New interview question
One of our customers decided to send us a more unusual christmas card in the form of a puzzle. It was this,
if you do
cd /dev mv *. *..
how do you restore the system to a working state?
To add hypothetical pressure to this hypothetical question imagine that the users of the hypothetical server had just done a major press launch.
Our answer was, if your hypothetical panicking system administrator had bought our managed service we could restore it from backup. As a favour we’d even restore the backup to a new virtual server allowing us to keep the filesystem on the old machine so we’d have a chance of pulling out any missing updates that had happened since the backup that morning. We could then merge it all back on to the original platform at a slightly less stressful time.
Happily our backup and restore procedures do get tested, so we were able to fairly straightfowardly restore from the backup server, build the new VDS and bring it up running the site.
One thing our newest employee didn’t know was about the usefulness of netcat so I was able to make him one of todays lucky 10,000.[*] If you’re running a debian install CD you’ll notice it doesnt have ssh or rsync but does have netcat. Consequently you can transfer your data nice and quickly as follows,
backup# iptables -I INPUT 1 -p tcp -s
backup# cat backed-up-filesystem.tar.gz | nc -p xxx -l
target# nc -p xxxx
backup# iptables -D INPUT 1
As always, if you read this and think “that’s clever, I wonder if I’d have thought of that” you should take a look at our managed services. If you’d definitely done it better[**] then we invite you to show off at our puzzle.
[*] Scaling for the UK birth rate rather than the US one he’s one of todays lucky 1,600. You’d have to be pedantic even by the standards of system administrators to complain about that though.
[**] Before some points out that tar has a z flag we are aware of that. However computers have lots of processors and this way tar / gunzip / nc can all sit on different cores and make it go faster which is important if you’ve people waiting for the site to come back up.