Need help writing for loop shell script
 

i am trying to write a script (which I havent done since college) that will grep each line from a file named Backlist which contains the titles of about 850 ebooks against another file named HQNlist which contains about 5500 lines which are book titles plus their corresponding ISBN codes. I want to be able to find those 850 matching titles and write them to a new file because I need to make a list of those ISBNs.

I wrote this script but it just writes the entire HQNlist many times to the new file:

Any ideas?

Thanks in advance

That should basically do it; if the stuff in the first file (which ends up in the $line variable) contains anything other than "normal" characters like letters & numbers, we may need to enhance the grep a little, but this is the basic idea.

I put your code into [CODE] tags to make it easier to read.

Sasha suggested the same approach that I was going to. To see why the original approach was not working, you could try inserting an echo statement to see the value of "line" each time thru the loop.

I tried Sasha's approach. The results were just a blank file. Some of the lines have punctuation.
Is there a way to ignore special characters or should I try to remove all the punctuation from these files?

How about show us a snippet of what's inside each file; that'd be the best way we can ensure that the grepping will work when it encounters odd characters.

whats the content of Backlist ?

could be there are spaces in each line.

maybe you need to do something like: sed -n "$i"p instead.

A few lines from Backlist:
You've Got Male
The Darkest Facts: A Lords of the Underworld Companion
The Darkest Fire
The Amazon's Curse

From HQNlist:
Back on Blossom Street 9781426814686
Last Known Victim 9781426814693
The Healer 9781426814709
Rogue 9781426814716

does that sed command remove the spaces?

use grep's -f option

*delete*

Using the data you gave, I've adjusted it and find that the above now works for me. I suspect a problem with newlines and/or spaces, particular spaces, were causing troubles before.

See if that works for you?

SORRY - I initially left out the quotes around the `echo $(..)` which should be there -- please note that and correct..

ghostdog, I tried this and it didn't work. Any clue why? It'd be great if it did -- nice and simple!

Sasha, your previous code (post #2) could work, but you inadvertently embedded $line in single quotes, preventing shell expansion. ghostdog's solution works for me. Cheers!

This is weird colucix :scratch:

ghost*'s -f idea does not work for me, and neither does my initial suggestion which as you suggest should work with double-quotes (I changed the quotes and still no go).

this returned 5795 lines which is kind of strange being its a few hundred more than contained in the HQNlist

I wish grep -f worked, it was the first thing i tried last night

That's really weird. :scratch:

Here is my sample session:
and
:scratch: