Story

An excerpt from the chat on my friend's server:

• Me: What is it with all these grey messages in the chat? Can you please turn down your usage of commands?
• Friend: Sorry, experiments with commands are my main activity on this server.
• Me: Well, you're cluttering up my chat with useless results of your commands, and it's becoming very distracting. Can you find a way to turn it off?
• Friend: I could /deop you, and you won't get them.
• Me: I don't want my deop reason to be because of your heavy usage of commands...
• Friend: Well, what else do you suggest?
• Me: Setting sendCommandFeedback to false.
• Friend: NO WAY! While the command outputs may not be useful to you, they're still useful to me.
• Me: What about using command blocks only? Just place one down to run your commands instead!
• Friend: Every time? Not happening.
• Me: Well, I'm out of ideas for this. Let's ask Arqade instead and see what they can come up with.

Problem

My friend uses commands on his server a lot, and being an operator on the server, it is getting annoying because every command he runs is spitting its output into my chat. I need to find a way to stop getting them, but I don't want to impede his progress.

Core question

Find a way to disable other operators from seeing your command feedback, but not yourself.

Invalid solutions:

• Using a command block every time.
• Setting the game rule sendCommandFeedback to false— this will stop players from seeing results to their own commands as well, which I don't want disabled.

Solution 1:

Use a Spigot/Sponge/Bukkit*/Paper server and plugins to do everything?

Spigot plugins usually only ever broadcast their output to the user that executes it.

Most of the default Minecraft things (and more) you'll only need Nucleus (if Sponge) or EssentialsX (everything else) and WorldEdit.

*Bukkit is now maintained by md_5.