Percentage value with GNU Diff

Question

What is a good method for using diff to show a percentage difference between two files?

Such as if a file has 100 lines and a copy has 15 lines that have been changed th

Answer 1

Something like this perhaps?

Two files, A1 and A2.

$ sdiff -B -b -s A1 A2 | wc would give you how many lines differed. wc gives total, just divide.

The -b and -B are to ignore blanks and blank lines, and -s says to suppress the common lines.