extracting uncommon part between two files

Hi,

I need to extract the uncommon (better say incremental) part from 2 files say file_1 and file_2.

file_2 contains everything that is in file_1. That is file_2 has been created internally somehow :

cat file_1 temp_file > file_2

My objective is to extract the temp_file part from file_2. Both file_1 and file_2 are available.

Any Help ?

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Thanks in advance

either diff or comm could be used to do that quite easily.

Thanks a lot!
My requirement can be achieved thru :

comm -3 file_1 file_2