Is it possible to write portable service scripts to control a daemon?

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http://unix.stackexchange.com – I (or one of my colleagues) need to write one or more shell scripts to control the execution of a daemon. We need to be able to start the daemon, tell it to gracefully shut down, and force a shutdown. Basically, it's the sort of thing one would traditionally use a script in /etc/init.d for. We will be deploying to Ubuntu. We may want to deploy to RedHat/CentOS, and possibly AIX. I'd like to have the ability to deploy to any unix, because i like doing things portably. So, is it possible to write portable service scripts? I suppose i can write a portable Bourne shell script which works like a (HowTos)