A bash script to run a command against different branches or commits automatically

branch-compare.sh

#!/bin/bash

# Usage:
# ./compare-branches.sh "./some-command arg-1 arg-2" branch-1 branch-2
#
# https://twitter.com/elliotthilaire/status/1083859808086720512
# Thanks to @schneems, @tosbourn, and @matthewrudy for their input.

current_branch=$(git symbolic-ref --short HEAD)

command=$1
commits=${@:2}

echo "running $command on $commits"
echo "----------------------------------------"

for commit in $commits
do
  $(git checkout $commit)
  eval $command
  echo "----------------------------------------"
done

$(git checkout $current_branch)