Engineering and technology

Run-levels in Ubuntu 16.04 LTS

Jovan Stosic March 31, 2019

Ubuntu 16.04 has moved from using init to systemd. Thus, the  concept of run-levels is replaced by the term targets.  The advantages over choosing systemd is discussed in the article The Story Behind ‘init’ and ‘systemd’: Why ‘init’ Needed to be Replaced with ‘systemd’ in Linux . The seven run-levels of init can be mapped with the targets as:

 

Run-levels Targets
0 poweroff.target
1 rescue.target
2,3,4 multi-user.target
5 graphical.target
6 reboot.target

To change the run-level non-GUI:

Source: Run-levels in Ubuntu 16.04 LTS – CodeChunk

User space

Jovan Stosic March 31, 2019

A modern computer operating system usually segregates virtual memory into kernel space and user space. Primarily, this separation serves to provide memory protection and hardware protection from malicious or errant software behaviour.

Kernel space is strictly reserved for running a privileged operating system kernel, kernel extensions, and most device drivers. In contrast, user space is the memory area where application software and some drivers execute.

Source: User space – Wikipedia