These are different "runlevels", which determine what daemons and processes are running. Runlevel 1 is single-user mode, meaning very few daemons are running. Runlevel S is used for the basic scripts that need to run to enter runlevel 1.
In traditional System V init systems, that'd be runlevel 1 or "single user mode." This should only be used in emergencies where normal boot is not working at all. As Linux is generally going over to systemd, the idea of a "runlevel" is going away, and instead systemd will try to hit specific "targets" during boot. You can change the run target to something like single user mode, but only if necessary.
yes windows is a multiuser OS
This is largely dependent on what "init" is being used. Generally they all will recognize the number "1" apppended on the kernel command line to mean "rescue mode" or, more accurately, "single user mode." Some inits simply use 1 as a mapping for the actual runlevel involved.
The exact meaning of this question is unclear. Most Linux systems may be shutdown in a variety of ways from the local console or a remote shell login via SSH or telnet for example. If logged in as root at a command line interface (CLI), the following commands will likely change the runlevel of most Linux systems. For a system halt, type "init 0", for a system reboot, type "init 6", for a system halt, you may also type "halt", for a system reboot, you may also type "reboot", to exit multi-user mode and enter single user mode, type "init 1" and to return to multi-user mode, try typing "init 3" and so on... Invoking the "init" command allows you to change the runlevel 'on the fly' without first executing a full shutdown of the system. If the runlevel is changed from a remote connection however, be advised that your connection will be lost if the network interfaces are shut down as a result of the runlevel change. [JMH]
Do you mean a change between GUI and console mode, then try the following, Press Ctrl+F1 to switch from GUI mode to console mode. F1 to F6 are console modes and use Ctrl+F7 to switch back to the GUI mode. Or if you mean, about changing the default mode (booting) from GUI to Console then try this, go to /etc/inittab file. change the runlevel id: to 3 for booting in Full-User mode.
yes. windows nt is a multiuser operating system
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A multiuser database may exist on a single machine, such as a mainframe or other powerful computer, or it may be distributed and exist on multiple computers. Multiuser databases are accessible from multiple computers simultaneously.
Yes.
No
Yes, a multiuser operating system is also described as a network operating system.