Function

Function in GRUB is very slightly different compared to POSIX shell. It doesn't require the function parenthesis ( () ) and must rely on function keyword.

Basic

Here's the an example of basic declaration:

function simple_greeting {

        echo "Hello $@"

}

grub> simple_greeting "Michelle"

Hello Michelle

grub>

Parameters

Parameters are similar of those in POSIX shell. Example:

• $@ - all parameters with positional information
• $* - all parameters without positional information
• $1, $2, $3, ... - parameter value at the specified position. $0 means nothing in this case.
• return number - return an exit code aligning to UNIX convention (0 means success)

That's all about creating function in GRUB scripting language.