This is something I ran into recently over the weekend. I made modifications to the DNS of a domain and I couldn't get my mac to recognize the change.
The culprit was DNS caching, after flushing my DNS cache all was well.
# dscacheutil -flushcache
A friend of mine had a question on how to edit a huge (like as in xbox hueg) file without using vi. He probably didn't want to use vi because when you vi a file it will load the entire file into memory. This can be very bad if your system doesn't have enough memory to accommodate the file size.
So how do you edit a specific line of a file without loading it into memory?