Git.

Keep all the config files of your tools in subdirectories of a git versioned directory and symlink them into their target location (e.g. with GNU stow). If installation of a tool is involved and you expect to have to revisit it, put the steps into an installation bash script and version it as well.

NixOS

Oh! I can participate!

Everything I have/configure is 100% in Ansible. I learned the hard way that rebuilding a workstation from scratch sucks if I only depend on my brain to remember things.

It takes some effort to keep it updated - if I'm trying out a new app, I have to remember to add it to my config.

The other thing that I've started doing is using Restic for file level backups. That's relatively easy to set up, it supports a multitude of backend storage, and works well with a cron job for braindead backups.

I just check my Nix.config, but most distros don't have that privilege.

Idk how it works for most other distros, but I know on Arch you can check all packages manually installed by pacman and your AUR helper.

Home Manager on a NixOS flake, it's a rabbit hole but I've been loving it since last week!

Install fresh copy of Linux OS on a new device. Install the apps I know I need like browser, code editor, etc.

Use device.

Realize "oh crap I forgot to install X!"

Install X

Repeat until all X have been installed.

Apart from those little tools running in the background that get their own little "How to install and configure X" file, I don't keep a list. I just install things as I need them, copying back config files from a backup. It's less annoying and time consuming than one might expect and keeps the system slim by not installing what I never use anyway.

Move all your heavily modified config files into a git repository and host it somewhere. Then symlink all your config files to where they should be with ln -s ~/.config/whatever ~/gitrepo/whatever. That's how you preserve your important configs.

You can easily get a list of your installed packages (which you can keep in your repository) with apt list --installed > packages.txt. You can then format that list to one you can install from with sed -e "s-/.*$--" <packages.txt (or something, i don't have apt, can't test it fully).

In fact, if someone here is more familiar with apt, please find a way to filter out packages that were not explicitly installed and reply to this comment with your solution.

Home manager on NixOS and stored all config files in a Git repo

Backup $home and /etc. That should be good enough.

Use ansible and variable, so it can be replicated to other computer. Simple

ansible.builtin.apt:
   name: "{{ item }}"
   state: latest
loop:
   - pkg1
   - pkg2

NixOS stores a snapshot of your OS and all the app configs in an OS config folder for you. Helpful for instant system recovery or deploying the setup to new hardware.

git repo

A bash script

apt get install

Same with flatpak

Keep updated. Done.

How do you keep track of what you’ve installed/ your favorite apps?

https://github.com/Atemu/nixos-config/blob/b79f42793a709db083cf53867f85d5d46e41eb69/packages.nix

Separately, how can I backup the configurations I’m using right now.

https://etckeeper.branchable.com/

I make a list of all the ones I like. Then when I feel my system is getting too bloated, I wipe and reinstall while only installing the packages from my list.

It’s very “low tech,” but it’s always worked out well for me.

I keep a changelog for all my computers and note installations, uninstallations and config changes.

https://github.com/koepnick/dotfiles cloned into ~/.config

I typically start with a restrictive .gitignore and add directories as needed.

A ton of stuff that I always forget like mpv, vifm, and whatnot always slipped through the cracks before. Now I can clone to practically anywhere and have everything just work.

Lately using Silverblue. Everything is a flatpak or is layered. Both are easy to list.

Maybe a handful of things in distrobox I need to keep track of.

If you use other package managers like flatpak, nix-env (for non-NixOS), npm (for global stuff), … you can just create a bash script to list all installed packages for each manager, and save to a file(s). I put them in a git repo to version control these lists, which are updated every now and then when I update stuff.

I use a notepad and write down the apps I mostly use so when I do a reinstall I just reference that.

I back up the entire system, apps and all. The main reason is so that I can get back up and running quickly, but it also spares me the need to worry about which apps to reinstall.

Mackup  https://github.com/lra/mackup

Ansible, although that may be overkill.

A dot files repo for some basic config and an Ansible repo to stand everything up. This applies to both my Linux and MacOS machines.

All the people taking about their NixOS setups had me thinking of giving that a try, though.

Write install and maintenance guides, save them somewhere public. Automation is good, but documentation and practicing technical writing is better.

I keep a .dotfiles folder in my home dir, use syncthing to back up those files on a couple of other computers, and then (on a new install) just make the actual config files symlinks to those files.

function pkglist -d "Gets list of installed packages"
  # Prevent descriptions in other languages
  set -l LANG C
  # Define pkglists location
  set -l dot $HOME/.config/dotfiles

  echo "(1/5) RPM-OSTREE status"
  rpm-ostree status > $dot/pkglist.rpm-ostree --booted

  echo "(2/5) Identify flatpaks"
  flatpak list --app --columns=application > $dot/pkglist.flatpak

  echo "(3/5) Identify pinned flatpak runtimes"
  flatpak pin > $dot/pkglist.flatpak.pinned

  echo "(4/5) Identify flatpak overrides"
  for i in (cat $dot/pkglist.flatpak)
      if test -s (flatpak override --show --user $i|psub)
	  echo $i
	  flatpak override --show --user $i
	  echo
      end
  end > $dot/pkglist.flatpak.overrides

  echo "(5/5) Save KDE configuration"
  fedora konsave -s kde_configuration --force

  # to apply configuration
  # fedora konsave -a kde_configuration

  git -C $dot st
end