Scripting Plugins

What is a Lauf Plugin?

So you want to start scripting your own plugins eh? Great! Before you start hacking away though, there’s a few things you should understand. A plugin for Lauf is essentially just a normal shell script. The only difference between a normal shell script and a Lauf plugin is that Lauf passes on information to it’s plugins by using shared functions and variables.

Table 1. The list of functions and variables are the following:

Function / Variable	Name	Usage	Description
Function	yarra	yarra "Variable Name" "String"	Allows you to split a string into multiple variables. Basically a fake array or sorts.
Function	lauf_notify	lauf_notify "Heading" "Body"	Allows a plugin to notify the user information.
Variable	$lauf_exec	$lauf_exec	Holds what ever was typed into Lauf
Variable	$lauf_exec1	$lauf_exec1	Holds the command or plugin name being used
Variable	$lauf_exec2 - $lauf_exec999	everything else	The next unlimited number of variables hold anything else typed into Lauf

Open the [[Example Plugin|http://github.com/joshua-redfield/lauf/blob/testing/dev/example.sh]] and look over these instructions below.

First, let’s go over the heading comments. The best way to explain these comments is to explain to you how the core/plugins.sh works.

The 5th line of the comments is the plugin summary. This should tell the user what your plugin does. core/plugins.sh pulls this information using summ=$(head -n5 $test | tail -n1 | tr -d '#') . Head is grabbing the first 5 lines, tail grabbing just the last line of those 5 lines and tr is just removing the comment character.

The 7th line is the usage, This should tell the user the usage of your plugin(plugin arguments). core/plugin.sh pull this information using usage=$(head -n7 $test | tail -n1 | tr -d '#'). Works the same way as above.

The 9th line is the dependencies, This should tell the user what programs your script needs to function. core/plugin.sh pulls this information using depends=$(head -n9 $test | tail -n1 | tr -d '#'). Works same the same way.

Note: This means you can’t split these comments into multiple lines, they must be kept on their special line.

The next thing we’ll be covering is using the $lauf_exec1…​$lauf_exec999 variables. These variables do nothing more than hold what was typed into Lauf.

When using the shell built-in: test and [ this is also a test statement ] against the $lauf_exec1…​$lauf_exec999 vars you’ll often get an error message if the variable you are using the test statement against is a empty / unset. In order to stop this from happening you should use [[parameter expansion|https://github.com/joshua-redfield/lauf/blob/testing/dev/example.sh#L13]].

Table 2. The following list includes variables that contain useful information for plugins

Variable	Description
$lauf_app_dir	The directory where Lauf currently resides in
$lauf_app_icon	Location of where Lauf’s icon is located
$lauf_version	Version information
$lauf_app_name	Lauf’s application name
$lauf_app_motto	Lauf’s slogan
$lauf_core_dir	Location of core plugins
$lauf_plugin_dir	Location of external plugins
$lauf_app_options	General Lauf options, Allows plugins to grab information from lauf.cfg