SysadmandineOne day, sysadmins will rule the world…

Here’s my linux favourite commands, by type :

Scripting
1. egrep : aaah… if I had to keep only one, this would be the one I’d choose… can’t spend 10 minutes without using it.
2. sed : because I always need to replace something by something else 10 times on each line in huge files
3. xargs : helps me avoid the for loop, shorter to write, easier to remember and understand when you find it in history
4. awk : for me the most difficult one to use, but I so know that it can do just what I want that I always take the time.

System
5. kill : ha ha, makes me feel I’m powerful
6. ps fauxww : makes me think I can watch everything that’s happening in real time. Like watching 10 movies at the same time.
7. aptitude : I like his way of telling me everything of what he’s doing… so chatty !
8. dstat : this one is really good : tells me a lot of things and with colors, I think he just knows what I’m looking for each time I call him.

Network
9. ssh : is it necessary to say something about it? without him I’d be nothing.
10. telnet : I like the raw output, no interpretation, he’s stupid and this is sometimes really appreciable
11. host : simple tool for so great usefulness, even the basic usage is perfect
12. nmap : I looove knowing everything about hosts I can’t access…
13. tcpdump : really useful when you really dont understand what’s happening.
14. netstat : nmap from the inside. Feels like a treasure hunt sometimes.
15. mtr : seems just easy and fast, but also gives a lot of interesting information.

Tools
16. vim : makes me save so much time
17. screen : How did they live before screen? And I use only a small amount of its potential…

Storage
18. fdisk : boring in the begenning, fun once you know it by heart
19. sfdisk : really handy to mirror a disk partitionning scheme
20. mdadm : I love mdadm. Just love it, don’t know why.

I have this very special server at work : a sunfire x4200 8 core 8GB RAM
To use the full given power, I tried to install xen on ubuntu, but it were freezing all the time. It seems to be a “TAP” problem, but I couldn’t fix it.
So I tried a Debian 5.0.3 dom0, and the problem is slightly different : now the domU won’t find its drives if I use “tap:aio”.
Ok, go back to the old “file:” driver.
This one is using loop devices to enable the drives, and only 8 default loop devices are enabled on debian (/dev/loop0 to /dev/loop7). As I want 7 domU, and at least 2 drives for each one (root and swap), I need more than 8 of these.
Here’s how to add more loop devices :
On Debian and ubuntu loop is a module, and you can specify the number of loop devices you want in /etc/modules. Replace :

by

(64 for example)

Then you have to disable the module :

and re-enable it :

But the new devices won’t append automatically for sure, so if you don’t see them in /dev/loop*, you can make them appear this way :
Edit /sbin/MAKEDEV and change :

By:

And execute

For me this step didn’t work either, so I had to create it really by hand :