Q. I run a Linux webserver and down time is not an option for me. Now I I made some changes to my /etc/inittab file. How do I make those changes effective without rebooting my Debian Linux server?

A. The inittab file describes which processes are started at bootup and during normal operation (e.g. /etc/init.d/boot, /etc/init.d/rc, gettys…). Init distinguishes multiple runlevels, each of which can have its own set of processes that are started. Valid runlevels are 0-6 plus A, B, and C for ondemand entries.

telinit or init q option

You need to use /sbin/telinit command. It takes a one-character argument and signals init to perform the appropriate action. Q or q tell init to re-examine the /etc/inittab file.

To make changes to the /etc/inittab effective without a reboot, use init or telinit as follows:
# init q
OR
# telinit q