Is there a way to determine which user ran a command in bash history?

Question

We work on CentOS servers available to over a hundred employees via SSH, each with their own login. Running a normal history bash command shows all of the commands ran by all of the employees, however it does not specify which employee the command was run by. Is it possible to have history show not only the bash command that was run, but also which SSH user it was run by?

Solution

It seems like you want greater auditing on your system in general, however in relation to Bash and history, you can enable time-stamping. This in conjunction with last command and a tailored grep should help in determining which specific user executed the crime. er, command.

1. enable History timestamp.

From GNU's Bash page:

HISTTIMEFORMAT

If this variable is set and not null, its value is used as a format string for strftime to print the time stamp associated with each history entry displayed by the history builtin. If this variable is set, time stamps are written to the history file so they may be preserved across shell sessions. This uses the history comment character to distinguish timestamps from other history lines.

Reference on formatting the time string

2. Use last command

Last will show user login/logout times. This will narrow your search down to a few users.

3. grep the specific users matched above for the specific command.

something like:

grep "command" /home/{user_a,user_b}/.history

note, the history file will have additional data for the timestamp, however it will still be very readable in text.

4. create a Bash function to perform all the above

Create a function, histuser() which will take one argument: a command name, and do the above searches returning the name of the specific user. If you want this done email me. I'm easy, but not cheap.

Comments

[Spiff]

Where did you get the idea that bash's history command shows all of the commands run by all of the users on the system? It only shows the current user's history.

[tripleee]

If you have multiple persons logging into the same user account, the trivial fix is to create a personal account for each. If they need to run something with specific privileges, sudo allows for that, and also implements auditing if you want that.

[Giacomo1968]

That just shows the bash history for a user. It does not search for a command. The question is, “Is it possible to have history show not only the bash command that was run, but also which SSH user it was run by?”