Regular expression for valid filename

Question

I already gone through some question in StackOverflow regarding this but nothing helped much in my case.

I want to restrict the user to provide a filename that shoul

Answer 1

In case someone else needs to validate filenames (including Windows reserved words and such), here's a full expression: \A(?!(?:COM[0-9]|CON|LPT[0-9]|NUL|PRN|AUX|com[0-9]|con|lpt[0-9]|nul|prn|aux)|[\s\.])[^\\\/:*"?<>|]{1,254}\z

Extended expression (don't allow filenames starting with 2 dots, don't allow filenames ending in dots or whitespace):

\A(?!(?:COM[0-9]|CON|LPT[0-9]|NUL|PRN|AUX|com[0-9]|con|lpt[0-9]|nul|prn|aux)|\s|[\.]{2,})[^\\\/:*"?<>|]{1,254}(?

Edit: For the interested, here's a link to Windows file naming conventions: https://msdn.microsoft.com/en-us/library/windows/desktop/aa365247(v=vs.85).aspx