Shell Programming and Scripting

vnix$ cd /tmp
vnix$ mkdir foo bar
vnix$ echo one >foo/one
vnix$ echo one >bar/one
vnix$ echo two >foo/too
vnix$ echo three >foo/three
vnix$ echo four >bar/three
vnix$ diff -r foo bar
diff -r foo/three bar/three
1c1
< three
---
> four
Only in foo: too
vnix$

#!/bin/sh

case $# in 2);; *) echo "syntax: $0 dir1 dir2" >&2; exit 2;; esac

dir1="$1"
dir2="$2"

base1=`basename "$dir1"`
base2=`basename "$dir2"`

# note: predictable temp names are a security problem!
# FIXME: use something fancier here
# Also, won't work if dir1 or dir2 is directly in /tmp ...
mkdir /tmp/$base1 /tmp/$base2

# clean out temporary directories if interrupted
trap 'rm -rf /tmp/$base1 /tmp/$base2' 0
trap 'exit 127' 1 2 3 5 15

while read d t; do
  for f in "$d"/*; do
    test -d "$f" || continue
    egrep -v '^(HDR|FTR)' "$f" | sort >"$t"/${f#"$d"}
  done
done <<HERE
$dir1 $base1
$dir2 $base2
HERE

diff -r /tmp/$base1 /tmp/$base2 | egrep '^(Only in |diff )'