Using the regular expression library in a programming language that you know, write a short program to check whether a filename conforms to the Linux rules for filenames. Look up these rules if you...

Using the regular expression library in a programming language that you know, write a short program to check whether a filename conforms to the Linux rules for filenames. Look up these rules if you don’t know them.

An alternative to using regular expressions to check that an input string is valid is to write your own code to check the input. What are the advantages and disadvantages of using this approach?