So I'm stumped.
First... APOLOGIES... my work is offline in an office that has zero internet connectivity, as required by our client. If need be, I could print out my script attempts and retype them here. But on the off chance... here goes.

I have a text file (file_source) of terms, each line could have one, two or more words in this file.
I want to use each line from file_source as a key to grep for in a different file, (file_target)
I want to run a script that reads file_source, and uses the words from each line, to search/grep in file_target.
IE: grep "one first word" file_target, or just grep "second" file_target, etc.

In my first attempted script I have run a=`cat file_source`, then in a do loop, tried to grep "$a" file_another.
But instead of looking for all the words in one line, the routine I've created looks for each word individually from the line it's reading.
So instead of grep "a b c" file, I got grep a file, grep b file, grep c file.
Which is great... but sometimes, I really need to know that a, b and c occurred as a phrase.

I've tried multiple ideas, from cat, to read, to while to screaming. (OK, screaming is not a function, just a reaction.)
I can get a while read routine to read the whole line of file_source, but then trying to use the line to grep for in file_target fails wonderfully, saying something to the effect of source not found or what not.

I've run the script in the directory of the file I want to look at, calling out the file, and also run it pointing to the full path/file, to no avail.

If anyone has quick suggestions, outlines, ideas, or examples, WITHOUT burning up too much of your time, I'd appreciate it.
Thank you.

Bruce