While deleting all files beginning with the letter a there was still the file Access.txt left. Assuming that it had the correct ownership, why was it not deleted?

File extensions have no special significance in Linux for basic file operations like 'rm' - the extension does not require different syntax or flags to delete a file.

The '-R' or '-r' flag for 'rm' is used for recursive deletion of directories and their contents, not for matching files with different cases or extensions in a flat directory.

Unlike Windows, Linux does not lock files from deletion simply because they are open by another application - open files can still be unlinked from the directory while the process holds the file descriptor.

Hidden files in Linux begin with a dot (e.g., '.Access.txt') - 'Access.txt' does not start with a dot and is therefore not hidden.

Linux (and Unix-like) filesystems treat uppercase and lowercase letters as distinct characters in file names, so the glob pattern 'a*' only matches files whose names begin with the lowercase letter 'a', leaving 'Access.txt' (which begins with uppercase 'A') unaffected.