pacpush is a simple command line utility which Arch Linux users can use to manually push pacman and AUR helper Arch Linux package updates to other machines to avoid having to download them more than once via the web.

My use case follows as a good example of what this utility is for.

I update my main Arch PC and my Arch laptop every day using yay. Previously, I would update either both machines in parallel, or one before the other. So both machines would download the package lists from the web, then download and install the out of date system packages, then download, build, and install all out of date AUR packages. This takes quite some time, particularly on a slow internet connection, and it is inefficient to be downloading and building most packages twice for the same architecture machines.

Using pacpush, I now update my PC first then after that update has finished I run pacpush lt on my PC to update lt directly via my local LAN. Pacpush pushes the updated package lists, then queries lt to work out which packages lt has out of date (including AUR packages), then pushes all the system and AUR packages that it has which lt needs.

After running pacpush, I run a yay update on lt and it completes very quickly because lt only needs to download the system and AUR packages my PC did not have. I typically use very similar system and AUR packages on both machines so typically lt doesn't need to download or build any updated AUR packages at all.

Obviously this only works for machines of the same architecture, i.e. compatible package files, so pacpush checks for this before pushing any files.

You need to have root ssh access to the remote machines for pacpush to work. See the SSH AND KEY CONFIGURATION section below on how best to set this up.

If you specify multiple hosts then the program will update them in parallel. You can limit, or increase, the number of parallel updates using the -p/--parallel-count option. Update messages are output in a unique color for each host.

Note that pacpush should work with any AUR helper so long as you set --aur-build-dir appropriately in your configuration file, see the CONFIGURATION FILE section below for details.

The latest version and documentation is available at https://github.com/bulletmark/pacpush.

To solve this problem, I originally started using pacserve which is what is usually recommended for this use case. However pacserve does not sync the package lists nor does it do anything about AUR packages which is particularly unfortunate because AUR package downloads often include huge source and other files and can require long build times. Since pacpush pushes the entire AUR directory for each required package, the second machine benefits by typically not having to download or rebuild any updated AUR packages at all.

Just install pacpush from the AUR to the local and remote hosts.

Note pacpush is also available on PyPI if you prefer so just ensure that pipx is installed then type the following to install on each machine. Requires Python 3.8 or later.

$ pipx install pacpush

To upgrade:

$ pipx upgrade pacpush

You run pacpush directly on the command line as your normal user, not as root and not using sudo explicitly. You specify as arguments the host, or hosts, you want to update. The utility will re-invoke itself using sudo and will push the required package updates.

You need to set up root ssh access from your host machine to the remote machine[s] for this to work. For security and convenience, it is essential to use an ssh key. The following procedure copies your personal public ssh key to the remote root account. Your first need to set up your own personal ssh key pair of course, see Google for that part.

On a remote host to which you want to pacpush (assuming you have already set up personal ssh access to that host):

$ sudo mkdir -p /root/.ssh
$ sudo chmod 700 /root/.ssh
$ sudo cp ~/.ssh/authorized_keys /root/.ssh

# Possibly remove any keys you don't want root to allow if you have
# more than one:
$ sudoedit /root/.ssh/authorized_keys

Note that the sudo invoked by pacpush on itself when you run it as your normal user passes on $SSH_AUTH_SOCK so that the remote root ssh session authenticates against your personal ssh key.

For rsync/ssh configuration convenience, rsync and ssh commands run by root are specified with your personal user's ssh configuration file ~/.ssh/config if it exists (unless you specify an explicit --ssh-config-file for pacpush usage as described in the next section). Note rsync and ssh commands run on behalf of root user explicitly specify target root@host so that any User specification in your personal ssh configuration for any host is ignored.

⚠️ From pacpush version 3 onwards, the format of the ~/.config/pacpush/pacpush.conf file has changed from YAML to a simple text file where you specify any of the pacpush startup options.

You can add default options to a personal configuration file ~/.config/pacpush/pacpush.conf. If that file exists then each line of options will be concatenated and automatically prepended to your pacpush command line arguments. Comments in the file (i.e. starting with a #) are ignored. Type pacpush -h to see all supported options. The configuration file is read for the invoking user only on the local host client machine. The configuration file is ignored on any remote machine you are pushing to (because all required options are passed from the client).

You may want to change the --aur-build-dir setting which is the location of your AUR helpers download/build directory. This is the directory from which AUR packages are rsync'd from the local host to remote hosts. --aur-build-dir can be set to a single directory string, or a list of directories by inserting a ";" between multiple directory names. Ensure that --aur-build-dir is set to, or at least contains, the build directory your AUR helper uses. Directories which don't exist are ignored.

Example Settings

The default configuration is to sync many of the common AUR helper directories that exist on your host machine. See the default --aur-build-dir directories listed by pacpush -h. Pacpush will sync packages in each --aur-build-dir directory which exists, and is pending an update. E.g. if you were using trizen some time ago, and am now using yay instead, then you could keep this default setting and just do a rm -rf ~/.cache/trizen because pacpush ignores --aur-build-dir directories which don't exist. Or you could just set --aur-build-dir ~/.cache/yay in your ~/.config/pacpush/pacpush.conf which is the slightly more efficient approach.

You can also create and specify a custom --ssh-config-file file. This allows you to specify ssh settings for pacpush use, either globally, or for each host. See man ssh_config for details on how to specify ssh (including per host) settings. If the specified --ssh-config-file path is relative then it is taken to be relative to ~/.config/pacpush/.

Any of the options specified in the next Usage section can be specified in ~/.config/pacpush/pacpush.conf.

Type pacpush -h to view the usage summary:

usage: pacpush [-h] [-b AUR_BUILD_DIR] [-n] [-m] [-p PARALLEL_COUNT] [-u]
                  [-s] [-a] [-C] [-N] [-M] [-F SSH_CONFIG_FILE] [-V] [-d]
                  [hosts ...]

Utility to push this Arch hosts system and AUR package caches to other host[s]
to avoid those other hosts having to download the same new package lists and
updated packages, at least for shared common packages. Requires root ssh
access to other hosts (it is easier with an auth key).

positional arguments:
  hosts                 hosts to update

options:
  -h, --help            show this help message and exit
  -b AUR_BUILD_DIR, --aur-build-dir AUR_BUILD_DIR
                        AUR build directory[s]. Can specify one, or multiple
                        directories separated by ";". Default is "~/.cache/yay
                        ;~/.cache/paru/clone;~/.cache/trizen;~/.cache/pikaur/a
                        ur_repos;~/.cache/aurman". Non-existent directories
                        are ignored.
  -n, --dryrun          dry run only
  -m, --no-machcheck    do not check machine type compatibility
  -p PARALLEL_COUNT, --parallel-count PARALLEL_COUNT
                        max number of hosts to update in parallel. Default is
                        10.
  -u, --updates         just report all installed packages with updates
                        pending, including AUR packages
  -s, --sys-only        only sync/report system packages, not AUR
  -a, --aur-only        only sync/report AUR packages, not system
  -C, --no-color        do not color output messages
  -N, --no-color-invert
                        do not invert color on error/priority messages
  -M, --mirrorlist      also sync mirrorlist file
  -F SSH_CONFIG_FILE, --ssh-config-file SSH_CONFIG_FILE
                        ssh configuration file to use. Default is
                        "~/.ssh/config" (if it exists).
  -V, --version         show pacpush version
  -d, --debug           output debug messages

Note you can set default starting options in
$HOME/.config/pacpush/pacpush.conf.

Copyright (C) 2017 Mark Blakeney. This program is distributed under the terms of the GNU General Public License. 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 3 of the License, or 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 at http://www.gnu.org/licenses/ for more details.