I have tested your modified command sequence. See below:
cd /etc/init.d
vi helloworld.sh
ls
banner.sh functions inetd.busybox rc sendsigs syslog.sysklogd
bootlogd functions.initscripts modutils.sh rcS single udev
bootmisc.sh functions.lsbinitscripts mountall.sh read-only-rootfs-hook.sh sshd udev-cache
busybox-cron halt mountnfs.sh reboot stop-bootlogd umountfs
checkroot.sh helloworld.sh netperf rmnologin.sh sysfs.sh umountnfs.sh
devpts.sh hostname.sh networking run-postinsts syslog urandom
dmesg.sh hwclock.sh populate-volatile.sh save-rtc.sh syslog.busybox xinetd
/etc/init.d# chmod +x helloworld.sh
./helloworld.sh
echo Hello from user!!!echo
cd /etc/rc5.d
ln -s /etc/init.d/helloworld.sh S99helloworld
ls
S01networking S15mountnfs.sh S20netperf S20xinetd S99rmnologin.sh
S09sshd S20hwclock.sh S20syslog S99helloworld S99stop-bootlogd
./S99helloworld
echo Hello from user!!!echo
Check also your root file system.
Are there S99helloworld and helloworld.sh files after reboot.
Have a great day,
Pavel Chubakov
-----------------------------------------------------------------------------------------------------------------------
Note: If this post answers your question, please click the Correct Answer button. Thank you!
-----------------------------------------------------------------------------------------------------------------------