Linux system learning Memo Series 3

Linux system learning Memo Series 3 This article is the third article in the series, mainly for your own memo, but also hope to help others. 3.1 Super users are actually ROOT users, which are well known in LINUX. here we just summarize that this account has several artifacts that can act as any text... information Linux system learning Memo Series 3 This article is the third article in this series, mainly for your own memo, but also hope to help others. 3.1 Super users are actually ROOT users, which are well known in LINUX. here we just summarize that this account has several artifacts that can act as the owner of any files and processes, there are also some special operations. This mainly involves the concept of file and process pig. we can use the ls-l command to check the specific attributes of the file. The UID of the ROOT account is 0, which is one of its characteristics. In short, try to avoid using this user process for daily operations. when you need the privilege, you can select the sudo command. of course, you need to configure the/etc/sudoers file so that your account can use the sudo command. 3.2 Process management we know that an important part of the operating system is process management or process scheduling. In Linux, a process has an address space and a set of data structures inside the kernel. the internal data structure records information about each process, including address space ING, the current status, priority, and network port of the process. Signal, the process is always interrupted, including human interruption, such as Ctrl + Cd, can be understood as sending a signal to the process, for example, the kill Command sends a TERM signal to the target process. of course, the signal can be ignored. if the process is quite powerful, kill-9 is required. When learning the operating system, we will involve the process status. in linux, processes are divided into Runnable, Sleeping, Zombie, Stopped, and other statuses, which are not described too much. Of course, there is also the issue of process priority, which is very simple, it is nothing more than that process can get CPU response problems more early, we can adjust their priority through the command: nice and renice. For the command to view the process, it is mainly the PS and TOP commands. the specific parameters can be queried in the manual. It should be mentioned that both PS and TOP are read in the/PROC directory, which also contains the CPU information and other machine-related content. This directory is actually the responsibility of the kernel, which throws some meaningful information into this directory.