extract() {
  for archive in "$@"; do
    if [ -f "$archive" ]; then
      case "$archive" in
        *.tar.bz2) tar xjf "$archive"    ;;
        *.tar.gz)  tar xzf "$archive"    ;;
        *.bz2)     bunzip2 "$archive"  ;;
        *.rar)     unrar x "$archive"  ;;
        *.gz)      gunzip "$archive"   ;;
        *.tar)     tar xf "$archive"     ;;
        *.tbz2)    tar xjf "$archive"    ;;
        *.tgz)     tar xzf "$archive"    ;;
        *.zip)     unzip "$archive"    ;;
        *.Z)       uncompress "$archive" ;;
        *.7z)      7z x "$archive"     ;;
        *)         echo "'$archive' cannot be extracted via extract()" ;;
      esac
    else
      echo "'$archive' is not a valid file"
    fi
  done
}