菜鸟a,b,c,h run level的简单问题

george16

a,b,c,h These are not true run levels; they differ from run levels in that the init
command cannot request the entire system to enter these run levels.

又查了一些，但是感觉还不是很清晰。

Defined run levels:
0-1: Reserved for future use
2: Multiuser mode with NFS resources shared (default run level)
3-9: Defined according to the user's preferences
m,M,s,S: Single-user mode (maintenance level)
a,b,c: Starts processes assigned to the new run levels while leaving the existing processes at the current level running
Q,q: init command to reexamine the /etc/inittab file Note: When a level from 1 to 9 is specified, the init command kills processes at the current level and restarts any processes associated with the new run level based on the /etc/inittab file.

run level除了0, 1, 2---9以外，还有a,b,c,h，我看了一下注释，又想了一下鄙公司的是2b, 2c，那a,b,c,h其实不是真的run level。查了一下资料，是如上英文所述。不是很理解，这种run level是不能通过init进入，但是2b,2c等等又有何区别呢。

cat /etc/inittab |grep tsm，是可以看到原来2b, 2c的run level


# cat /etc/inittab |grep tsm
tsmsched:2cnce:/usr/local/tsm/rc.tsmsched #Start TSM scheduler
tsmcad:2bnce:/usr/local/tsm/rc.tsmcad #Start TSM client acceptor daemon

yddll

man telinit

a,b,c,h          Tells the init command to process only those records in the /etc/inittab file with a, b, c, or h in the run level field. These four arguements, a, b, c, and h, are not true run levels. They differ from run levels in that the init command cannot request the entire system to enter run levels a, b, c, or h.

When the init command finds a record in the /etc/inittab file with a value of a, b, c, or h in the run level field, it starts the process. However, it does not kill any processes at the current run level; processes with a value of a, b, c, or h in the run level field are started in addition to the processes already running at the current system run level. Another difference between true run levels and a, b, c, or h is that processes started with a, b, c, or h are not stopped when the init command changes run levels. Three ways stop a, b, c, or h processes:

    * Type off in the Action field.
    * Delete the objects entirely.
    * Use the init command to enter maintenance state.

george16

Thanks...

mark_tj

学习了，刚接触