How can I grep exact years in my file which contains world champions from years 1950-2000 but I want only years 1950/60/70/80/90/00? Thank you so much 
Multiple years grep
grep;search;file search
grep -E 19[5-9]0|2000 man grep:    -E, --extended-regexp          Interpret PATTERN as an extended regular  expression  (ERE,  see          below).