empty .bash_history. Server Hacked??

hi all,
I've 5 servers with TSL 2.2 kernel 2.4.34 that i controll throught ssh
connection.
This morning,checking server's health with chkrootkit, in 1 of servers
this message appared :

"Warning: `//root/.bash_history' file size is zero"

Panic??
looking for some cause in the log file, in auth/info I've seen that in
the same time at the same day of the last modication of .bash_history
i've logout from all 5 servers.

probably,i've not use "exit" procedure but i've close the konsole (
with one tab for each server ).
Could be that server had badly completed the logout procedure? di i
have to check something else?? ideas? suggestions?

thanks a lot in advace

lore


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