From a security perspective I know this is a really bad idea but I'm trying to make it so that every user on my system can recall the most recent and available command history in the entire system from every user.

For example, if I'm currently logged in as Steve and run a few commands, then switch over into Bryan, I want Bryan to be able to recall Steve's and anyone before hims command history.

So is there a way to combine or append every users .bash_history together to be universally shared?

maybe try to set up some type of linked file in a central localization that is linked to every user in the system.

not tested example:

first delete the original .bash_history file, then create a new file in that central location.
theoretically then every users commands will be sent to that file in /opt instead. as they all are soft linked to their own pseudo bash_history file then who ever uses a command will be written to the /opt/file instead with permissions to be read write for everyone.

the file can be anywhere as long as the right permissions are set to the file.

Thanks, I'll get back to you if it works or not.

yes please do. I am very curious to see if that works.

Note that bash does not write to .bash_history during the session. The .bash_history file is updated when the session closes. Having multiple users' shells writing end-of-session blocks to the same history file (and each time truncating it to HISTFILESIZE lines) will likely just make a mess.

Do you really want users "ctrl-r"-ing back through each other's commands?

Note the .bash_history has 0600 permissions, bash may check the permissions before writing. Just thinking out loud.

Let's just hope there are no passwords on your cmd lines EVER....