Compare files
1diff <file1> <file2> # -w to ignore whitespace.
2colordiff <file1> <file2> # colourised diff.
3wdiff <file1> <file2> # word diff: [โ โ] replaced word, {+ +} added word.
4vimdiff <file1> <file2> # open both files in vim (blue = entirely different lines, red = partially different).
5fgrep -f <list> <file> # compare two lists (e.g. of hosts).
Compare jar files
1diff -W200 -y <(unzip -vqq file1.jar | awk '{ if ($1 > 0) {printf("%s\t%s\n", $1, $8)}}' | sort -k2) <(unzip -vqq file2.jar | awk '{ if ($1 > 0) {printf("%s\t%s\n", $1, $8)}}' | sort -k2)