How to Get a Resumed (Counter) Output Using diff

To get a resumed (counter) output when using the diff command in the command line, you can use the following options and techniques:

1. Basic ``diff`` Output

   diff a b
   

2. Side-by-Side Output with Suppressed Common Lines

   diff -y --suppress-common-lines a b
   

3. Brief Output (Shows Only Whether Files Differ)

   diff --brief a b
   

4. Count the Number of Differences To count the number of differences, pipe the output of diff to wc -l:

   diff a b | wc -l
   

5. Summarized Output with Counts For a detailed summary, use a combination of diff and awk to count additions, deletions, and changes:

   diff a b | awk '/^</ {a++} /^>/ {d++} END {print "Additions:", a, "Deletions:", d}'
   

Example

Suppose you have two files a and b:

File a:

line1
line2
line3

File b:

line1
line2
line4

Running:

diff a b

Output:

3c3
< line3
---
> line4

To count the number of differences:

diff a b | wc -l

Output:

2

To get a summarized output:

diff a b | awk '/^</ {a++} /^>/ {d++} END {print "Additions:", a, "Deletions:", d}'

Output:

Additions: 1 Deletions: 1

This will give you a count of the number of lines that are different between the two files.