Arch Linux

jjt3hii

Member

Registered: 2008-06-09

Posts: 22

[solved] general updating question plus bonus rebooting question

Questions in reverse order of topic:

1.  How is one (an arch linux user) to know when updates require a reboot to take effect.  I understand if pacman updates me to a new kernel version I would need to reboot, but what about updates to other random packages? 

2.  This is probably not so much related to Arch, but linux in general:  How are packages actually updated when an application is in use?  For instance, if i'm currently running vlc and pacman updates it to a newer version, how does this actually take effect?  Are the updated files stored in a temporary location until they can override the files that are currently locked?  ...and if so, when does this happen, on reboot, on shutdown, on the process terminating?  ...and what process or subsystem actually manages this?

much love,

jason

Last edited by jjt3hii (2008-07-18 17:26:35)

josomebody

Member

Registered: 2008-06-20

Posts: 190

Re: [solved] general updating question plus bonus rebooting question

The updates are written to disk, overwriting the originals. The old version of the program, if it's still running is in RAM. Say you were running VLC, and while it was running got an upgrade of it. The old version is running, but if you stop it and run it again, it has to load the program from disk, so it'll be the new program.

The reason you reboot on a new kernel is because you can't very well unload it from ram and keep your system running well until it restarts.

I like to reboot if I change any configuration files that run on boot or sometimes if I'm playing with a new kernel module, to make sure I've got it set up to load properly on boot. Generally you only really need to reboot when you need a new version of something the system can't run without, such as the kernel.

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Mr.Elendig

#archlinux@freenode channel op

From: The intertubes

Registered: 2004-11-07

Posts: 4,092

Re: [solved] general updating question plus bonus rebooting question

I'm not really good at explaining stuff, but I'll give it a try:

1. Generaly, only a kernel update will requier a reboot. Almost all other updates only requier an restart of the spesific app, or at most, a log out/ log in.

2. The app will continue to run, because atleast parts of it are loaded to ram, and therefor, unaffected. You might experience some wierd behaviour if you tell the app to do something that requiers it to load or reaload part of itself. In any case, if you close the app, the next time you start it, it will be the new version that is executed. That is generaly also true if you open up a new instance of it, before you close the already running one.

Edit: In some rare cases pacman will tell you that you have to reboot the system cause of some upgrade, but it's a long time since that happened last, as I can remember.

Last edited by Mr.Elendig (2008-07-16 23:05:27)

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synorgy

Member

From: $HOME

Registered: 2005-07-11

Posts: 272

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Re: [solved] general updating question plus bonus rebooting question

Kernel updates tend to be the big culprits, but I've seen cases where my video driver required a reboot to take effect (but I believe this was paired with a kernel update, so the kernel may have been the culprit - I didn't investigate too much) . It's also nice to reboot when start up services are upgraded (fam, hal, mpd, alsa etc)

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klixon

Member

From: Nederland

Registered: 2007-01-17

Posts: 525

Re: [solved] general updating question plus bonus rebooting question

for daemons, a "/etc/rc.d/<daemon> restart" should work (to restart x, if you use gdm for instance: /etc/rc.d/gdm restart)
for modules, not included in the kernel package, a "modprobe -r <module> && modprobe <module>" should do the trick

both should be run as root

so only in case of a kernel update do you need to reboot

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jjt3hii

Member

Registered: 2008-06-09

Posts: 22

Re: [solved] general updating question plus bonus rebooting question

Thank you everyone.  It makes more sense to me now.

Jason

moberry

Member

Registered: 2008-08-08

Posts: 16

Re: [solved] general updating question plus bonus rebooting question

"sudo init s" should also do the trick. Kills all processes, brings the system into single user. Press CTRL-D to load it back up,