place holder to extract information from commits
link -- https://git-scm.com/docs/pretty-formats Placeholders that expand to information extracted from the commit: %H commit hash %h abbreviated commit hash %T tree hash %t abbreviated tree hash %P parent hashes %p abbreviated parent hashes %an author name %aN author name (respecting .mailmap, see git-shortlog[1] or git-blame[1] ) %ae author email %aE author email (respecting .mailmap, see git-shortlog[1] or git-blame[1] ) %al author email local-part (the part before the @ sign) %aL author local-part (see %al ) respecting .mailmap, see git-shortlog[1] or git-blame[1] ) %ad author date (format respects --date= option) %aD author date, RFC2822 style %ar author date, relative %at author date, UNIX timestamp %ai author date, ISO 8601-like format %aI author date, strict ISO 8601 format %as author date, short format ( YYYY-MM-DD ) %ah author date, human style (like the --date=human option of git-re...