Custom variations of diff: diffh (diff history) and diffc (diff commands)

diffc-diffh.bash

#!/usr/bin/env bash

# All my gist code is licensed under the terms of the MIT license.

# Video demo: https://www.youtube.com/watch?v=nf3ddQniw-o

# diffc - diff commands
# - allows to call as: diffc 'command one' 'command two'
#   instead of:        diff  <(command one) <(command two)
#   (Just to save typing a few characters. Lol I'm a lazy programmer)
function diffc () {
  if [[ "$#" != "2" ]]; then
    echo "diffc requires two arguments"
    return 1
  fi

  local command=$(printf 'diff <( %s ) <( %s )' "$1" "$2")
  echo $command
  eval $command
}

# diffh - diff history
# - make a diff of the output of the last two commands in the shell history
function diffh () {
  # first one is 2nd to last. second is last
  # remove preceeding spaces
  local first=$(fc -ln -2 -2)
  local second=$(fc -ln -1 -1)

  # print and run diff
  local command=$(printf 'diff <( %s ) <( %s )' "${first}" "${second}")
  echo $command
  eval $command

  local error_code=$?

  # replace this 'diffh' entry in history with the command 
  history -s "$(echo $command)"
  
  return $error_code
}