I have installed a plugin called Vanish No Packet in a Minecraft Bukkit Server in which I play with my friend. I am the owner of the server but my friend is also op. I thought of trolling him by becoming invisible but he was able to see me. What can I do so that even the op players can't see me? What changes do I have to make in the permissions file? You can also download my server's permission file and make changes. Thanks!
Your friend can see you because all OP players have
vanish.see permission by default, so you need to negate it.
I recognized that you use PermissionsEX reading the link that you have provided, so you could add your friend to a group that negates this permission or you could add it specifically for him.
To only for him:
/pex user YourFriendNick add -vanish.see
To create a group:
/pex group aNiceGroupName add -vanish.see /pex user YourFriendNick group add aNiceGroupName
With a group you can add more friends adjusting the second command, so when you are done you can delete the group and the negative permission will be remove, allowing your friends to see vanished players again with a single command:
/pex group aNiceGroupName delete
Note: Your friend will not be able to see any vanished players if you negate the permission.
Here is an option you can use without plugins:
/effect give @s minecraft:invisibility 1000000 255 true
It does not show particles (due to the
hideParticles option being set to
true), and will apply forever (a very long time!).
To reverse this effect, you can use the following command:
/effect clear @s minecraft:invisibility