Count string occurences in file - shell

Question

I am trying to count the occurence of a particular line in a file using shell script. The content of the file is:
Mon Dec 23 06:21:00 2019 [pid 3294] [ftpuser] FTP response: Client "127.0.0.1", "230 Login successfull."
Mon Dec 23 06:21:00 2019 [pid 3294] [ftpuser] FTP response: Client "127.0.0.1", "230 Login successfull."
Mon Dec 23 06:21:00 2019 [pid 3294] [ftpuser] FTP response: Client "127.0.0.1", "230 Login successfull."
Mon Dec 23 06:21:00 2019 [pid 3294] [ftpuser] FTP response: Client "127.0.0.1", "230 Login successfull."
The shell script code is:
file="vsftpd1.log"
count=0
while read str; do
echo $str
if [[ $str == *"230 Login successfull."* ]];
then
count=$((count+1))
fi
done < $file
echo $count
The output of the last line should be four. I have noticed that if condition is executing only one time. But it should run four times. Please help me to find mistake in the code, if any.
Thankxx in advance!

Answer 1

You could simplify that with grep (match occurences) and its -c (count occurences).
#!/bin/sh
file=vsftpd1.log
grep -c '230 Login successfull.' "$file"
If you need to capture the number into a variable:
count=$(grep -c '230 Login successfull.' "$file")
echo $count

Answer 2

That entire (rather inefficient) snippet of code can be replaced with the much simpler:
count=$(grep -c '230 Login successfull.' vsftpd1.log)
echo ${count}
As more explanation, grep -c returns the line count of the lines that match your search pattern. There is no need for a bash-based loop which reads one line at a time and checks the pattern - this is likely to be much faster in the grep executable.
The following transcript shows this in action:
pax:~$ grep '230 Login successfull.' qq.in
Mon Dec 23 06:21:00 2019 [pid 3294] [ftpuser] FTP response: Client "127.0.0.1", "230 Login successfull."
Mon Dec 23 06:21:00 2019 [pid 3294] [ftpuser] FTP response: Client "127.0.0.1", "230 Login successfull."
Mon Dec 23 06:21:00 2019 [pid 3294] [ftpuser] FTP response: Client "127.0.0.1", "230 Login successfull."
Mon Dec 23 06:21:00 2019 [pid 3294] [ftpuser] FTP response: Client "127.0.0.1", "230 Login successfull."
pax:~$ count=$(grep -c '230 Login successfull.' qq.in) ; echo ${count}
4