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.


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

$ diff <file1> <file2> | diffstat


$ 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.



My math might be a bit off, but I beleive you asked for a ratio, and I beleive this produces a ratio.

#!/usr/bin/env bash
# File 1 contains 1,2,3,4,5 on new lines
# File 2 contains 1,2,3,4,5,6,7,8,9,10 on new lines.

# Compare differentials side-by-side
diff -y 1 2 > diff

# Print lines to file which do not contain ">" prefix.
sed 's/[ ]/d' diff > MATCHES

# Print lines to file which do contain ">" prefix.
sed '/[>]/!d' diff > DIFFS

# Count lines in file that contains MATCHES between Versions of Files 1,2.
MATCHES=`wc -l MATCHES | sed 's/[^0-9]*//g'`

# Count lines in file that DID NOT MATCH between Version of Files 1,2.
DIFFS=`wc -l DIFFS | sed 's/[^0-9]*//g'`

# Sed here is stripping all but the number of lines in file.

RATIO=`echo "$MATCHES / $DIFFS" | bc -l `

# To get the ratio, we are echoing the #of_matches and the #of_diffs to
# the bc -l command which will give us a float, if we need it.
echo "You've got:" $RATIO "differential."

# Bytes...
# stat -c%s prints bytes to variable
DIFFS=`stat -c%s DIFFS`

RATIO_BYTE=`echo "$MATCHES / $DIFFS" | bc -l `
echo "Let Ratio in Bytes be" $RATIO_BYTE
# Again, we divide the matches by the diffs to reach the "ratio" of
# differences between the files.
  • The accepted answer is good enough for ratio computing. Thanks anyway! – Nathaniel Ding Oct 6 '14 at 4:07
  • 2
    $> diffstat is definitely the shell utility for this. – Tyler Maginnis Oct 6 '14 at 4:08

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