1. understand system conditions uname: Display system information hostname: Display host name last: list recent user logon lastlog: list the recent logon status of each user free: to display memory usage, you can also use vmstat to display detailed memory information top:
1. understand the system status
Uname: displays system information.
Hostname: displays the host name.
Last: list recent user logins
Lastlog: lists the recent logon status of each user.
Free: displays memory usage
You can also use vmstat to display detailed memory information.
Top: System Monitor
II. process
The system completes the work through processes.
Each process has an independent process number. the system calls the process number to schedule and manipulate the process.
The system's original process is init, and the init PID is always 1
One process can generate another process. all processes except init have parent processes.
III. query process
Query the process's command ps [option]
Ps-A or ps-e lists all processes
Ps-a displays all processes unrelated to the terminal
Ps-u lists processes of valid users
Ps-x list complete information
Ps-l displays process information in detail
Ps-f displays process information in a complete way
Pstree can be used to represent the parent-child relationship of a process in a tree-like manner.
Top is a common system monitoring tool (as mentioned earlier)