Regular_Expression.md

count the number of phone number

grep -E "[0-9]{3}-[0-9]{7}" ./test/* | wc -l

show the filename which contain the phone number

grep -lE "[0-9]{3}-[0-9]{7}" ./test/*
-E activates regular expressions (you could use egrep instead)
-l filters grep results, only the file name will be printed