git-reset-files-to-branch

#!/bin/bash

usage() {
  echo "Usage: `basename "$0"` [ options ] <branch>

  Options:
    -d git_dir      git directory
"

  exit 1
}

error() {
  local msg="$1"

  echo "Error: $msg" 1>&2

  exit 1
}

[ $# -eq 0 ] && usage

getopt_flags='d:'
while getopts $getopt_flags OPTNAME; do
  case "$OPTNAME" in
    d)
      git_dir="$OPTARG"
      if [ ! -e "$git_dir" ]; then
        error "path '$git_dir' doesn't exist"
      elif [ ! -d "$git_dir" ]; then
        error "path '$git_dir' is not a directory"
      fi
      ;;
    *)
      usage
      ;;
  esac
done
shift $(( $OPTIND - 1 ))

branch="$1"
if [ -z "$branch" ]; then
  error "missing branch argument"
fi

if ! cd "$git_dir"; then
  error "unable to enter into '$git_dir'"
fi

if ! git checkout -f; then
  error "unable to: git checkout -f"
fi

if ! git pull origin "$branch"; then
  error "failed while: git pull origin '$branch'"
fi