Using grep with two variables

Question

I want to use grep with two variables in a shell script

var = match

cat list.txt | while read word_from_list; do
    grep "$word_from_list" "$var" >> words_found.txt
done

But grep expects to get a file as second input:

grep: match: No such file or directory

How can this be solved?

Answer 1

A quick scan of the grep man page suggests that you can use -e for multiple patterns, eg.

grep -e "$word_from_list" -e "$var"

If you find yourself with a large number of patterns, you might want to use the -f option to read these from a file instead.