List most recently used branches, with option to check out

git-lb

#!/usr/bin/env bash
# Requires bash 4+ (not shipped with macos)

set -e
set -o pipefail


most_recent_branches() {
  git reflog show --pretty=format:'%gs ~ %gd' --date=relative \
  | grep 'checkout:' | grep -oE '[^ ]+ ~ .*' \
  | awk -F~ '!seen[$1]++'
}


get_all_branches() {
  git for-each-ref --format='%(refname:short)' refs/heads/
}


filter_non_existent_branches() {
  # Build a set of branches, calling `git` only once
  declare -lA branch_set=()
  while read -r branch; do
    branch_set["$branch"]=true
  done < <(get_all_branches)
  readonly branch_set

  while read -r line; do
    branch="$(echo "$line" | awk '{print $1}')"
    # Breaks because of ANSI codes
    if [ "${branch_set["$branch"]}" ]; then
      echo "$line"
    fi
  done
}


get_most_recent_existing_branches() {
  most_recent_branches \
    | filter_non_existent_branches
}


pretty_print_reflog() {
  awk -F' ~ HEAD@{' '{printf("  \033[33m%s: \033[37m %s\033[0m\n", substr($2, 1, length($2)-1), $1)}'
}


pick_branch() {
  pretty_print_reflog \
    | fzf \
    | awk '{print $NF}'
}


CHECKOUT=false
PICKER=false
VERBOSE=false
readonly FLAGS="chpv"

usage() {
  local exit_code="$1"
  cat <<EOF
$(basename $0) [$FLAGS]

-c    pick a branch and check it out (infers -p)
-h    print this help and exit with status 0
-p    invoke fzf to pick a branch
-v    verbose
EOF
  exit "$exit_code"
}

parse_args() {
  while getopts "$FLAGS" flag; do
    # stored in $OPTARG
    case "${flag}" in
      c) CHECKOUT=true ;;
      p) PICKER=true ;;
      v) VERBOSE=true ;;
      h) usage 0 ;;
      *)
        usage 1
        ;;
    esac
  done

  # Checkout infers picker.
  $CHECKOUT && PICKER=true

  readonly CHECKOUT
  readonly PICKER
  readonly VERBOSE
}


main() {
  parse_args "$@"
  $VERBOSE && set -x
  local chosen_branch

  # We need the output in the current shell, so run the branch refinement logic
  # in a subshell, processing the results here.
  {
    if $PICKER; then
      chosen_branch=$(pick_branch)
    else
      pretty_print_reflog
    fi
  } < <(
    get_most_recent_existing_branches
  )

  if $CHECKOUT; then
    git checkout "$chosen_branch"
  fi
}

main "$@"

I use this in two git aliases:

• git lb (git-lb)
• git sb (git-lb -p)