add man page

This commit is contained in:
James Barnett 2017-02-03 13:54:03 -06:00
parent 03792597b0
commit b97cf5bf04
No known key found for this signature in database
GPG key ID: E4B5E45AA3B8C5C3
3 changed files with 235 additions and 234 deletions

View file

@ -26,3 +26,5 @@ install:
@install -Dm755 scripts/* -t $(SHARE_DIR)/libalpm/scripts/
@install -Dm644 hooks/* -t $(SHARE_DIR)/libalpm/hooks/
@install -Dm644 LICENSE -t $(SHARE_DIR)/licenses/$(PKGNAME)
@install -Dm644 man7/* -t $(SHARE_DIR)/man/man7
@install -Dm644 README.md -t $(SHARE_DIR)/doc/$(PKGNAME)

237
README.md
View file

@ -9,20 +9,7 @@ pre and post snapshot before and after pacman transactions, similar to how YaST
does with OpenSuse. This provides a simple way to undo changes to a system after
a pacman transaction.
* [Installation](#installation)
* [Configuration](#configuration)
* [Usage](#usage)
* [Example](#example)
* [Troubleshooting](#troubleshooting)
* [License](#license)
* [FAQ](#faq)
* [See also](#see-also)
## Installation
# pacman -S snap-pac
### PGP Key
## PGP Key
I have signed the release tarball with my PGP key. You may need to import my
public key before installation:
@ -31,224 +18,6 @@ public key before installation:
The key's fingerprint is `8535CEF3F3C38EE69555BF67E4B5E45AA3B8C5C3`.
## Configuration
## Documentation
Configuration is done via the snapper configuration files, with extra variables
specific to these pacman hooks. The defaults should be suitable for most users,
so you shouldn't need to change anything.
The following are possible settings you can place in each snapper configuration
file (*e.g.*, `/etc/snapper/configs/root`, etc.):
* `PACMAN_PRE_POST` - perform pacman pre/post snapshots for this configuration.
Default is `"no"` for all configurations, except for the `root` configuration
which is `"yes"`.
* `PACMAN_CLEANUP_ALGORITHM` - snapper algorithm used in cleaning up the pacman pre/post
snapshots. Default is `"number"`.
* `PACMAN_PRE_DESCRIPTION` - snapper description used for the pacman pre snapshot.
Default is the pacman command that called the snapshot.
* `PACMAN_POST_DESCRIPTION` - snapper description used for the pacman post snapshot.
Default is the pacman command that called the snapshot.
The following setting can be changed in the snapper configuration file
`/etc/conf.d/snapper`:
* `PACMAN_ABORT_ON_FAIL` - By default this is set to `"no"`. When set to `"yes"`
this causes pacman to abort a transaction if the snap-pac pre hook fails. This
prevents an upgrade/installation/removal from occurring if a pre snapshot cannot be
performed.
## 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. Additionally the snapshot numbers are output to the screen and to the
pacman log for each snapper configuration during the pacman transaction.
### Undoing a transaction
To undo changes from a pacman transaction, use `snapper undochange`. See the
snapper manpage and the following example.
If you have severe breakage—like snapper is gone for some reason and you can't
get it back—you'll have to resort to more extreme methods, such as taking a
snapshot of the pre snapshot and making it the default subvolume or mounting it
as `/`. Most likely you'll need to use a live USB to get into a chroot
environment to do any of these things. Snapper has a `snapper rollback` feature,
but your setup has to be properly configured to use it. The exact procedure
depends on your specific setup. Be careful.
## 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) Performing snapper pre snapshots...
home N/A
root 1033 ✓
:: Processing package changes...
(1/1) installing nano [######################################] 100%
:: Running post-transaction hooks...
(1/1) Performing snapper post snapshots...
home N/A
root 1034 ✓
The snapper snapshot number is given for each snapper configuration that is
used (tip: this is also logged in pacman's log). "N/A" means that configuration
is not set up for snap-pac (see above).
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
## Troubleshooting
**==> ERROR: One or more PGP signatures could not be verified!**
See [PGP Key](#pgp-key) on how to import my PGP key.
**ERROR: /etc/conf.d/snapper does not exist!**
*snap-pac* reads in the snapper configurations from `/etc/conf.d/snapper`. It
can't do that if the file doesn't exist. I'm not sure what you've done to not
have it exist in the default location.
**WARNING: No snapper configurations found, so not taking any snapshots!**
No snapper configurations were found in `/etc/conf.d/snapper`. This means you
haven't created any configurations yet using `snapper create-config`. See the
snapper manpage on how to do this.
**WARNING: No snapper configurations are set up for snapshots to be taken!**
Although you seem to have created at least one snapper configuration, none of
them are set up for *snap-pac*'s pacman hooks. By default *snap-pac* will take
snapshots for the `root` configuration and any other configuration which has
`PACMAN_PRE_POST` set to `yes` in its configuration file. This message means you
don't have a snapper configuration named `root` (or `PACMAN_PRE_POST` is set to
`no` for it) and no other configuration is set up for snapshots. See
[configuration](#configuration).
**WARNING: *prefile* does not exist, so no post snapshot will be taken. If you are initially installing snap-pac, this is normal.**
*snap-pac* saves the pre snapshot's number in a temporary file. Somehow it got
removed before the post snapshot could be taken. When you initially install
*snap-pac* the post hook is run, but the pre hook never was, so this message
will show up then as well and is safe to ignore in that circumstance.
**WARNING: Didn't find pacman running.**
The script gets the description from the pacman command that was run. If you get
this warning it looks like you may have run the script directly instead of
letting it run through pacman's hooks.
**ERROR: Unable to use snapper without dbus. Are you in a chroot environment?**
Snapper requires dbus. If you chroot into another environment, dbus will not be
available, so snapper can't take snapshots. Although snapper can be set up to
not need dbus, this is a simple way to check if one is in a chroot and avoid
attempting snapshots in it.
**After restoring snapshot from snap-pac, pacman database is locked**
The pre/post snaphots are taken while pacman is running, so this is expected.
Follow the instructions pacman gives you (*e.g.*, removing the lock file).
**snap-pac is only taking snapshots of the root configuration**
That's the default behavior. See [configuration](#configuration).
**Other problems**
If you have a problem not listed here, check the [open
issues](https://github.com/wesbarnett/snap-pac/issues) and file new issue if
your problem is not listed.
## FAQ
**Does snap-pac backup non-btrfs `/boot` partitions?**
Nope. See
[here](https://github.com/wesbarnett/snap-pac/issues/7#issuecomment-245593818)
for an example on how to set this up.
## License
snap-pac
Copyright (C) 2016, 2017 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`
See `man 7 snap-pac` after installation.

230
man7/snap-pac.7 Normal file
View file

@ -0,0 +1,230 @@
'\" t
.TH SNAP-PAC 7 2017-02-03 SNAP-PAC
.SH NAME
snap-pac \- Pacman hooks that use snapper to create pre/post btrfs snapshots
like openSUSE's YaST
.SH DESCRIPTION
This is a set of \fIpacman\fR hooks and script that causes \fIsnapper\fR to automatically
take a pre and post snapshot before and after pacman transactions, similar to
how YaST does with OpenSuse. This provides a simple way to undo changes to a
system after a pacman transaction.
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.
Additionally the snapshot numbers are output to the screen and to the pacman log
for each snapper configuration during the pacman transaction.
To undo changes from a pacman transaction, use \fIsnapper undochange\fR. See
\fBsnapper\fR (8) and the following example.
If you have severe breakage—like snapper is gone for some reason and you can't
get it back—you'll have to resort to more extreme methods, such as taking a
snapshot of the pre snapshot and making it the default subvolume or mounting it
as \fI/\fR. Most likely you'll need to use a live USB to get into a chroot
environment to do any of these things. Snapper has a snapper rollback feature,
but your setup has to be properly configured to use it. The exact procedure
depends on your specific setup. Be careful.
.SH CONFIGURATION
Configuration is done via the snapper configuration files, with extra variables
specific to these pacman hooks. The defaults should be suitable for most users,
so you shouldn't need to change anything.
The following are possible settings you can place in each snapper configuration
file (e.g., \fI/etc/snapper/configs/root\fR, etc.):
.BR PACMAN_PRE_POST
.RS
Perform pacman pre/post snapshots for this configuration.
Default is \fIno\fR for all configurations, except for the root configuration which
is \fIyes\fR.
.RE
.BR PACMAN_CLEANUP_ALGORITHM
.RS
Snapper algorithm used in cleaning up the pacman pre/post snapshots. Default
is \fInumber\fR.
.RE
.BR PACMAN_PRE_DESCRIPTION
.RS
snapper description used for the pacman pre snapshot. Default is the pacman
command that called the snapshot.
.RE
.BR PACMAN_POST_DESCRIPTION
.RS
snapper description used for the pacman post snapshot. Default is the pacman
command that called the snapshot.
.RE
The following setting can be changed in the snapper configuration file
\fI/etc/conf.d/snapper\fR:
.BR PACMAN_ABORT_ON_FAIL
.RS
By default this is set to \fIno\fR. When set to \fIyes\fR this causes pacman to
abort a transaction if the snap-pac pre hook fails. This prevents an
upgrade/installation/removal from occurring if a pre snapshot cannot be
performed.
.RE
.SH EXAMPLE
Installing the nano package as normal:
.EX
# 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) Performing snapper pre snapshots...
home N/A
root 1033 ✓
:: Processing package changes...
(1/1) installing nano [######################################] 100%
:: Running post-transaction hooks...
(1/1) Performing snapper post snapshots...
home N/A
root 1034 ✓
.EE
The snapper snapshot number is given for each snapper configuration that is used (tip: this is also logged in pacman's log). "N/A" means that configuration is not set up for snap-pac (see above).
And here are the snapshots:
.EX
# 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 |
.EE
What changed?
.EX
# 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
.EE
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:
.EX
# snapper -c root undochange 1033..1034
create:0 modify:3 delete:100
.EE
And nano is now gone, along with all the files it changed:
.EX
$ pacman -Qi nano
error: package 'nano' was not found
.EE
.SH TROUBLESHOOTING
.SS ERROR: \fI/etc/conf.d/snapper\fR does not exist!
snap-pac reads in the snapper configurations from \fI/etc/conf.d/snapper\fR. It can't
do that if the file doesn't exist. I'm not sure what you've done to not have it
exist in the default location.
.SS WARNING: No snapper configurations found, so not taking any snapshots!
No snapper configurations were found in \fI/etc/conf.d/snapper\fR. This means you
haven't created any configurations yet using snapper create-config. See the
snapper manpage on how to do this.
.SS WARNING: No snapper configurations are set up for snapshots to be taken!
Although you seem to have created at least one snapper configuration, none of
them are set up for snap-pac's pacman hooks. By default snap-pac will take
snapshots for the root configuration and any other configuration which has
PACMAN_PRE_POST set to yes in its configuration file. This message means you
don't have a snapper configuration named root (or PACMAN_PRE_POST is set to no
for it) and no other configuration is set up for snapshots. See configuration.
.SS WARNING: prefile does not exist, so no post snapshot will be taken. If you are initially installing snap-pac, this is normal.
snap-pac saves the pre snapshot's number in a temporary file. Somehow it got
removed before the post snapshot could be taken. When you initially install
snap-pac the post hook is run, but the pre hook never was, so this message will
show up then as well and is safe to ignore in that circumstance.
.SS WARNING: Didn't find pacman running.
The script gets the description from the pacman command that was run. If you get
this warning it looks like you may have run the script directly instead of
letting it run through pacman's hooks.
.SS ERROR: Unable to use snapper without dbus. Are you in a chroot environment?
Snapper requires dbus. If you chroot into another environment, dbus will not be
available, so snapper can't take snapshots. Although snapper can be set up to
not need dbus, this is a simple way to check if one is in a chroot and avoid
attempting snapshots in it.
.SS After restoring snapshot from snap-pac, pacman database is locked
The pre/post snaphots are taken while pacman is running, so this is expected.
Follow the instructions pacman gives you (e.g., removing the lock file).
.SS snap-pac is only taking snapshots of the root configuration
That's the default behavior. See \fBCONFIGURATION\fR.
.SH FAQ
.SS Does snap-pac backup non-btrfs /boot partitions?
Nope. But you can add hook that does it for you. It would be something like the
following:
.EX
[Trigger]
Operation = Upgrade
Operation = Install
Operation = Remove
Type = Package
Target = linux
[Action]
Description = Backing up /boot...
When = PreTransaction
Exec = /usr/bin/rsync -avzq --delete /boot /.bootbackup
.EE
.SH SEE ALSO
.BR alpm-hooks (5),
.BR snapper (8),
.BR pacman (8)
.SH AUTHORS
.MT https://github.com/wesbarnett
Wes Barnett