I have a script to sort a list of arbitrary hosts and determine if they are supported by grepping them into a master supported list. I cut all the suffixes of the hosts in the arbitrary list, leaving the "short" hostname if you will, then grep -w them into the master list. For example:

hosta.something.com becomes hosta, and hosta is grepped with -w into the master list. The master list may return something like hosta.anything.internal.com which is fine because that's the suffix our supported list uses.

However, there are some hosts on our list named hosta-1, hosta-1-10, hosta-b-svr and so forth. When I grep -w hosta it will return all those others because the grep is not delimited by a dash. This seems like a particularly difficult problem because if the arbitrary list DOES supply a hostname with a dash I still need to be able to grep that.

I think this is an impossible situation but just thought I'd ask.

Maybe I'm missing something, but is there a reason that dropping the -w and adding leading "whitespace" and a trailing dot would not work? Assuming that shortname holds the converted host name that you're searching for:

#if pattern is expected  any place other than the beginning of the line
grep "[ \t]${shortname}\."  master_file

# if pattern is expected as first token on line:
grep "^${shortname}\."  master_file