What character sequence should I not allow in a filename?

Question

I found out after testing that linux allows any character in a file name except for / and null (\\0). So what sequence should I not allow in a file

Answer 1

Since you seem to be interested primarily in Linux, one thing to avoid is characters that the (typical) shell will try to interpret, for example, as a wildcard. You can create a file named "*" if you insist, but you might have some users who don't appreciate it much.