Number of differences between 2 files


 
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# 1  
Old 09-01-2003
Network Number of differences between 2 files

Hi,

"diff" command takes two file names as arguements and gives the difference between the two.

How do I get the number of differences between two files ???
(Excluding whitespaces).
Don't ask me to count number of lines produced by "diff".

Thanks in advance,
Sharath
# 2  
Old 09-01-2003
diff file1 file2|wc -l
will give you what you want, right?
# 3  
Old 09-01-2003
Quote:
diff file1 file2|wc -l
wc -l would simply count all of the differences found in file 1 + file 2. Be sure to use either the -b or the -w flag to ignore whitespace, tabs and other characters. To get a better picture of the comparison using diff, pipe the output to grep and grep for the lines with a '<' or '>' symbol. That way, you will get lines that are different in file 1 or file 2.

If you are working with data files that can be sorted, look at using the comm command. You may also look at using cmp to do a comparison.

As always, see:

man diff
or
man cmp
or
man comm

Last edited by google; 09-01-2003 at 07:59 PM..
# 4  
Old 09-01-2003
sorry about that, read your post wrong. wc -l will not ignore whitespace.
# 5  
Old 09-03-2003
It's unclear what you mean by "number of changes". Number of changed lines? Number of changed characters? Number of changed regions?

Assuming the last of those (number of changed regions), one approach is to understand the output of diff. In Solaris diff (and most others, as I recall) the only lines that start with digits are the lines that specify the changed regions. so you can do this:
Code:
diff filea fileb | grep '^[1-9]' | wc -l

or
Code:
diff filea fileb | awk '/^[1-9]/ {i++} END {print i}'

But in either of these, you are at the mercy of diff, which may not have the same idea about what a "region" is as you do. With more modern diffs than I have at hand, e.g., gnu diff, you have a lot more options to control what diff shows as a difference region.
 
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