Friend is interested to learn Linux Sys admin, will it help for his Career 4668

Probably won't hurt. Linux is used forsomethingin most networks. There is a mbuttive shortage of *good* Linux-Unix people. I don't know poo and I haven't yet met anyone who could compete with me in the offline world.

Can somebody sugest what are main things to learn System

Shell and perl scripting. Many things are done with scripts that you build on your own. This necessitates a firm understanding of the shell, its commands, and basic commands in a unix system like awk, grep, find, tar, rsync, etc...

Theory of TCP-IP networking and routing.

The security advisory method of your distribution and others.

Compiling programs from source and working with developers to debug and fix problems.

Building a kernel from scratch to do what you want and only what you want.

Some amount of security theory and firewall manipulation including knowing where services are, which ones to never use, and how to turn them on-off.

Knowing not only what RTFM means but knowing HOW to RTFM, FTFM, and DAFGS.

Being familiar with more than just Linux but also SCO, Solaris, etc...and on top of that being able to work with Windows and possibly Mac systems...and figuring out why they won't talk with your unix server the way you think they should...especially the windows systems.

And #1 thing you need to develop is an inquisitive mind and desire to figure things out. A good Linux admin is also at least a halfway decent hacker (not cracker) and understands how computers think (or more to the point - don't think).

Ability to write decent documentation not just for others but also for yourself so you can remember how the f*** you got something to work last time.

The ability to summon daemons of all types and natures is also not a bad thing. Black magic fixes problems more often than any white science.