133 lines
4.8 KiB
Markdown
133 lines
4.8 KiB
Markdown
# snap-pac
|
|
|
|
This makes Arch Linux's pacman use
|
|
[snapper](https://wiki.archlinux.org/index.php/Snapper) to automatically take a
|
|
pre and post snapshot before and after pacman transactions using pacman's hooks
|
|
feature, similar to how YaST does with OpenSuse. This provides a simple way to
|
|
undo changes to a system after a pacman transaction.
|
|
|
|
The snapshots are set up to use snapper's `number` algorithm. That is, snapper
|
|
will periodically clean up snapshots tagged with `number` after reaching a set
|
|
threshold in the snapper configuration file.
|
|
|
|
**Note:** Snapshots are only taken of the subvolume corresponding with the
|
|
`root` snapper config; other subvolumes are not included. You must modify the
|
|
scripts to include other subvolumes. Additionally, you should create subvolumes
|
|
of directories you do *not* want included in your snapshots (*e.g.*
|
|
`/var/cache/pacman/pkg`).
|
|
|
|
## Installation
|
|
|
|
Install [the package from the
|
|
AUR](https://aur.archlinux.org/packages/snap-pac/).
|
|
|
|
After installation, the hooks are located at `/usr/share/libalpm/hooks`, and the
|
|
scripts are located at `/usr/share/libalpm/hooks.bin/snap-pac`.
|
|
|
|
## Usage
|
|
|
|
### Taking snapshots
|
|
|
|
**Use pacman—and AUR helpers—as normal and watch snapper do its thing.** No
|
|
bash scripts for you to call. No bash aliases to setup.
|
|
|
|
Because these are pacman hooks, it doesn't matter how you call pacman—whether
|
|
directly, through an AUR helper, or using an alias—snapper will create the
|
|
snapshots when pacman installs, upgrades, or removes a package. The
|
|
pacman command used is logged in the snapper description for the
|
|
snapshots.
|
|
|
|
### Undoing a transaction
|
|
|
|
To undo changes from a pacman transaction, use `snapper undochange`. See the
|
|
snapper manpage and the following example.
|
|
|
|
## Example
|
|
|
|
Installing the `nano` package as normal:
|
|
|
|
# pacman -S nano
|
|
resolving dependencies...
|
|
looking for conflicting packages...
|
|
|
|
Packages (1) nano-2.5.3-1
|
|
|
|
Total Installed Size: 2.14 MiB
|
|
|
|
:: Proceed with installation? [Y/n] Y
|
|
(1/1) checking keys in keyring [######################################] 100%
|
|
(1/1) checking package integrity [######################################] 100%
|
|
(1/1) loading package files [######################################] 100%
|
|
(1/1) checking for file conflicts [######################################] 100%
|
|
(1/1) checking available disk space [######################################] 100%
|
|
:: Running pre-transaction hooks...
|
|
(1/1) snapper pre snapshot
|
|
:: Processing package changes...
|
|
(1/1) installing nano [######################################] 100%
|
|
:: Running post-transaction hooks...
|
|
(1/2) snapper post snapshot
|
|
(2/2) generate GRUB configuration file
|
|
|
|
And here are the snapshots:
|
|
|
|
# snapper -c root list -t pre-post | tail -n 1
|
|
1033 | 1034 | Fri 22 Apr 2016 01:54:13 PM CDT | Fri 22 Apr 2016 01:54:14 PM CDT | pacman -S nano |
|
|
|
|
What changed?
|
|
|
|
# snapper -c root status 1033..1034
|
|
+..... /etc/nanorc
|
|
c..... /etc/snapper/.snap-pac-pre
|
|
+..... /usr/bin/nano
|
|
+..... /usr/bin/rnano
|
|
+..... /usr/share/doc/nano
|
|
+..... /usr/share/doc/nano/faq.html
|
|
+..... /usr/share/doc/nano/fr
|
|
+..... /usr/share/doc/nano/fr/nano.1.html
|
|
+..... /usr/share/doc/nano/fr/nanorc.5.html
|
|
+..... /usr/share/doc/nano/fr/rnano.1.html
|
|
|
|
|
|
I truncated the above output, but it continues. See the manpage for snapper to
|
|
see what each symbol means. You can also do `snapper diff` in the same
|
|
way—I'll spare you that one.
|
|
|
|
To undo the upgrade:
|
|
|
|
# snapper -c root undochange 1033..1034
|
|
create:0 modify:3 delete:100
|
|
|
|
And `nano` is now gone, along with all the files it changed:
|
|
|
|
$ pacman -Qi nano
|
|
error: package 'nano' was not found
|
|
|
|
## License
|
|
|
|
snap-pac
|
|
|
|
Copyright (C) 2016 James W. Barnett
|
|
|
|
This program is free software; you can redistribute it and/or modify
|
|
it under the terms of the GNU General Public License as published by
|
|
the Free Software Foundation; either version 2 of the License, or
|
|
(at your option) any later version.
|
|
|
|
This program is distributed in the hope that it will be useful,
|
|
but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
GNU General Public License for more details.
|
|
|
|
You should have received a copy of the GNU General Public License along
|
|
with this program; if not, write to the Free Software Foundation, Inc.,
|
|
51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
|
|
|
|
## See also
|
|
|
|
* [ArchWiki Btrfs article](https://wiki.archlinux.org/index.php/Btrfs)
|
|
* [ArchWiki Snapper article](https://wiki.archlinux.org/index.php/Snapper)
|
|
* [Btrfs homepage](https://wiki.archlinux.org/index.php/Btrfs)
|
|
* [snapper homepage](http://snapper.io/)
|
|
* `man alpm-hooks`
|
|
* `man btrfs`
|
|
* `man snapper`
|