cfg' if it exists and is not empty, else regenerate the whole grub menu
+ExecStart=bash -c 'if [ -s "${GRUB_BTRFS_GRUB_DIRNAME:-/boot/grub}/grub-btrfs.cfg" ]; then /etc/grub.d/41_snapshots-btrfs; else ${GRUB_BTRFS_MKCONFIG:-grub-mkconfig} -o ${GRUB_BTRFS_GRUB_DIRNAME:-/boot/grub}/grub.cfg; fi' 

initramfs/Arch Linux/overlay_snap_ro-hook

@@ -0,0 +1,15 @@
+#!/usr/bin/ash
+
+run_latehook() {
+	local root_mnt="/new_root"
+	local current_dev=$(resolve_device "$root"); # resolve devices for blkid
+	if [[ $(blkid "${current_dev}" -s TYPE -o value) = "btrfs" ]] && [[ $(btrfs property get ${root_mnt} ro) != "ro=false" ]]; then # run only on a read only snapshot
+		local lower_dir=$(mktemp -d -p /)
+		local ram_dir=$(mktemp -d -p /)
+		mount --move ${root_mnt} ${lower_dir} # move new_root to lower_dir
+		mount -t tmpfs cowspace ${ram_dir}  #meuh!!! space, you can't test !
+		mkdir -p ${ram_dir}/upper
+		mkdir -p ${ram_dir}/work
+		mount -t overlay -o lowerdir=${lower_dir},upperdir=${ram_dir}/upper,workdir=${ram_dir}/work rootfs ${root_mnt}
+	fi
+}

initramfs/Arch Linux/overlay_snap_ro-install

@@ -0,0 +1,18 @@
+#!/bin/bash
+
+build() {
+    add_module btrfs
+    add_module overlay
+    add_binary btrfs
+    add_binary btrfsck
+    add_binary blkid
+    add_runscript
+}
+
+help() {
+    cat <<HELPEOF
+This hook uses overlayfs to boot on a read only snapshot.
+HELPEOF
+}
+
+# vim: set ft=sh ts=4 sw=4 et:

initramfs/readme.md

@@ -0,0 +1,45 @@
+### Description :
+
+Booting on a snapshot in read-only mode can be tricky.  
+An elegant way is to boot this snapshot using overlayfs (included in the kernel ≥ 3.18).
+
+Using overlayfs, the booted snapshot will behave like a live-cd in non-persistent mode.  
+The snapshot will not be modified, the system will be able to boot correctly, because a writeable folder will be included in the ram.  
+(no more problems due to `/var` not open for writing)
+
+Any changes in this system thus started will be lost when the system is rebooted/shutdown.
+
+To do this, it is necessary to modify the initramfs.  
+This means that any snapshot that does not include this modified initramfs will not be able to benefit from it.  
+(except for separate boot partitions)
+#
+### Installation :
+#### Arch Linux
+1.
+`Pacman -S grub-btrfs`  
+Or if you use git  
+copy the `overlay_snap_ro-install` file to `/etc/initcpio/install/grub-btrfs-overlayfs`  
+copy the `overlay_snap_ro-hook` file to `/etc/initcpio/hooks/grub-btrfs-overlayfs`  
+You must rename the files. (I did it above)
+
+For example :  
+`overlay_snap_ro-install` to `grub-btrfs-overlayfs`  
+`overlay_snap_ro-hook` to `grub-btrfs-overlayfs`  
+Keep in mind that the files must have exactly the same name to ensure a match.
+
+2.
+Edit the file `/etc/mkinitcpio.conf`  
+Added hook `grub-btrfs-overlayfs` at the end of the line `HOOKS`.
+
+For example :  
+`HOOKS=(base udev autodetect modconf block filesystems keyboard fsck grub-btrfs-overlayfs)`  
+You notice that the name of the `hook` must match the name of the 2 installed files. (don't forget it)
+
+3.
+Re-generate your initramfs  
+`mkinitcpio -P` (option -P means, all preset present in `/etc/mkinitcpio.d`)
+
+#### Other distribution
+Refer to your distribution's documentation  
+or contribute to this project to add a paragraph.
+#