#!/bin/bash
# NAME
# color-wdiff - visualize differences between text files
# SYNOPSIS
# color-wdiff FILE0 FILE1
# DEPENDENCIES
# wdiff, reformat-html in $HOME/bin.
# DESCRIPTION
# 1. If the input files are HTML, they are reformatted, to remove
# indentation among other things.
# 2. The markup is inactivated by replacing angle brackets with the
# corresponding entities.
# 3. The files are compared with wdiff, using options which label
# insertions and deletions. The labels are HTML tags with specific
# classes.
# 4. The diff is turned into a valid HTML page by adding the required
# markup, plus CSS style for the insertion and deletion classes.
#
# The diff file is created in the directory where FILE0 resides.
# ORIGIN OF THE SCRIPT
# This script was extracted from GNUN's GNUmakefile (function
# "mark-outdated"), and adapted.
# GNUN (http://www.gnu.org/software/gnun/) is under GPLv3.
# =============================================================================
# Command-line arguments
arg=($1 $2)
set -e
close_term () {
printf '\n%s' '*** Close the terminal window or press Return.'; read OK
test -z "$OK" && exit $1
}
f[0]=$(mktemp -t cdif.XXXXXX) || close_or_exit 1
f[1]=$(mktemp -t cdif.XXXXXX) || close_or_exit 1
trap 'rm -f "${f[0]}" "${f[1]}"' EXIT
## Prepare the pages to be compared.
for n in 0 1; do
# Input a valid file.
input=${arg[$n]}
if test ! -f "$input" -o ! -s "$input"; then
echo "*** color-wdiff - Please enter file $n."; read input
input=${input%\'}; input=${input#\'}
test -f "$input" -a -s "$input" \
|| (echo 1>&2 "!!! This file doesn't exist or is empty."; close_term 1)
fi
# Name the diff after file 0.
test "$n" == "0" && diff_file=${input%.html}-diff.html
# If the file is an HTML but not a diff, process it:
if test "${input%.html}" != "$input" -a "${input%-diff.html}" == "$input";
then
# - Standardize the format for easier reading of the diff.
if test -f "$HOME/bin/reformat-html"; then
$HOME/bin/reformat-html $input ${f[$n]}
else
cp $input ${f[$n]}
fi
# - Replace chevrons with HTML entities. The page becomes simple text.
sed -i "s//\>/g" ${f[$n]}
fi
done
## Build the diff page.
# Add an HTML header to the wdiff output, with style for visualizing the
# insertions and deletions, and write the title of the page.
cat > $diff_file << EOF
${diff_file##*\/}
EOF
# Run wdiff with options to add the proper markup at the beginning and end of
# deletions and insertions.
wdiff --start-delete '' \
--end-delete '' \
--start-insert '' \
--end-insert '' \
${f[0]} ${f[1]} >> $diff_file || true
# Add the closing tags.
echo '
' >> ${diff_file}
echo -e "\n The diff file is $diff_file."
close_term 0