Question

The question is maybe trivial but I can’t get it to work. I just want to merge 2 particular files present in multiple specific folders into a new single file again in each specific folder.

cat */folder_*/*/file.a */folder_*/*/file.b > */folder_*/*/file.c

but it does not work ’cause

-bash: */folder_*/*/file.c: No such file or directory

So I thought maybe for some reason cat can’t create files (though it does), so I tried

touch */folder_*/*/file.c; cat */folder_*/*/file.a */folder_*/*/file.b > */folder_*/*/file.c

but again it does not work with cat or even touch.

Answer 1

for dir in */folder_*/*; do 
  [[ -d "$dir" ]] && ( cd "$dir" && cat file.a file.b > file.c )
done

I run the cd && cat in a subshell so you don’t have to cd back to where you started.