I am running a fully updated Manjaro (Arch Linux derivative) distribution with PHP 5.5.6 installed using pacman.
Some scripts I am forced to develop with are not fully compatible with PHP 5.5 yet.
Is there an easy way to downgrade to PHP 5.4 or do I have to compile it from source?
Yes it's possible to downgrade packages. Short version of possibilities:
pacman
cache of your computer if the packages are still present (/var/cache/pacman/pkg
)The procedures are explained in the wiki. The simplest one will certainly be to look in the cache, or eventually ARM if they are not present.