There are two solutions available.
Detailed instructions are available in my Medium article here.
The short of it is create a special Dropbox folder and attach a folder action to this folder. Drop the remote_adjust_vol and adjust_volume scripts into the folder.
Here is the configuration for my folder action:
To run, simply start the bash shell and type sh adjust_volume [arg].
The arguments are as follows:
- mute
- unmute
- x (enter a number between -100 and 100, alters the volume by x%)
To use this, simply download the remote_volume_control file. Ensure that the Remote Apple Events option is checked under System Preferences > Sharing on the Mac who's volume you want to control.
To run, simply start the bash shell and type sh remote_volume_control [arg].
The arguments are as follows:
- mute
- unmute
- louder (increases the volume by 10%)
- quieter (decreases the volume by 10%)
- louder x (increases the volume by x%)
- quieter x (decreases the volume by x%)
The downside to this approach is that each time Apple will prompt you to enter the username and password for the computer you are connecting to.