I am making a custom modpack, and I need to change the GUI button press sound for my modpack, but I don't know where the sound file is for clicking the GUI button.
Learning to better help yourself is a wonderful thing, it helps you the most! With most things programming, doing a simple Google search first is typically the best route.
Then there's the option of reading the documentation for the thing you're working on. Often they have helpful tutorials or manuals to help you. Once you find a good source for documentation, it's typically best to look there first.
Finally, you can ask a question on a forum specific to the thing you're working on (but remember to always search the forum for an answer before asking a new one!), or if your question is more general, on a site for more general development in the field you're working in.
Specifically for your question:
Sound directory (after 1.7.2)
The sound files in version 1.7.2 (specifically 13w42a) and above are scattered and hashed into different folders, which are located in:
Mac OS X: ~/Library/Application Support/minecraft/assets/objects
Copying my answer from Arqade.
How to find a sound file
In the index file, you can find a organized list of assets and some informations(hash and size) about them.
has a hash value of
b463fa47…. Remember first 2 digits(in this case
- The actual sound file is located at
.minecraft\assets\objects\<first 2 digits>\with a filename being a
<hash>without any extension. For example,
cave9.oggis located at
.minecraft\assets\objects\b4\with a filename
In your case the filename is