Question

I’m obviously missing something simply, and know the problem is that it’s creating a blank output which is why it can’t compare. However if someone could shed some light on this it would be great – I haven’t isolated it.

Ultimately, I’m trying to compare the md5sum from a list stored in a txt file, to that stored on the server. If errors, I need it to report that. Here’s the output:

root@vps [~/testinggrounds]# cat md5.txt | while read a b; do
>   md5sum "$b" | read c d
>   if [ "$a" != "$c" ] ; then
>     echo "md5 of file $b does not match"
>   fi
> done
md5 of file file1 does not match
md5 of file file2 does not match

root@vps [~/testinggrounds]# md5sum file*
2a53da1a6fbfc0bafdd96b0a2ea29515  file1
bcb35cddc47f3df844ff26e9e2167c96  file2

root@vps [~/testinggrounds]# cat md5.txt
2a53da1a6fbfc0bafdd96b0a2ea29515  file1
bcb35cddc47f3df844ff26e9e2167c96  file2

Answer 1

I’m not going to argue. I simply try to avoid double read from inside loops.

#! /bin/bash

cat md5.txt | while read sum file
do
    prev_sum=$(md5sum $file | awk '{print $1}')
    if [ "$sum" != "$prev_sum" ]
    then
        echo "md5 of file $file does not match"
    else
        echo "$file is fine"
    fi
done