UNIX for Dummies Questions & Answers

What's the best way to see if a common name exists in two separate files?

Grep can accept multiple filenames as arguments. Suppose you're looking in file1, file2 and file3 for the name treesloth. You can simply do:

Code:

grep treesloth file1 file2 file3

The system should assume, unless you use switches to modify it, that the first argument is the regular expression you're looking for, and all additional arguments are files to search in.

Thanks, hey! I've been to Orem, Utah. There is a Thai restaurant there that is absolutely great!

Anyway, back to my question. I need a script that can find names in multiple files but I don't know the name up front. I just want to know

if name

exists in file1 AND in file 2

then

echo "name"

I know I could use grep if I knew the name in advance, but I don't.

Thanks for the help.

I'm not completely sure what you mean when you say that you "don't know the name up front". Do you mean that you just don't happen to know right now what you'll be searching for, but when the time comes you'll have a definite search term? If so, you could do something like:

Code:

foreach term ( searchterm1 searchterm2 searchterm3 )
echo -n $term "  " ; grep -l $term file1 file2 file3 | wc -l
end

That will show, for each search term, how many different files it appears in. Alternately, this:

Code:

foreach term ( searchterm1 searchterm2 searchterm3 )
echo -n $term "  " ; grep -l $term file1 file2 file3 | tr '\n' ' ' ; echo " "
end

However, I suspect that this comes closest to what you need:

Code:

foreach term ( searchterm1 searchterm2 searchterm3 )
set filecount = `grep -l $term file1 file2 file3 | wc -l`
if ( $filecount > 1 ) then
echo $term $filecount
endif
end

That will give you the search term, followed by the number of files it appears in, so long as that number is 2 or more. You can make it just show the search term by removing the "$filecount" from the 4th line. That sounds close to what you describe. If not, let us know and I'm sure we can whip it into shape.

Oh, this is all in CSH.

Sadly, I haven't had a chance to check out the Thai food around here yet. It's on the list, but if you recall the name, I'll bump it to the top. Have fun.