databasher

With lines.txt:

  printf '(%s)\n' "one two" "three four five"
  echo "How you doin'?"

Running:

  while read -r line; do
    eval command=($line)
    command+=("arg with spaces" "other arg")
    "${command[@]}"
  done < lines.txt

Yields

  (one two)
  (three four five)
  (arg with spaces)
  (other arg)
  How you doin'? arg with spaces other arg

Bash handles spaces just fine.

  # store the command in an array
  X=(echo "A B")
  # execute the command
  "${X[@]}"

Yields:

  A B

Meanwhile, UPS's web site has mostly gone down. Their home page now reads "Sorry! We Can’t Find That Page. Looks like the page you’re trying to find may have been moved or deleted."

The video in the linked page says that getopts only supports short options.

If you refer to my example above, you'll find that Bash's native "getopts" handles long options just fine. It accepts short option `-`, with an argument. This handles --long-options and --long-options=with-arguments.

Feel free to use your own formatting preferences.

Handling command-line arguments in Bash is easy. Bash's `getopts` handles short and long arguments gnu-style without any problem, out of the box, without any need for libraries or complicated packages.

This pattern handles lots of styles of options: short and long options (-h, --help), `--` for separating options from positional args, with GNU-style long options (--output-file=$filename).

  while getopts :o:h-: option
  do case $option in
         h ) print_help;;
         o ) output_file=$OPTARG;;
         - ) case $OPTARG in
                 help ) print_help;;
                 output-file=* ) output_file=${OPTARG##*=};;
                 * ) echo "bad option $OPTARG" >&2; exit 1;;
             esac;;
         '?' ) echo "unknown option: $OPTARG" >&2; exit 1;;
         : ) echo "option missing argument: $OPTARG" >&2; exit 1;;
         * ) echo "bad state in getopts" >&2; exit 1;;
     esac
  done
  shift $((OPTIND-1))
  (( $# > 0 )) && printf 'remaining arg: %s\n' "$@"

It turns out they are very similar to binary loadlifters in most respects.

Bash `getopts` handles short and long arguments gnu-style without any problem. The following code handles args like "-h", "-i $input-file", "-i$input-file", "--in=$input-file", and "--help":

  while getopts :i:h-: option
  do case $option in
         # accept -i $input-file, -i$input-file
         i ) input_file=$OPTARG;;
         h ) print_help;;
         - ) case $OPTARG in
                 help ) print_help;;
                 help=* ) echo "Option has unexpected argument: ${OPTARG%%=*}" >&2; exit 1;;
                 in=* ) input_file=${OPTARG##*=};;
                 in ) echo "Option missing argument: $OPTARG" >&2; exit 1;;
                 * ) echo "Bad option $OPTARG" >&2; exit 1;;
             esac;;
         '?' ) echo "Unknown option $OPTARG" >&2; exit 1;;
         : ) echo "Option missing argument: $OPTARG" >&2; exit 1;;
         * ) echo "Bad state in getopts" >&2; exit 1;;
     esac
  done
  shift $((OPTIND-1))

Thanks!

Like @bxparks, I have a template for my bash scripts command-line parsing, but I like to stick to GNU-style options and I find that Bash's getopts command handles all these cases without trouble:

command -ffilename -f filename --file=filename -- -f is not an option

My template is at https://gist.github.com/webb/ff380b0eee96dafe1c20c2a136d85ef....

It would not be difficult. Nuclear reactors could provide power almost indefinitely. Greenhouses could maintain plant life. Animals could be bred and slaughtered. A quick survey would have to be made of all the suitable mine sites in the country, but I shouldn't be surprised if several hundred thousand of our people could be accommodated. Every nation would undoubtedly follow suit.

I use GraphViz to produce a visual, browsable version of the NIEM data model. GraphViz can output images and HTML maps, which allows easy building of clickable web pages with hover notes.

See the diagram at https://niem.github.io/model/4.2/nc/ItemType/ . Hover over a term to see its definition. Click on a term to navigate to its diagram.

My go-to would be tar:

`$ tar -C $source-dir -c . | tar -C $dest-dir -x`

Why not use bash's printf %q?

   string=$(printf ' %q' "${array[@]}")

Pandoc calls these "Line blocks": https://pandoc.org/MANUAL.html#line-blocks

TCL had an amazing architecture for someone who was working in C. In C, you'd (1) create an instance of a TCL interpreter, (2) register your C functions with the TCL interpreter, and then (3) load scripts into the TCL interpreter. You'd do all your fast stuff in your C code, and just use the TCL for stitching together the high-level logic.