Change the Run level with out rebooting in linux.

To view the current run level below commands are used.

[root@baby ~]# runlevel
N 3

To also view the last run level

 [root@tester ~]# who -r
         run-level 3  2010-08-09 00:16                   last=S


To change the run level with out rebooting and making it as default run level is done with the telinit command.

Change the run level in the configuration file /etc/inittab - id:3:initdefault:

switch to single usermode by 

telinit S

run level 5 

telinit 5

change in to the default runlevel 

telinit q

  telinit can also tell init how long it should wait between sending pro-

cesses the SIGTERM and SIGKILL signals.  The default is 5 seconds,  but 

this can be changed with the -t sec option.