How i can start an php skript with a variable
i have a textfile with name sub so i have make it so but it doesn´t work:
www.domain.com/skript.php?sub=variable
[addsig]

Do it like this:

www.domain.com/script.php?textfile=NAME_OF_TEXTFILE

In your php code you can now use $textfile as a variable. [addsig]

and, if you wanna have more parameters, do it like this:
script.php?var1=test[b]&[/]ver2=test2
This will give you $var1 (with the ocntents "test"), and $var2 (with the contents "test2"). If you pass a string in there, with spaces, do it like this:
script.php?var1=Hello+You+There
This is the same as doing
$var1 = "Hello You There"
[addsig]

It's a bad idea to allow php access files at the users descression. They then have access to everything php has excess to, which in some cases, everything. Maybe make an array, with all the possible options, so they cannot choose whatever they want.