Shell Programming and Scripting

echo "1 A B C D F 3 F G 3 1 D L D" | grep -o "D" | wc -l

echo "1 A B C D F 3 F G 3 1 D L D" | tr ' ' '\n' | grep -c "D"

x="1 A B C D F 3 F G 3 1 D L D"
y=${x//[^D]}
echo ${#y}

echo " 1 A B C D F 3 F G 3 1 D L D " | tr -cd "D"| wc -c

echo " 1 A B C D F 3 F G 3 1 D L D " | tr -cd "D"| wc -c

echo " 1 A B C D F 3 F G 3 1 D L D " | tr -cd "D"

akshay@nio:~$ echo " 1 A B C D F 3 F G 3 1 D L D " | awk '{print gsub(search,"&")}' search='D'
3