grep --help
grep --version
cat apple.txt
grep -c "apple" apple.txt
grep -i "apPLe" apple.txt
grep -l "apple" *
grep -l "apple" abc.txt apple.txt
grep -o "Apple" apple.txt
grep -n "Apple" apple.txt
grep -v "Apple" apple.txt
grep "^Newton" apple.txt
grep "bread.$" apple.txt