Sub is a model for setting up shell programs that use subcommands, like git or rbenv using bash. Making a sub does not require you to write shell scripts in bash, you can write subcommands in any scripting language you prefer. Seems basher has the same layout, and can be consider a example of sub.

A sub program is run at the command line using this style:

$ <the-cmd> [subcommand] [(args)]

Here's some quick examples:

$ mycmd1                       # prints out usage and subcommands
$ mycmd1 version               # runs the "versions" subcommand
$ mycmd1 checkout 1.9.3-p194   # runs the "shell" subcommand, passing "1.9.3-p194" as an argument

The original sub is a command template, before your cp, please don't work on the original sub directly, we can create our cmd-subcmd group from this template like:

    # Assume create a cmd group `mycmd1`
    $ cp -fr sub sub-mycmd1     ### The new dir name is up to you
    $ cd sub-mycmd1
    $ ./prepare.sh mycmd1       ### MUST assign the new name `mycmd1`
    #    rm -fr .git
    $ ./bin/mycmd1 init         ### Add to PATH depend on the real shell env

Each subcommand maps to a separate, standalone executable program. Sub programs are laid out like so:

.
├── bin               # contains the main executable for your program
    -compleat         # https://github.com/mbrubeck/compleat
    -getoptions       # https://github.com/ko1nksm/getoptions
├── completions       # (optional) bash/zsh completions
├── libexec           # where the subcommand executables are
└── share             # static data storage
    -lib
    ---bashful        # https://github.com/jmcantrell/bashful
    ---bsda2          # https://github.com/lonkamikaze/bsda2/blob/master/ref/type.md

Each subcommand executable does not necessarily need to be in bash. It can be any program, shell script, or even a symlink. It just needs to run.

Here's an example of adding a new subcommand. Let's say your sub is named mycmd1. Run:

touch libexec/mycmd1-who
chmod a+x libexec/mycmd1-who

Now open up your editor, and dump in:

#!/usr/bin/env bash
set -e

who

Of course, this is a simple example... but now mycmd1 who should work!

$ mycmd1 who
qrush     console  Sep 14 17:15 

You can run any executable in the libexec directly, as long as it follows the NAME-SUBCOMMAND convention. Try out a Ruby script or your favorite language!

    ### --Auto completions:
      sudo ln -s $PWD/autolib/application/compleat /usr/local/bin/compleat
      echo '"\\t": menu-complete' >> ~/.inputrc
      echo '"\\e[Z": menu-complete-backward' >> ~/.inputrc
      ln -s $PWD/vol/conf/compleat.d/ ~/.compleat.d
      echo "source $PWD/vol/conf/compleat_setup" >> $SHELLRC

You get a few commands that come with your sub:

• commands: Prints out every subcommand available.
• completions: Helps kick off subcommand autocompletion.
• help: Document how to use each subcommand.
• init: Shows how to load your sub with autocompletions, based on your shell.
• shell: Helps with calling subcommands that might be named the same as builtin/executables.

If you ever need to reference files inside of your sub's installation, say to access a file in the share directory, your sub exposes the directory path in the environment, based on your sub name. For a sub named mycmd1, the variable name will be _MYCMD1_ROOT.

Here's an example subcommand you could drop into your libexec directory to show this in action: (make sure to correct the name!)

#!/usr/bin/env bash
set -e

echo $_RUSH_ROOT

You can also use this environment variable to call other commands inside of your libexec directly. Composition of this type very much encourages reuse of small scripts, and keeps scripts doing one thing simply.

Each subcommand can opt into self-documentation, which allows the subcommand to provide information when sub and sub help [SUBCOMMAND] is run.

This is all done by adding a few magic comments. Here's an example from mycmd1 who (also see sub commands for another example):

#!/usr/bin/env bash
# Usage: sub who
# Summary: Check who's logged in
# Help: This will print out when you run `sub help who`.
# You can have multiple lines even!
#
#    Show off an example indented
#
# And maybe start off another one?

set -e

who

Now, when you run sub, the "Summary" magic comment will now show up:

usage: sub <command> [<args>]

Some useful sub commands are:
   commands               List all sub commands
   who                    Check who's logged in

And running sub help who will show the "Usage" magic comment, and then the "Help" comment block:

Usage: sub who

This will print out when you run `sub help who`.
You can have multiple lines even!

   Show off an example indented

And maybe start off another one?

That's not all you get by convention with sub...

Your sub loves autocompletion. It's the mustard, mayo, or whatever topping you'd like that day for your commands. Just like real toppings, you have to opt into them! Sub provides two kinds of autocompletion:

1. Automatic autocompletion to find subcommands (What can this sub do?)
2. Opt-in autocompletion of potential arguments for your subcommands (What can this subcommand do?)

Opting into autocompletion of subcommands requires that you add a magic comment of (make sure to replace with your sub's name!):

# Provide YOUR_SUB_NAME completions

and then your script must support parsing of a flag: --complete. Here's an example from rbenv, namely rbenv whence:

#!/usr/bin/env bash
set -e
[ -n "$RBENV_DEBUG" ] && set -x

# Provide rbenv completions
if [ "$1" = "--complete" ]; then
  echo --path
  exec rbenv shims --short
fi

# lots more bash...

Passing the --complete flag to this subcommand short circuits the real command, and then runs another subcommand instead. The output from your subcommand's --complete run is sent to your shell's autocompletion handler for you, and you don't ever have to once worry about how any of that works!

Run the init subcommand after you've prepared your sub to get your sub loading automatically in your shell.

Creating shortcuts for commands is easy, just symlink the shorter version you'd like to run inside of your libexec directory.

Let's say we want to shorten up our mycmd1 who to mycmd1 w. Just make a symlink!

cd libexec
ln -s mycmd1-who mycmd1-w

Now, mycmd1 w should run libexec/mycmd1-who, and save you mere milliseconds of typing every day!

Clone this repo:

git clone [email protected]:qrush/sub.git [name of your sub]
cd [name of your sub]
./prepare.sh [name of your sub]

The prepare script will run you through the steps for making your own sub. Also, don't call it sub, by the way! Give it a better name.

So you've prepared your own sub, now how do you use it? Here's one way you could install your sub in your $HOME directory:

cd
git clone [YOUR GIT HOST URL]/sub.git .sub

For bash users:

echo 'eval "$($HOME/.sub/bin/sub init -)"' >> ~/.bash_profile
exec bash

For zsh users:

echo 'eval "$($HOME/.sub/bin/sub init -)"' >> ~/.zshenv
source ~/.zshenv

You could also install your sub in a different directory, say /usr/local. This is just one way you could provide a way to install your sub.

MIT. See LICENSE.