mjhjmtu

I need to look for the string "Total CPU time used" in a set of files that are generated in an iterative calculation within a great number of subfolders called folder_A, folder_B, folder_C and so on.

So in folder_A i would have

file_1_1
file_1_2
file_1_3
file_1_4
file_1_5
file_2_1
file_2_2
file_2_3


next to some other files with different names. In folder_B there would be

file_1_1
file_1_2
file_1_3
file_1_4
file_1_5
file_2_1
file_2_2
file_2_3
file_2_4
file_2_5
file_3_1

and so on, so every subfolder would contain a different amount of iterative steps and thus a different number appending the last file. I think the way to go is using recursive grep sorting out the alphabetically last file, the code I've tried is:

grep -r "Total CPU time used" */file_* | tail -1

However this only gives me an output of the last file in the last directory folder_Z. How do I grep the string from all subdirectories so that folder_A/file_2_3, folder_B/file_3_1 and so on are not skipped?

It's the tail -1 that gives you the last line of the result of the grep call. This likely comes from a match in the last file in the last directory.

Instead, you will need to loop over the directories. This is using bash:

for dir in folder_*/; do
 files=( "$dir"/file_* )
 grep -F 'Total CPU time used' "$files[-1]"
done

This would iterate over the directories. For each directory, the last file (in the dictionary order sense) is grepped for the string that you are searching for.

I'm using -F with grep as I'm looking for a fixed string and not a regular expression.

If you want to additionally get the filename of the file in the grep output, then either tag on /dev/null as a last argument to grep (grep will include the filename when matching across more than one file operand), or use grep with -H, if your grep supports it.