A shell command to get a progress bar while creating a tarball

tgz.sh

#!/usr/bin/env bash

function error() {
  # $1 err code
  # $2 err msg
  echo -e "error: $1: $2"
}

function tgz() {
  local longopts="help,output:,force"
  local opts="ho:f"

  local usage="
tgz -o|--output <OUTPUT_PATH> [ -f|--force ] FILE [ ... ]
  Create an archive with name OUTPUT_PATH containing FILE...

tgz -h|--help
  Print this help dialog and exit

ARGS:
  --output  | -o  path to where the file should be written, must not be a directory
  --force   | -f  overwrite any file that exists at OUTPUT_PATH
  FILES           file path or glob pattern for capturing input files

USAGE:
  tgz --output ./archive.tar.gz file-1.txt file-2.txt   # captures only file-1.txt & file-2.txt and writes the archive to
                                                        # ./archive.tar.gz, failing if a file already exists

  tgz -fo ./archive.tgz file-?.txt                      # captures files matching pattern file-?.txt (file-1.txt,
                                                        # file-2.txt, file-3.txt, etc.) and writes the archive to
                                                        # ./archive.tgz, overwriting the file if it already exists
"

  parsed=$(getopt --options "$opts" --longoptions "$longopts" --name "tgz" -- "$@")

  if [ $? -ne "0" ]; then
    echo -e "$usage"
    exit 1
  fi

  eval set -- "$parsed"

  local files=""
  local output=""
  local force="n"

  while true; do
    case $1 in
      -h|--help)
        echo "$usage"
        return 0
        ;;
      -o|--output)
        output=$2
        shift 2
        ;;
      -f|--force)
        force="y"
        shift
        ;;
      --)
        shift
        files=$@
        break
        ;;
    esac
  done

  if [ -d "$output" ]; then
    error 2 "can't overwrite a directory"
    return 2

  elif [ -f "$output" ] && ! [ "$force" == "y" ]; then
    error 3 "can't overwrite a file that already exists, use -f|--force to ignore files that already exist"
    return 3

  elif [ "$files" == "" ]; then
    error 4 "need some files to archive"
    return 4

  else
    for file in $files; do
      if ! [ -f "$file" ]; then
        error 5 "file \"$file\" doesn't exist"
        return 5
      fi
    done
  fi
  tar -zcO $files | pv -s $(du -sb $files | awk '{sum+=$1;} END{print sum}') | gzip > "$output"
  return 0
}