Saturday, July 10, 2010
linux administration - tips, notes and projects
So, often I’ll come across something that I need done, but don’t want to waste time manually doing it. This particular instance, I had a list of hostnames which I needed to remove the trailing “.” (dot) from the PTR. Normally, if these hostnames were all simple name.TLD domains this would easily be accomplished with cut:
cut -d. -f1-2
This basically means cut by delimiter (-d), where the delimiter is defined as a period (.) and then print fields 1 and 2. Easy enough.
But, what if you have hostnames and subdomains with varying field lengths, such as: something.domain.com. and something.else.domain.com.
So — here’s two easy ways to get it done.
This one’s for you vi fans (and once again pains me to learn another way that vi is more capable than nano/pico):
Run that in vi, and wha-la, all the trailing dots disappear. You can obviously do this for other characters that are not “dots” by replacing the . in the command above.
But wait, there’s still more ways to skin the
sed. x=`echo $i|sed s/.$//`
Either way, this leaves you with an easy way to save yourself boatloads of time (depending on how long the list you’re trying to trim is!)
Hope this helps!