Update building-php-linux.md

Author: S. M. AMRAN

building-php-linux.md

@@ -1,5 +1,6 @@
 ### Build PHP From Source [Linux]
 ```
+#!/bin/bash
 sudo apt update && \
 sudo apt dist-upgrade && \
 sudo apt install build-essential autoconf libtool bison re2c pkg-config libxml2-dev libssl-dev && \