halt is necessary ?

[math]

Hello,

When I wants to unplugged the guru, do I have to "sudo halt" before ? or can I unplug it roughly ?

[sfzhi]

If you have disk volumes mounted read/write you always risk losing information, whether you do "sudo halt" or not. "halt" decreases the risk significantly, because it syncs the disk buffers, but there is still no guarantee that some application is not in the process of writing data at that moment. You should use the normal shutdown procedure or at least remount all volumes read-only.

[math]

> You should use the normal shutdown
And... what is the normal shutdown ? Are you talking about "shutdown -h now" ?

[birdman]

> You should use the normal shutdown
And... what is the normal shutdown ? Are you talking about "shutdown -h now" ?

Linux tries to help you with such things:
From "man halt"

       If  halt or reboot is called when the system is not in runlevel 0 or 6,
       in other words when it's running normally,  shutdown  will  be  invoked
       instead  (with  the  -h  or -r flag).

Just don't expect Solaris to be so helpful (IIRC)...

[sfzhi]

And... what is the normal shutdown ? Are you talking about "shutdown -h now" ?

Right. As birdman has pointed out, "halt" will normally call "shutdown". When writing my previous post I was thinking about "halt -f".