need help with reg. expressions

need to define if thestring is like /support/index.php

[semya]

I saw a tiny interesting script in DOM/JScript helping to validate html-forms on client-side, but it uses regular expressions, which i'm not much awared of. so, please, help me build a regular expression to define if a string is input like the following pattern: /support/index.php

so:
1) if it starts with /
2) consists only of letters and digits and _
3) and the last combination /____ . ___ can have 1 point...

thanks...

[andreasfriedrich]

Have a look at this excellent tutorial on Using Regular Expressions [etext.lib.virginia.edu].

Andreas

[semya]

Thanks a lot! I'm reviewing it right now, hope it'llhelp me...

but what about a hint concerning this particular regexp?

thanks