What does s in runlevel stand for in linux?

The s of runlevel in Linux stands for "Single user mode", which means single user mode; runlevel can be understood as the system status. You can set the system to use different services to start by setting runlevel, so that The operating environment of Linux is different. Setting it to "s" means single-user mode.

#The operating environment of this tutorial: linux7.3 system, Dell G3 computer.

What does the s of runlevel in Linux represent?

The runlevelm command is to check the running level of the current system. Speaking of run level, here I will expand on what the run level is.

Runlevel can be considered as the system status. To be more vivid, you can think of runlevel as a bit like Normal, safemode, and command prompt only in Microsoft's Windows operating system. Entering each runlevel requires starting or shutting down a corresponding series of services. These services are placed in the directory /etc/rc.d/rc?.d/ or /etc/rc? in the form of initialization scripts. d below (? represents the corresponding sequence number of runlevel).

In most linux distributions, there are usually 8 runlevels:

• 0 shutdown

• 1 single user Mode

• 2 Multi-user, no NFS

• 3 Full multi-user mode

• 4 None Use

• 5 graphical interface

• 6 Restart

• S ​​s Single user mode

Single user mode refers to a state in which only one user can access a certain resource. The SQL Server instance and separate data are in a Unix-like environment. A mode of working with superuser privileges on the system. This mode can usually be entered by giving the 1 or S parameter in the boot menu. This mode can only be entered through the boot menu when facing the host entity, thus ensuring that the super privileges are granted to super users who have access to the host. This operation is usually used to maintain hard disk partitions or change the superuser password and other maintenance that need to be performed before the disk is mounted. Libraries can be put into single-user mode.

Single user mode (English: Single user mode) is a mode with super user privileges when working on a Unix-like system. This mode can usually be entered by giving the 1 or S parameter in the boot menu. This mode can only be entered through the boot menu when facing the host entity, thus ensuring that the super privileges are granted to super users who have access to the host. This operation is usually used to maintain hard disk partitions or change the superuser password and other maintenance that need to be performed before the disk is mounted.

Most Linux systems lack runlevel 5. Most users log in to the server version and do not need to be graphical. When the server is turned on, the runlevel is 3

Example

[root@localhost ~]# runlevel
N 3

Recommended learning: Linux video tutorial

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