hi friends...im a candidate for a job at cisco systems and ibm , i smoked a joint 20 days ago , does anyone know if they run hair drug tests (hair specially) as pre-hire exams?

pot can stay in your system up to 30 days

Hair samples for drug testing is VERY rare. Do yourself a favor and buy an at-home drug test for 16 bucks at any pharmacy (get the one more thc) Also, if you only smoked for one day 20 days ago, it was probably out of your system at least a week ago.