How to get difference ratio using “diff” or other command

diff()

I have two files with thousands lines. I want to get their differences ratio in lines/bytes using diff, vimdiff or other commands, even regardless of the specific differences.

Best Answer

There's a tool called diffstat that sounds like what you're looking for.

$ diff <file1> <file2> | diffstat

Example

$ diff afpuri.c afpuri1.c | diffstat
 unknown |   53 ++++++++++++++++++++---------------------------------
 1 file changed, 20 insertions(+), 33 deletions(-)

This can be used for diff output which includes multiple files in a tree as well.

References

How to get diff to report summary of new, changed and deleted lines

Related Solutions

Command-Line Diff – Handling Lines Out of Order

sort can be used to get the files into the same order so diff can compare them and identify the differences. If you have process substitution, you can use that and avoid creating new sorted files.

diff <(sort file1) <(sort file2)

Get correct number of lines in diff output

There is no newline, so wc -l is correct. Instead, you want to count the number of start of lines. One way to do it:

$ diff -y --suppress-common-lines a b | grep '^' | wc -l
1