I want to know: what is the recommended method of checking all running
services across these systems?
Since you are aware of chkconfig,service, and may be ntsysv,rcconf,
but you can check using below command which almost work in all flavor
ls -1 /etc/rc$(runlevel| cut -d" " -f2).d/S*
What is S* ?
the traditional init style makes symlinks that start with S, or K. those with S means "start", and they are run with the "start" parameter when that runlevel is entered. Those with K means "kill", those services are run with the "stop" parameter when that runlevel is entered
Full details:
ls -1 /etc/rc$(runlevel| cut -d" " -f2).d/S* | \
awk -F'[0-9][0-9]' '{print "Startup :-> " $2}'
Output:
Startup :-> bind9
Startup :-> apt-cacher-ng
Startup :-> slapd
Startup :-> cron
Startup :-> dmesg
Startup :-> inetutils-inetd
Startup :-> ssh
Startup :-> dns-clean
Startup :-> sudo
Startup :-> apache2
Startup :-> grub-common
Startup :-> ondemand
Startup :-> rc.local