a.txt:
1;john;125;3
1;tom;56;2
2;jack;10;5
b.txt:
1;john;125;3
1;tom;58;2
2;jack;10;5
Use comm:
comm -13 a.txt b.txt
1;tom;58;2
The command line options to comm
are pretty straight-forward:
-1 suppress column 1 (lines unique to FILE1)
-2 suppress column 2 (lines unique to FILE2)
-3 suppress column 3 (lines that appear in both files)