File size vs time as given by a Git repository. Inspired by http://phdcomics.com/comics/archive.php?comicid=1915.

git-size-history.sh

#!/usr/bin/env bash
# shellcheck disable=SC2214
#
# A shell script that shows the size of a file in each commit that modifies it,
# alongside the timestamp taken from the author of the commit. This is useful
# to visualize the size evolution of a file.
#
# It accepts a single option to customize its behavior, described as
# follows. The last argument must be a valid file tracked by its respective
# repository, with the first file obtained from git-ls-files(1) as default.
#
#   -C,  --directory=<path>
#           Pass the path of the desired directory to Git tools.
#
# For instance, to visualize the size breakdown of file "bar" inside directory
# "foo" in a graph, one can use the command below.
#
#   $ bash git-size-history.sh -C foo bar \
#     | gnuplot -e 'set term dumb; set xdata time; set timefmt "%s";
#                   plot "-" using 1:2 with lines notitle'
#
# Parsing of long options is adapted from https://stackoverflow.com/a/28466267.

DIR_PATH="."

while getopts C:-: OPT ; do
  if [ "$OPT" = "-" ] ; then
    OPT="${OPTARG%%=*}"
    OPTARG="${OPTARG#$OPT}"
    OPTARG="${OPTARG#=}"
  fi
  case "$OPT" in
    C | directory ) DIR_PATH="${OPTARG:-$DIR_PATH}" ;;
    ??* ) exit 1 ;;
    \? ) exit 2 ;;
  esac
done

shift $((OPTIND-1))
FILE_PATH="${1:-$(git -C "$DIR_PATH" ls-files | head -1)}"

if ! git -C "$DIR_PATH" ls-files --error-unmatch "$FILE_PATH" >/dev/null ; then
  cat <<-EOF
Usage: sh ${0##*/} [options] [file]
  -C,  --directory=<path>
EOF
  exit 1
fi

paste \
  <(git -C "$DIR_PATH" rev-list --all "$FILE_PATH" \
    | sed -e "s/$/:$FILE_PATH/g" \
    | git -C "$DIR_PATH" cat-file --batch-check) \
  <(git -C "$DIR_PATH" --no-pager log --format="%at" "$FILE_PATH") \
  | awk '{print $(NF), $(NF - 1) }'