"cat\ \/dev\/null\ >*sh_history" OR "cat\ \/dev\/zero\ >*sh_history" OR "chattr\ \+i*sh_history" OR "echo\ \"\"\ >*sh_history" OR "empty_bash_history" OR "export\ HISTFILESIZE=0" OR "history\ \-c" OR "history\ \-w" OR "ln\ \-sf\ \/dev\/null\ *sh_history" OR "ln\ \-sf\ \/dev\/zero\ *sh_history" OR "rm\ *sh_history" OR "shopt\ \-ou\ history" OR "shopt\ \-uo\ history" OR "shred\ *sh_history" OR "truncate\ \-s0\ *sh_history"