-bash: ./configure: Permission denied

[vol]

Hello,
I try to update php 4 to version 5.. but I got a problem: I'm not even able to execute ./configure. I'm on a dedicated centos 4 server, logged in as root. The configure file itself is executable. "su -" command doesn't work either... I really don't know what to do.
when using the sh ./configure command I get "./configure: line 2485: ./build/shtool: Permission denied" and "configure: error: xml2-config not found. Please check your libxml2 installation"... the rest looks ok.
I really have no idea what's wrong.

 

[SeLLeRoNe]

if you using directadmin you should use custombuild for upgrade your php version to 5

su
cd /sur/local/directadmin/custombuild/
./build clean
./build update
./build php

for select which version of php install you have to modify option.conf in /sur/local/directadmin/custombuild/ directory