Arch Linux

lucacerone

Member

From: Spain

Registered: 2012-05-04

Posts: 144

Website

Help with understanding better how pacman works.

Dear all,
I have recently installed Arch in a virtualbox guest machine and so far I am quite pleased with the experience.
I come from an Ubuntu background and there are a few things that I can't understand on how to use pacman.

Here are a few things I don't understand:
1) it is not clear to me if I have to always perform system upgrades or if I can upgrade only specific packages (if so how?)
2) Why is pacman -Syu safe, but pacman -Sy <a_package> can break things (at least this is what I read around)
3) I have noticed that if I do "pacman -S package" and the package is already installed, this is reinstalled in any case. I know the --needed option,
what I don't understand though is what happens when I install a package for which I already have some of the dependencies. Are they always reinstalled?
Is it safe to always use the "--needed" option?

Hope you can help me clarifying these things! Thanks a lot in advance,

Luca

GloW_on_dub

Member

Registered: 2013-03-13

Posts: 388

Re: Help with understanding better how pacman works.

1) Upgrade one package:

pacman -S package

2) From the wiki :
Warning: When installing packages, do not refresh the package list without upgrading the system (i.e. pacman -Sy package_name); this can lead to dependency issues. See #Partial upgrades are unsupported and https://bbs.archlinux.org/viewtopic.php?id=89328.

3) When you install a package, from wich you already some of the dependancies installed, it only install the uninstalled dependencies and the package itself, it does not reinstall anything.
However, the needed option can be usefull when you install a bunch of packages, copied from internet for example, and you don't know if some of these package are already installed, using needed option will allow you not to reinstall already installed package.