A、grep –s -I -E、“^shell|shell$”/etc/* B、grep –s -E、“^shell|shell$”/etc/* C、grep –s -i “^shell|shell$”/etc/* D、grep -I -E、“^shell|shell$”/etc/*
A、f B、v C、i D、s E、E
A、root B、guest C、nobody D、其它