A shell script for monitoring the load of Linux system and CPU, memory, hard disk, and number of users

Use Shell scripts to monitor the load, CPU, memory, hard disk, and number of user logins in the Linux system.
　　In the past few days, I have been studying and studying shell scripts, and I have written some system load, CPU, memory, hard disk, and user count monitoring scripts. In the absence of nagios monitoring, as long as the server can access the Internet, the administrator can be reminded of the usage of system resources by sending emails.

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