A brief introductions to the intricacies of Archlinux

Jagged · 2003-08-18 05:19:58

_JeffG_ 's post gave me an idea to start this... i know the developers are busy, so I figured we could start a thread here with the intricasies of how ArchLinux is set up. For example; I've spont a lot of time in /etc/ so here's what I've found out:

/etc/pacman.conf
Repositories
This is the configuration file for pacman. the package manager for achlinux.
As per default you can only access packages in the 'official' repository. To gain access to the multitude of packages available in the unofficial repository look around line 48, there will be a section that looks like:

# Uncomment this block to access the 'unofficial' package set
#
[unofficial]
#Server = ftp://ftp.ibiblio.org/pub/linux/distributions/archlinux/unofficial
#Server = ftp://ftp.webtrek.com/pub/mirrors/archlinux/unofficial
#Server = ftp://ftp.archlinux.org/unofficial
#Server = ftp://ftp.mpi-sb.mpg.de/pub/linux/mirror/ftp.ibiblio.org/pub/Linux/distributions/archlinux/unofficial
#Server = ftp://ftp.oit.unc.edu/pub/Linux/distributions/archlinux/unofficial
#Server = ftp://ftp.tu-chemnitz.de/pub/linux/sunsite.unc-mirror/distributions/archlinux/unofficial
#Server = ftp://ftp.parrswood.net/Mirrors/ftp.archlinux.org/unofficial
#Server = ftp://gd.tuwien.ac.at/opsys/linux/archlinux/unofficial
#Server = ftp://saule.mintis.lt/pub/linux/unofficial
#Server = ftp://ftp.rez-gif.supelec.fr/pub/Linux/distrib/archlinux/unofficial

Uncomment (remove the # marks) that section to gain access to the unofficial repository.
Note: there are also 'stable' and 'unstable' repositories as well, read the short documentation in the file for information on those.
Also Note: User-created packages are available at ftp://ftp.archlinux.org/incoming/. It is common practice to post here: http://bbs.archlinux.org/viewforum.php?f=25 when a new package is submitted.

Options
At the beginning of the /etc/pacman.conf file is the options section, which by default looks like:

#
# GENERAL OPTIONS
#
[options]
NoUpgrade = etc/passwd etc/group etc/shadow
NoUpgrade = etc/fstab etc/rc.conf etc/rc.local
NoUpgrade = etc/lilo.conf etc/raidtab
#IgnorePkg = lilo gcc

It is in this section we can setup a few more options for pacman. Here is a list of currenty available options:
DBPath = /path/to/db/dir
Overrides the default location of the toplevel database direc-tory. The default is /var/lib/pacman.

IgnorePkg = <package> [package] ...
Instructs pacman to ignore any upgrades for this package when performing a --sysupgrade.

NoPassiveFtp
Disables passive ftp connections when downloading packages. (aka Active Mode)

NoUpgrade = <file> [file] ...
All files listed with a NoUpgrade directive will never be touched during a package install/upgrade. Note: do not include the leading slash when specifying files.

NoUpgrade is what you would use for system critical config files and whatnot.

How pacman deals with config files

This is my understanding from experience (and the manpage) with how pacman will handle config files under different cases.

1) Removing a package

Pacman creates a backup of the config file with a .pacsave extension. For example, when i installed metalog and removed syslog, pacman moved /etc/syslog.conf to /etc/syslog.conf.pacsave

2) Upgrading a package (heres the tricky part)

pacman uses creates three md5sums to figure out what to do.

md5sum #1 = original config file in the original package installed before the upgrade
md5sum #2 = current config file thats actually in use by the system
md5sum #3 = new config file with the updated package that is not yet installed

if original == current == new (e.g. all files are the same) then the new one is isntalled
if (original == current) != new (e.g. original config was not changed, but the new one is different) then install the new one, for it might have new features, bugfixes, etc.
if (original == new) != current (e.g. the default config file has not changed between the original and new packages, but the user has modified their config) then do nothing (to preserve the users settings)
if (original != current) && (current != new) && (original != new) (e.g. all config files are different) then create a .pacsave of the current and install the new one

That's all i have to say for tonight. Maybe tomorrow I'll write something about understanding the startup scripts.

Jagged · 2003-08-18 05:48:00

Allright I'm bored, so im going to outline some stuff some people may want to know:

/etc/login.defs
Nifty little file here.

Line 80 defines where root logins will be allowed

For those users that like having a wheel group (only users on the wheel group can su) look at line 228. Note, if you are setting up a wheel group, the wheel group has GID 0, which in ArchLinux has the name 'root'... not wheel. So, any users that need su should be added to that group (remember to add yourself with usermod -G users,groupsgohere,root username)

Lines 217-220 defines password aging

line 250 sets the maximum number of bad login attempts
255 sets the login timeout
260 sets the maximum tries for a password change

rasat · 2003-08-18 05:54:11

Jagged wrote:

I figured we could start a thread here with the intricasies of how ArchLinux is set up.

The core of Arch Linux is /etc/inittab and it's related /etc/rc.xxx files.

Jagged · 2003-08-18 06:02:13

allright... maybe im not done

How to set up the correct timezone
Allright, I like my computer in UTC (even though im in EST/EDT) but some people don't like having to deal with offsets, so here's how to fix it.

1st step:
determine what time your hardware clock is.
easiest method to do this is enter your bios setup and look at the time displayed. If it's the same as your local time, remember that. If it isn't figure out if it's UTC from your UTC offset, for instance EST is UTC -500... (EDT is -400... daylight savings). If that isn't possible, or it's incorrect, just set the clock to your local time.

2nd step:
edit /etc/rc.conf on line 12
this lets the system know how your hardware clock is set up enter "UTC" or "localtime" as per the results of step one

move to line 11
now you choose your timezone
look in /usr/share/zoneinfo/ for your timezone
when setting this i prefer to use the subdir system: e.g. EST/EDT is America/New_York, etc
remember what you finally decided on

3rd step
make a symlink from /etc/localtime to the zonefile you chose in step 2

Jagged · 2003-08-18 06:04:29

The core of Arch Linux is /etc/inittab and it's related /etc/rc.xxx files.

my bad.... im going off on a tangent, but im seeing a lot of the same things in #archlinux, seems like some of the newer users aren't exactly the intended audience.

Jagged · 2003-08-18 06:08:50

i dont quite know how to use latex/tex

still no excuse though.

Jagged · 2003-08-18 16:07:10

Allright, I'm working on the latex thing. You can see the most current version at http://aias.no-ip.info/archguide.latex

dont sue me if it breaks going through latex though

Jagged · 2003-08-18 17:45:22

Got an html version of the work-in-progress: http://aias.no-ip.info/archlinux-guide/

Jagged · 2003-08-21 04:25:33

Version 0.1 of my (unofficial) ArchLinux Detailed Descriptor Guide will be finished tomorrow by 20:00 UTC (2003-08-21). Check it out at http://aias.no-ip.info/archlinux-guide/

Version 0.1 includes the following topics:
how pacman works and how to use it properly
how the init structure of ArchLinux works, descriptions of how init works, inittab walkthrough, and explanations of the rc scripts (all of this is as per my dissection of the files, developers feel free to correct any incorrect information)

as of right now (04:23 UTC 2003-08-21) the inittab section is 99% done, and the rc's need to be added, but all will be done by the deadline i have posted.

be warned, right now the doc is on my box (cable connection) so its gonna be a little slow.

a pdf version will be available at http://aias.no-ip.info/archlinux-guide/ … -guide.pdf

dp · 2003-08-21 12:41:30

need help in LaTeX? ... for the beginning use
"Kile" (in incoming) ... it is much easier to start with LaTeX with it, as it can offer you some predefined lines to start usiing it .... the only thing i have to say additionally:

% is the comment-sign

%after 
/begin{document}
%you can start writing things down

/section{Title}
Here comes normal text

/subsection{Subtitle}
Here text

everything else you can use out of kile ... like a word-processing tool :-)

Jagged · 2003-08-21 19:42:37

vim suits me fine

Arch Linux

#1 2003-08-18 05:19:58

A brief introductions to the intricacies of Archlinux

#2 2003-08-18 05:48:00

Re: A brief introductions to the intricacies of Archlinux

#3 2003-08-18 05:54:11

Re: A brief introductions to the intricacies of Archlinux

#4 2003-08-18 06:02:13

Re: A brief introductions to the intricacies of Archlinux

#5 2003-08-18 06:04:29

Re: A brief introductions to the intricacies of Archlinux

#6 2003-08-18 06:08:50

Re: A brief introductions to the intricacies of Archlinux

#7 2003-08-18 16:07:10

Re: A brief introductions to the intricacies of Archlinux

#8 2003-08-18 17:45:22

Re: A brief introductions to the intricacies of Archlinux

#9 2003-08-21 04:25:33

Re: A brief introductions to the intricacies of Archlinux

#10 2003-08-21 12:41:30

Re: A brief introductions to the intricacies of Archlinux

#11 2003-08-21 19:42:37

Re: A brief introductions to the intricacies of Archlinux

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