#!/usr/bin/osascript

on usage()
    set _usage to "Usage: adjust-volume number\n"
    set _usage to _usage & "For example:\n"
    set _usage to _usage & "  adjust-volume 2\t - increase volume by 2\n"
    set _usage to _usage & "  adjust-volume -2\t - decrease volume by 2"
    return _usage
end usage

on run argv
    if (count argv) < 1 then
        return usage()
    end if

    set currentVolume to output volume of (get volume settings)
    set volume output volume (currentVolume + (item 1 of argv))
end run