You have to specify the full path of command or script; you can put them into your own directory or into /etc/init.d directory. This script will be executed *after* all the other init scripts.You can put your own initialization stuff in here if you donât. want to do the full Sys V style init stuff.ust run the command ls âl /etc/rc3.d/ and you will see all script soft linked to /etc/init.d with numbers. Next time you reboot the system, you custom command or script will get executed via mystartup.sh. You can add more commands to this file or even call other shell/perl scripts from this file too.