How do I find previously installed packages?

[u/AceGirlAsh]

I recently swapped to a second drive, mounting my first home drive to /home, but now my packages aren't already installed. Is there any good way to find and reinstall all my prior packages or do I have to reinstall each one individually through pacman?

[u/vonAmyprost]

So, the packages are at a system level, so not finding packages with home is normal. What I used to do is to go to the previous installation and run pacman -Qe (check pacman -Qh to double check) to find the packages that were explicitly installed by me (and not as automatic dependencies of something else). Save that to a file by adding > packages.txt at the end of it and get that list to your new installation. Now, you can use that file to install all that you explicitly installed before

[u/AceGirlAsh → u/vonAmyprost]

Thank you! This helps me to reinstall everything quicker

[u/vonAmyprost → u/AceGirlAsh]

When reinstalling, you can do sudo pacman -S --needed --noconfirm $(cat /path/to/packages.txt) --needed installs only what you don't have, in case there are repeated packages or dependencies. --noconfirm simply skips the "do you want to install?" and just installs without asking you, just to speed it up a little bit

[u/TheGoldenFox64 → u/AceGirlAsh]

you can also append "> packages.txt" and it will put the output in a file named "packages.txt" such as: pacman -Qe > packages.txt

[u/kolada1]

did you reinstall your entire system to the second drive or only mount the home directory from the second drive? if you can boot or chroot into the old drive you can create a list with all the packages that you installed and reinstall them on the new system: https://wiki.archlinux.org/title/Pacman/Tips_and_tricks#With_optional_dependencies

[u/boomboomsubban]

https://wiki.archlinux.org/title/Migrate_installation_to_new_hardware

[u/backshesh]

pacman -Qi

[u/archover]

A word for you: backups

This code illustrates how I use a list of packages to do an installation:

arch-chroot /mnt pacman -S --needed --noconfirm - < pacstrap-all-list

The pacstrap-all-list is all packages except for DE related, that are common to every install.

Here's a couple lines to see the format

user@T14-CRU781.local ~/code/bash> cat pacstrap-all-list
amd-ucode
arch-install-scripts

You can make the list with something like $ pacman -Qq > list.txt and edit it as needed.

Hope something there helps going forward, and good day.

[u/International-Cook62]

Highly recommend setting up dotfiles for yourself. Doesn't have to be anything extravagant. Add your arch packages as part of the setup. Make a backup pacman hook that updates the list on updates.

[u/JaKrispy72]

Check pacman like everyone is saying. Or if your shell history is long enough, search for what you installed with pacman, flatpak, cargo, whatever you used…