Quick PoC script for file content comparison

gistfile1.txt

#!/bin/sh
# shellcheck shell=sh # Written to be POSIX compatible

# Created by Jacob Hrbek identified using a GPG identifier assigned to an electronic mail <kreyren@rixotstudio.cz> according to keyserver <https://keys.openpgp.org/> assuming said keyserver not hijacked

#set -e # Exit on false

###! Quick assertion wrapper
die() { printf 'FATAL: %s\n' "$2"; exit "$1" ;}

###! This is a dumb Proof-of-concept for implementation of showing a difference of two files for Sumit
###! Expects two paths to the file provided as an argument that it will try to compare
###! This is a haste implementation and should not be used in any system
compareLines() {
	firstFile="$1"
	secondFile="$2"

	# Set the counter so that $((lines+1)) works
	lines=0

	# Process each line in file supplied in the first argument
	## NOTICE: Do not use for loop to avoid pitfall https://mywiki.wooledge.org/BashPitfalls#pf1
	for lines in 1 2; do

			# Show the line that is being compared
			content="$(ex +${lines}p -scq "$firstFile")"
			compared_content="$(ex +${lines}p -scq "$secondFile")"

			# Compare the lines
			if [ "$content" != "$compared_content" ]; then
				# Output that the file is different
				cat <<-OUTPUT
					Line '$lines' is different in file '$1' comparing to the same line in file '$2'

					>>> $content
					>>> $compared_content
				OUTPUT
			elif [ "$content" = "$compared_content" ]; then
				# Output that the file is same
				cat <<-OUTPUT
					Line '$lines' is same in file '$1' comparing to the same line in file '$2'

					>>> $content
					>>> $compared_content
				OUTPUT
			else
				die 255 "Unexpected trap, DAMN YOU SUN AND YOUR COSMIC RAYS! .. or developer is incompetent"
			fi
	done
}

# Invoke
compareLines "$(pwd)/A.md" "$(pwd)/B.md"