How to count the occurence of a string in a file, for all files in a directory and output into a new file with shell - grep

Question

I have hundreds of files in a directory that I would like to count the occurrence of a string in each file.
I would like the output to be a summary file that contains the original file name plus the count (ideally on the same line)
for example
file1 6
file2 3
file3 4
etc
Thanks for your consideration

Answer 1

CAUTION: I am pretty much an enthusiastic amateur, so take everything with a grain of salt.
Several questions for you - depending on your answers, the solution below may need some adjustments.
Are all your files in the same directory, or do you also need to look through subdirectories and sub-subdirectories, etc.? Below I make the simplest assumption - that all your files are in a single directory.
Are all your files text files? In the example below, the directory will contain text files, executable files, symbolic links, and directories; the count will only be given for text files. (What linux believe to be text files, anyway.)
There may be files that do not contain the searched-for string at all. Those are not included in the output below. Do you need to show them too, with a count of 0?
I assume by "count occurrences" you mean all of them - even if the string appears more than once on the same line. (Which is why a simple grep -c won't cut it, as that only counts lines that contain the substring, no matter how many times each.)
Do you need to include hidden files (whose name begins with a period)? In my code below I assumed you don't.
Do you care that the count appears first, and then the file name?
OK, so here goes.
[oracle#localhost test]$ ls -al
total 20
drwxr-xr-x. 3 oracle oinstall 81 Apr 3 18:42 .
drwx------. 39 oracle oinstall 4096 Apr 3 18:42 ..
-rw-r--r--. 1 oracle oinstall 40 Apr 3 17:44 aa
lrwxrwxrwx. 1 oracle oinstall 2 Apr 3 18:04 bb -> aa
drwxr-xr-x. 2 oracle oinstall 6 Apr 3 17:40 d1
-rw-r--r--. 1 oracle oinstall 38 Apr 3 17:56 f1
-rw-r--r--. 1 oracle oinstall 0 Apr 3 17:56 f2
-rwxr-xr-x. 1 oracle oinstall 123 Apr 3 18:15 zfgrep
-rw-r--r--. 1 oracle oinstall 15 Apr 3 18:42 .zz
Here's the command to count 'waca' in the text files in this directory (not recursive). I define a variable substr to hold the desired string. (Note that it could also be a regular expression, more generally - but I didn't test that so you will have to, if that's your use case.)
[oracle#localhost test]$ substr=waca
[oracle#localhost test]$ find . -maxdepth 1 -type f \
> -exec grep -osHI "$substr" {} \; | sed "s/^\.\/\(.*\):$substr$/\1/" | uniq -c
8 aa
2 f1
1 .zz
Explanation: I use find to find just the files in the current directory (excluding directories, links, and whatever other trash I may have in the directory). This will include the hidden files, and it will include binary files, not just text. In this example I find in the current directory, but you can use any path instead of . I limit the depth to 1, so the command only applies to files in the current directory - the search is not recursive. Then I pass the results to grep. -o means find all matches (even if multiple matches per line of text) and show each match on a separate line. -s is for silent mode (just in case grep thinks of printing messages), -H is to include file names (even when there is only one file matching the substring), and -I is to ignore binary files.
Then I pass this to sed so that from each row output by grep I keep just the file name, without the leading ./ and without the trailing :waca. This step may not be necessary - if you don't mind the output like this:
8 ./aa:waca
2 ./f1:waca
1 ./.zz:waca
Then I pass the output to uniq -c to get the counts.
You can then redirect the output to a file, if that's what you need. (Left as a trivial exercise - since I forgot that was part of the requirement, sorry.)

Answer 2

Thanks for the detailed answer it provides me with ideas for future projects.
In my case the files were all the same format (output from another script) and the only files in the directory.
I found the answer in another thread
grep -c -R 'xxx'