Terminal shell 실행가능 VS Automator shell 에러? PATH에 주목.

I have a simple Gruntfile that I want to be able to run from an icon in my OSX dock.

I have created a very simple shell script (launcher.sh) that I will save as an application so I can add it to my dock. It works great when I run it directly in my Terminal:

#!/usr/bin/env bash
$(grunt serve --open)

It also works fine with this shebang: #!/bin/bash

However when I call the shell script from an Automator workflow I get the following error:

launcher.sh: line 2: grunt: command not found

This is my Automator set up:

What am I doing wrong?

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Update

If I put this in my launcher.sh file:

#!/bin/bash
`/usr/local/bin/grunt serve --open`

I get a different error in Automator: env: node: No such file or directory

But, as before, if I run the script directly in Terminal its fine - so I think @mklement0 is right about the PATH

Update 2

launcher.sh

#!/bin/bash
grunt serve --open

Automator

PATH="/usr/local/bin:$PATH"
~/Public/Sites/launcher.sh

Now I'm still getting an error popup when I run it in Automator, but it has no details - it just says:

The action "Run Shell Script" encountered an error.

The Log panel shows a blank entry. Is there a way to get more info? A verbose mode perhaps?

Update 3

So this is weird... if I use &> ~/log it works. Without it it fails. 

But this is working, thanks @mklement0, it'll do for now

PATH="/usr/local/bin:$PATH"
cd ~/Public/Sites && ./launcher.sh &> ~/log