chkrootkit (Check Rootkit) is a common Unix-based program intended to help system administrators check their system for known rootkits. It is a shell script using common UNIX/Linux tools like the <a href="/wiki/Strings_(Unix)" title="Strings (Unix)">strings</a> and <a href="/wiki/Grep" title="Grep">grep</a> commands to search core system programs for signatures and for comparing a traversal of the <a href="/wiki//proc" class="mw-redirect" title="/proc">/proc</a> filesystem with the output of the <a href="/wiki/Ps_(Unix)" title="Ps (Unix)">ps</a> (process status) command to look for discrepancies.