DEV Community

Dimitri Gilbert
Dimitri Gilbert

Posted on • Updated on • Originally published at

ParseArger : create bash scripts you'll want to use

So, who here writes bash scripts ? And among these scripts, some take arguments, right ?
Ok ok, so, get me any kind of documentation, usage hint or anything, like, right NOW !'s ok, we've all been there, and if you didn't, you might (not) have had a look at parsing arguments and (AND!) options in a bash's a whole kerfuffle ! Well, "NO MORE !" I say !

Meet parseArger

ParseArger is a bash program to generate standalone bash programs, at least :

  • the argument and option parsing (hey, I'm not gonna take your job !),
  • and a basic documentation (just the boring part),
  • and an install script (...),
  • and a bash completion script (...right ?),
  • and an html form (whut ..?!)
  • aaaaand a web server in bash (OH COOOOME ON !)(not really to be used apart from the time you can't do without... I'm just flexing ^^')


Oh, I know ya'll abunch of impatient nerds (at least I am...) so here is a quick run down to get going !

# download the install script
curl -s -O;
# make it executable
chmod +x get_parseArger;
# install, use --help for... help...
./get_parseArger --install;
# source bashrc, only needed once, modify according to your shell (if you don't know, it's the good one :D)
source "$HOME/.bashrc"

# generate a project
parseArger project my-awesome-project \
  --description "this is a cool project !" \
  # no commit, push or nothing, for install script generation
  --git-repo "myRandomDevName/my_awesome_project" \
  --project-subcommand my-script \
  --project-subcommand another-script

cd my-awesome-project
./my-awesome-project --help
Enter fullscreen mode Exit fullscreen mode


First things first, let's install the damn thing !
Open up a terminal and execute those commands :

# download the install script
curl -s -O;
# You are thoughtfully encouraged to spend the next few minutes reading it, just to make sure I do not have nefarious purposes, thank you.

# make it executable
chmod +x get_parseArger;
# install
./get_parseArger --install;
# source bashrc, only needed once, modify according to your shell (if you don't know, it's the good one :D)
source "$HOME/.bashrc"

# check install
parseArger --help
Enter fullscreen mode Exit fullscreen mode

More help is available on the install script, just type ./get_parseArger --help in your terminal.

Generate a script

Let's start simple with a script that has one argument, one option and one flag. We'll output the generated content to ./my-script.

parseArger generate \
  --help-message "this is a script" \
  --pos 'my-arg "my argument"' \
  --opt 'my-option "my option"' \
  --flag 'a-flag "boolean flag for my script"' \
  --output my-script
Enter fullscreen mode Exit fullscreen mode

You are now free to add your actual code at the bottom of the generated file. It will not be modified if (when !) you update the parsing code using parse.
There are more options for --pos, --opt and --flag, I'll dive deeper into that in further articles ;).
Concerning variable created, - will be replaced with _ and the variable will be prefixed with _arg_.
So --my-super-argument value is assigned to $_arg_my_super_argument

Parse a script

Now that we have a script, needs have changed and we miss some options... Let's fix that then !

# -i (or --in-place) means that we update the file with the newly generated parsing code, keeping your custom code
parseArger parse ./my-script -i \
  --opt 'missing-option "my missing option"' \
  --opt 'another-opt "yet another one"'
Enter fullscreen mode Exit fullscreen mode

Done, you you make the code that uses them :).

Completion script

The best thing about the terminal ? completion !
You can't get your mouse on the most likely button you'll need to click in a window (erf, maybe, but ...the usability...).
Well, you can in a terminal :D. Creating the scripts manually though ? Gee..., no !

parseArger completely my-script ./my-script

source ./completely.bash
Enter fullscreen mode Exit fullscreen mode

Remember you'll have to source the completion script to access completion in the terminal, you can add source /path/to/my-script/completion.bash to your .bashrc (or .zshrc and so on)

You will need completely installed for the generation to work, but once generated it's standalone.

Sometimes, things here do not work as expected and I can't figure out why, if it does for you to, use this as a workaround

# do not run completely
parseArger completely my-script \
  ./my-script \
  --no-run-completely > completely.yaml

# use the completely preview and pipe to a file...
completely preview > completely.bash
Enter fullscreen mode Exit fullscreen mode


We all have that pesky collegue that never remember how to use the oh so fantastic tools that you create (AKA you in 6 months).
Let's think about that guy a bit and throw him a bone with some documentation !

parseArger document ./my-script --out
Enter fullscreen mode Exit fullscreen mode

It's not perfect as it is just the command help in a md file, but it's a whole lot better than nothing, eh ?

Project, anyone ?

You might say that is a whole bunch of mess for a puny script, and you'd be very right !
Who says you have to stop with one script though ? I didn't.
You'd have several ways to do that but I settled on a very opinionated project structure that is as follows

├── <program>
├── <program>.rc
├── completely.bash
├── completely.yaml
├── form.html
├── Makefile
├── bin
│   ├── command-one
│   ├── command-two
│   ├── ...
└── utils
    ├── get_<program>
    ├── install
    └── webserver
Enter fullscreen mode Exit fullscreen mode

And of course I made a parseArger command for that : project

parseArger project my-bash-project
Enter fullscreen mode Exit fullscreen mode

Off the bat, it'll create the main program, an rc file for your bashrc, documentation, readme and misc stuff (makefile, installer, webserver, html form). It'll initialize a git repo in the created folder but won't add or commit anything.
With some options, it'll also create the bin folder and command scripts, configure the main program to use these commands (as for generate there'll be another article).

What belongs to Ceasar

This project was started because I couldn't find out how to modify argbash.
Most of the work was (well) done so I took the generated output and went at building a similar generator.
It is not as fancy as the original work and a bit of "grog brain developer" display ... but, meh, it works and it's miiiine.

On that subject, if you are interested in a more rounded up bash generator thingy, you might want to have a look at bashly, I use completely which is a part of it and it's awesome !

What now ?

Well, have at it ! Have fun, create awesome scripts with sh load of options !
Also as I am the only user, it's getting hard to find bugs to squash, though I am pretty sure nests can be found.
And if no bugs are to be found, maybe you have a use case I didn't think of and everyone would benefit from.
All that can be done using issues on parseArger's github repo.

Thanks for the read and I hope you found it useful (or at least entertaining :D )

See you around and happy coding !

Top comments (0)