I have a simple question.
When we create a file, let's say "abc.txt" and leave it blank.
The OS will show that the file is 0 bytes size and takes 0 bytes on disk.
If we save 100 of these 0 bytes file into a folder, the OS will also say that the folder's total size is 0 bytes.
This may sound logical because there is nothing in the file. But should not these files take at least a few bytes in the storage device?
After all, we save it somewhere and named it something. Shouldn't the file's name and possibly some other headers at least takes up some space?
No, they still occupy a few bytes on the file system. Otherwise I would implement a magic filesystem that stored everything encoded in the filenames on empty files.
Technically it boils down to a matter of definition though. Either the "size of a file" refers to the size of the content of the file, or it refers to the "difference" it makes in terms of free bytes on the underlying file system (that is, size of content (rounded up to the closest block- or cluster-size) + bytes used for it's inode).