Hammerspoon: The Best Way of Passing Path Arguments to HS?

[roeybiran]

Hello everyone,
I’m interested in finding out if there’s an ideal way of passing paths to HS functions from other programs — LaunchBar, for example. Paths selected in LB can be passed on to LaunchBar “Actions”, which are basically scripts that accept any argument.

From thereon, I can do pretty much whatever I want, and in context of passing input to HS:

1. One option is AppleScript, with something like tell app "Hammerspoon" to execute lua code "spoon.mySpoon.myFunc(" & thePaths & …"), but I feel it's shaky and prone to AS’ idiosyncracies and escaping issues.

2. Another options is to use hs.urlevent.bind, and then run a shell script in LB, something along the lines of open -g hammerspoon://myFunc?path1=foo. However, I would like the extra work required in preparing each argument and formatting the URL, and then again it feels like a lot more can go wrong with this approach compared to simply calling an executable with space-delimited paths as arguments.

Thanks in advance!

[latenitefilms]

There's also: hs.ipc

[roeybiran]

Hi @latenitefilms,
I’ve read through the module’s docs, but still couldn’t figure out a way to pass arguments to HS from another app. Specifically, how will I be able to receive those arguments within the Lua code?

Thanks.

[latenitefilms]

You can use the hs command line tool to control Hammerspoon.

For example, if you have this function in init.lua:

function myTest()
    print("test")
end

...then trigger hs -c "myTest()" from Terminal, it will write "Test" in the Console.

[roeybiran]

Thanks for the reply — it’s a shame I haven’t even considered checking if there’s a man for the hs tool. I had no idea it has such depth.

Anyway, how do I pass parameters to the function I specify after -c? I did the following:

1. Listed some quoted, space-separated paths after the function, with or without a preceding —, for example: hs -c “myTest() '/Users/foo/bar' '/usr/local/bin’.
2. To access _cli.args or _cli._args within the Lua code, the most reasonable thing to me was to treat args (or _args) as a property of the single parameter passed to the function (i.e. myTest(_cli)), but that didn’t work.

[latenitefilms]

You can use command substitution to pass along the output of other commands as arguments.

For example, if you have this function in init.lua:

function alert(message)
    hs.alert(message)
end

You can use this Terminal command to display the date as an alert:

hs -c "alert(\"$(date)\")"

To clarify, by passing the -c argument to hs it:

Specifies a Hammerspoon command to execute. May be specified more than once and commands will be executed in the order they appear. Disables colorized output unless -N is present. Disables interactive mode unless -i is present. If -i is present or if stdin is a pipe, these commands will be executed first.

So you can essentially pass along ANY Lua code, in the similar way to how tell app "Hammerspoon" to execute lua code in AppleScript-land works.

[roeybiran]

Thanks! I think I’ll stick with urlevent. Seems safer when working with paths.

[ipatch]

You can use the hs command line tool to control Hammerspoon.

For example, if you have this function in init.lua:

function myTest()
    print("test")
end

...then trigger hs -c "myTest()" from Terminal, it will write "Test" in the Console.

i am definitely missing something here, but where do i find the hs command line tool.

I installed Hammerspoon using brew

brew cask install hammerspoon

and searching through my $PATH env var I do not see any CLI cmd called hs

Update

wow that hs bin was really buried within the app bundle, and I ended up having to load the ipc module within ~/.hammerspoon/init.lua in order to even run the most trivial _print_ function.

Is there a particular place where this is documented somewhere?

Having to sift through github issues opened / closed to find info is somewhat a PITA.

_for future me_ 👴🏻

/Applications/Hammerspoon.app/Contents/Resources/extensions/hs/ipc/bin/hs

[latenitefilms]

You can install the Command Line tool via:

hs.ipc.cliInstall()

For documentation on the tool see here.