[aisofteng]

More succinctly: [A-z]+[A-z0-9_-]

[kibwen]

If you look closely at your comment, you'll realize the hilarious HN bug that prevents me from writing it as you suggest. :P

[majewsky]

  [a-zA-Z][a-zA-Z0-9_-]*

FTFY

[jwilk]

[A-z] is not the same as [A-Za-z] .

The former includes a few punctuation characters that are between "Z" and "a".

[wruza]

[\]^_` included, or is that a special case?