Sometimes ? is too flexible, and you
only want to allow a few characters. For example,
you might want to abbreviate
without picking up "memo.ad", "!"memo.ae", and so forth.
You can match one of a set of particular characters by
putting them in brackets "[]" in the list you use with "ls".
matches either b or c but no other letters.
would match "memo.ab", "memo.ac", and nothing else.
Try that command in this directory: type a plain
"ls" first, and then "ls memo.a[bc]".
How many files does "ls memo.a[bc]" match?
Type "answer N" where N is the number.