When most people talk about killer applications they mean applications that will drive adoption. Taken literally, however, the phrase means the opposite: an application that kills adoption.
There's a clear leader among the candidates for that -and it's not limited to Linux. It's called Windows telnet and it's killed more Unix implementations than all other causes put together.
Is there anything dumber than using Windows telnet to administer Unix? is there anything more common? I mentioned my buddy "Larry" yesterday: he's got four people administering a pretty simple website using websphere on Red Hat - and every single one of them habitually logs on to those servers as root, using Windows telnet.
The right way, of course, is to use a Unix workstation with a big screen - that's why Sun still sells a 550Mhz USII with a 21 inch screen - and the GUI of your choice with remote X-windows.
For example, I have a love-hate relationship with HP-UX: the idiosyncracies and the lack of a decent csh drive me nuts, but I love the thing's reliability on PA-RSIC and have never had a problem trusting SAM (the X based sysadmin GUI) since 10.20 first came out. In one memorable case the client I was working for hired another consultant to set up two N-Class machines so MC ServiceGuard could be used. He was your classic gunslinger - wore a nice suit, talked the talk, used telnet on a laptop, and even slung the VG command line around with eclat. After a week or so, he declared victory and left in a puff of managerial acclaim - after which the other sysadmin and I found we had to reload those machines from the CD so Service Guard could actually work. We used SAM running in a pair of windows on my HP715/21" -then 12 years old and still working perfectly. It took us most of an afternoon -mainly because we including surface checking and reformatting for all the disks.
There's no love in my relationship with AIX, but it's stupid beyond belief not to use shitty on finicky (and there are no other kinds with AIX) configurations. And yet, this is what you see all the time. Serious people, many with real Unix skills, ignoring the GUIs to logon as root using Windows telnet and then cursing vi as unusable because the emulator doesn't handle composite VT220 sequences properly.
Both of those Unix variants, of course, are dead or dying, but the same affliction is being carried forward to Linux. I'm not that big a fan of webmin but at least it offers Windows users a safe GUI environment from which to administer many different flavors of Unix - including most of the major Linux variants. So why aren't people using it more?
I've tried, for example by introducing Larry to webmin and even demoing it in his boardroom -but I think his team's commitment lasted about until I left the room, then they went right back to using the Linux killer application: Windows telnet.