Following Linux command can be used to check two file line differences.
Before using the command you must sort the file using sort Linux command.
1.) sort err_file_1.txt > sorted_file_1.txt
2.) sdiff err_file_1.txt err_file_2.txt
Output will be shown in Linux terminal. You can write output to file using following command.
1.) sdiff err_file_1.txt err_file_2.txt >output.txt