Bash: Counting instances of a string in text file with a loop - string

Question

I am trying to write a simple bash script in which it takes in a text file, loops through the file and tells me how many times a certain string appears in the file. I want to eventually use this for a custom log searcher (for instance, search for the words 'log in' in a particular log file, etc.), but am having some difficulty as I am relatively new to bash. I want to be able to quickly search different logs for different terms at my will and see how many times they occur. Everything works perfectly until I get down to my loops. I think that I am using grep wrong, but am unsure if that is the issue. My loop codes may seem a little strange because I have been at it for a while and have been constantly tweaking things. I have done a bunch of searching but I feel like I am the only one who has ever had this issue (hopefully not because it is incredibly simple and I just suck). Any and all help is greatly appreciated, thanks in advance everyone.
edit: I would like to account for every instance of the string and not just
one instance per line
#!/bin/bash
echo "This bash script counts the instances of a user-defined string in a file."
echo "Enter a file to search:"
read fileName
echo " "
echo $path
if [ -f "$fileName" ] || [ -d "$fileName" ]; then
echo "File Checker Complete: '$fileName' is a file."
echo " "
echo "Enter a string that you would like to count the occurances of in '$fileName'."
read stringChoice
echo " "
echo "You are looking for '$stringChoice'. Counting...."
#TRYING WITH A WHILE LOOP
count=0
cat $fileName | while read line
do
if echo $line | grep $stringChoice; then
count=$[ count + 1 ]
done
echo "Finished processing file"
#TRYING WITH A FOR LOOP
# count=0
# for i in $(cat $fileName); do
# echo $i
# if grep "$stringChoice"; then
# count=$[ $count + 1 ]
# echo $count
# fi
# done
if [ $count == 1 ] ; then
echo " "
echo "The string '$stringChoice' occurs $count time in '$fileName'."
elif [ $count > 1 ]; then
echo " "
echo "The string '$stringChoice' occurs $count times in '$fileName'."
fi
elif [ ! -f "$fileName" ]; then
echo "File does not exist, please enter the correct file name."
fi

Answer 1

To find and count all occurrences of a string, you could use grep -o which matches only the word instead of the entire line and pipe the result to wc
read string; grep -o "$string" yourfile.txt | wc -l

Answer 2

You made basic syntax error in the code. Also, the variable of count was never updating as the the while loop was being executed in a subshell and thus the updated count value was never reflecting back.
Please change your code to the following one to get desired result.
#!/bin/bash
echo "This bash script counts the instances of a user-defined string in a file."
echo "Enter a file to search:"
read fileName
echo " "
echo $path
if [ -f "$fileName" ] ; then
echo "File Checker Complete: '$fileName' is a file."
echo " "
echo "Enter a string that you would like to count the occurances of in '$fileName'."
read stringChoice
echo " "
echo "You are looking for '$stringChoice'. Counting...."
#TRYING WITH A WHILE LOOP
count=0
while read line
do
if echo $line | grep $stringChoice; then
count=`expr $count + 1`
fi
done < "$fileName"
echo "Finished processing file"
echo "The string '$stringChoice' occurs $count time in '$fileName'."
elif [ ! -f "$fileName" ]; then
echo "File does not exist, please enter the correct file name."
fi