Then one day, I was trying to setup MySQL on a personal Linux machine, and it wouldn't let me use my "standard password" for the admin account. I knew I could just use a different one, but I really wanted to know what the problem was. Took a long time, and I don't remember how I figured it out, but I eventually tracked it to the password ending with '!!'.
It took a while to put it together, and I never confirmed with the dns host support it's what fixed the issue but, I changed my password there, tried the transfer again, and it worked without any help from support. I suspect my plaintext password played some part in a script used in the transfer process, and was outputting the previous command in place of the !! I wish I had asked them if that was it, but if it was, they would have to admit to having my plain text password, or lie about it.
and i only use sudo to open a root shell. never to run anything directly. i don't want normal and root commands mixed in the same history.
i could keep sudo commands out of the history, but then i don't have any history for stuff done as root.
with tmux i can switch terminals easily, so i am also not tempted to run things as root that i shouldn't despite having a root shell open.
shopt -s histverify
shopt -s histreedit
i dont know why they are not the default.
On bash, you can achieve this by setting HISTCONTROL=ignorespace but that's not the default.