Cargo Cult sysadmining

[Roberto Ragusa]

On 08/07/2012 01:40 PM, Tom Horsley wrote:
> So here's one that always leaves me wondering: The #1 original
> admin advice that *ought* to be Cargo Cult except for the
> fact that it actually works quite often: "reinstall the
> program".
> 
> It is recommended far more often on Windows than on Linux,
> but I see folks say it on Linux as well, and the totally
> absurd thing is that it often works.
> 
> Why should it work? If a computer doesn't work well enough
> to do a simple job like copy a few files off some install
> media reliably, why on earth would you trust it to run
> the (probably) much more complicated program you just
> installed? In fact, if copying a few files onto the system
> fails so often that reinstall is a standard practice, why
> does anything ever work at all? It is a mystery to me :-).

Reinstalling a program on Linux is almost always useless.
If a "rpm -V" comes out clean, you will not get very far
with a reinstall.

On Windows it usually works because of poor handling of
dependencies and DLL-hell (reinstalling forces your pieces
in place again) and because installation and configuration
are always blended together [reinstall => lose (damaged) settings].

On Linux, sometimes it works, simply because of side
effects: SElinux labeling or post-install scripts which are
repairing something.
A much more useful thing to do is to delete the settings
of the program in your home dir.
Better yet, just rename them. If they are too complicated,
create a new user and test again; if it works, now
start copying your setting to this account and retest
until it breaks, so you know where the real problem is.

My contribution to the cargo cult list:

"do not interfere with my attempts to break everything":

- "yum -y"
- "rpm --force"
- "rpm -e --force"

"let's put things which will break at next update (or sooner)":

- oracle JVM rpm or tar
- nvidia/fglrx driver
- vmware modules
- interfering stuff compiled from source (php, mysql, httpd, ...)
- manual symlinks here and there

-- 
   Roberto Ragusa    mail at robertoragusa.it