Checking for the existence of domains from commandline in Bash

while read line; do wget --quiet --spider --timeout=10 $line; if [ $? -ne 0 ]; then echo $line; fi; done < "/tmp/domains.txt" 
/tmp/domains.txt would hold the list of domain names separated by newline.
Note this is just a quick hack and not entirely reliable.

myisamcheck running out of tmp space

Recently I was running myisamcheck on an entire database housed inside a vserver. And, by default vserver mounts a 16MB ramfs on /tmp. This obviously is not an ideal solution when you are running a DB server that has a few tables that are around 20GB. So I had to specify a different directory for storing temporary files – that was on a partition with enough space – while running myisamcheck. To do that I had to make use of the –tmpdir parameter defined here.

Also, the way to increase the /tmp size inside a vserver seems to be this. I have not tested that solution yet.