linux - How to find words from one file in another file?

Question

In one text file, I have 150 words. I have another text file, which has about 100,000 lines.

How can I check for each of the words belonging to the first file whether it is in the second or not?

I thought about using grep, but I could not find out how to use it to read each of the words in the original text.

Is there any way to do this using awk? Or another solution?

I tried with this shell script, but it matches almost every line:

#!/usr/bin/env sh
cat words.txt | while read line; do  
    if grep -F "$FILENAME" text.txt
    then
        echo "Se encontró $line"
    fi
done

Another way I found is:

fgrep -w -o -f "words.txt" "text.txt"

Answer 1

You can use grep -f:

grep -Ff "first-file" "second-file"

OR else to match full words:

grep -w -Ff "first-file" "second-file"

UPDATE: As per the comments:

awk 'FNR==NR{a[$1]; next} ($1 in a){delete a[$1]; print $1}' file1 file2