sequential file diff

mdiff

#!/bin/bash

if [ "$#" == "0" ]; then
	echo "diff [file1] [file2] ..."
	echo " Does diff file1 file2 ; diff file2 file3 ; diff file3 file4 ; etc"
	exit 1
fi

first="$1"
shift
while (( "$#" )); do
diff "$first" "$1"
first="$1"
shift
done

Needed for comparing monthly update files. Quickly see what changed each month. Use case was some huge NHS prescription chemical CSV files which get published every month, and only one or two lines change most months. Each pair of diff outputs shows the monthly changes.

For my data the first line in each file had the month, so it was obvious which files were being compared, stick an echo in the loop if you need to see explicitly.

I'd like to tweak this so you can pass args through to diff but some other time.