[SOLVED] How to read strings from a text file and use them in grep?

Issue

I have a file of strings that I need to search for in another file. So I've tried the following code:

#!/bin/bash

while read name; do
   #echo $name
   grep "$name" file.txt > results.txt
done < missing.txt

The echo line confirms the file is being read into the variable, but my results file is always empty. Doing the grep command on its own works, I'm obviously missing something very basic here but I have been stuck for a while and can't figure it out.

I've also tried without quotes around the variable. Can someone tell me what I'm missing? Thanks a bunch

Edit - input file was DOS format, set file format to unix and works fine now

Solution

My first guess is that you are overwriting your results.txt file in every iteration of the while loop (with the single >). If it is the case you should at least have the result for the very last line in your missing.txt file. Then I think it would suffice to do something like

#!/bin/bash
 
while read name; do
   #echo "$name"
   grep "$name" file.txt
done < missing.txt > results.txt

Answered By - lael.nasan