Need help to find total counts in a string

Shell Programming and Scripting
1

Suppose I have a string " 1 A B C D F 3 F G 3 1 D L D ".

Please let me know the command which tells the above string having 3 Ds.

echo $str | grep -c "D"

It returns only 1 I know the reason but I am looking some command which should give 3.

Actually I have a file, which I need to read and store the total numbers of ":" in each record.

Any help is highly appreciated.

2 
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}
3

Try

echo " 1 A B C D F 3 F G 3 1 D L D " | tr -cd "D"| wc -c
4 
echo " 1 A B C D F 3 F G 3 1 D L D " | tr -cd "D"| wc -c

Worked perfectly...

grep -o won't work in HP Unix...Sorry I forgot to mention the Unix flavor...

Again thanks for all your help !

---------- Post updated at 07:12 AM ---------- Previous update was at 07:04 AM ----------

But could you please explain the meaning of the command...

I tried to understand (man tr) but didn't get it.

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

It returns nothing....please explain, if possible.

5

-d deletes characters which match the specified set, -c modifies it to use the complement of the set instead (anything which isn't D).

6 
akshay@nio:~$ echo " 1 A B C D F 3 F G 3 1 D L D " | awk '{print gsub(search,"&")}' search='D'
3