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This article is about how to monitor the status of the Linux server. The editor thinks it is very practical, so I share it with you to learn. I hope you can get something after reading this article.

We deal with Linux servers every day, especially Linux engineers. In order to ensure the security and performance of the server, we often need to monitor the status of the server to ensure that the work can be carried out smoothly.

The commands introduced are not only applicable to server monitoring, but also to our daily development.

1. Watch

The watch command is used very frequently, and its basic function is to repeat an instruction at a specified frequency. With this command, we can repeatedly call some commands to monitor the server.

By default, the execution period of the watch command is 2 seconds, but we can use the-n option to specify the frequency of running. For example, if we want to execute the date command every 5 seconds, we can do this:

$watch-n 5 date

A server must be used by many people, especially the small partners of the department. For these little friends to fish in troubled waters, we can use some commands to monitor them.

We can who every 10 seconds to see who is using the server.

$watch-n 10 whoEvery 10.0s: who butterfly: Tue Jan 23 16:02:03 2019shs: 0 2019-01-23 09:45 (: 0) dory pts/0 2019-01-23 15:50 (192.168.0.5) alvin pts/1 2019-01-23 16:01 (192.168.0.15) shark pts/3 2019- 01-23 11:11 (192.168.0.27)

If we find that the system is running slowly, we can call the uptime command to see the average load of the system.

$watch uptimeEvery 2.0s: uptime butterfly: Tue Jan 23 16:25:48 201916 up 25 up 22 days, 4:38, 3 users, load average: 1.15,0.89, 1.02

Some key processes must not fail, otherwise it may affect the business, so we can repeat the number of all processes in the server.

$watch-n 5'ps-ef | wc-l'Every 5.0s: ps-ef | wc-l butterfly: Tue Jan 23 16:11:54 2019245

To know the server memory usage dynamically, you can repeat the free command.

$watch-n 5 free-mEvery 5.0s: free-m butterfly: Tue Jan 23 16:34:09 2019total used free shared buff/cache availableMem: 5959 776 3276 12 1906 4878Swap: 2047 0 2047

Of course, not only that, we can also repeatedly call a lot of commands to monitor some key parameters of the server.

2. Top

Using the top command, we can know many key parameters of the system, and they are updated dynamically. By default, top monitors the overall state of the system, and if we just want to know how someone is using, we can use the-u option to specify that person.

$top-u alvintop-16:14:33 up 2 days, 4:27, 3 users, load average: 0.00,0.01, 0.02Tasks: 199total, 1 running, 198 sleeping, 0 stopped, 0 zombie%Cpu (s): 0.0 us, 0.2 sy, 0.0 ni, 99.8 id, 0.0 wa, 0.0 hi, 0.0 si, 0.0 stMiB Mem: 5959.4 total, 3277.3 free, 776.4 used 1905.8 buff/cacheMiB Swap: 2048.0 total, 2048.0 free, 0.0 used. 4878.4 avail Mem PID USER PR NI VIRT RES SHR S% CPU% MEM TIME+ COMMAND23026 alvin 200 46340 7820 6504 S 0.0 0.1 systemd23033 alvin 00.05 systemd23033 alvin 20 0 149660 3140 72 S 0.0 0.1 MEM TIME+ COMMAND23026 alvin 00.00 (sd-pam) 23125 alvin 20 063 396 5100 4092 S 0.0 0.1 systemd23033 alvin 00.00 sshd23128 alvin 20 0 16836 5636 4284 S 0.0 0.1 0:00.03 zsh

In this result, you can see not only the number of processes running by alvin, but also the system resources (CPU, memory) consumed by each process, while you can still see the key parameters of the entire system.

3. Ac

If you want to know how long it takes each user to log on to the server, you can use the ac command. This command requires you to install the acct package (Debian) or the psacct package (RHEL, Centos).

If we want to know the sum of the time it takes for all users to log in to the server, we can run the ac command directly without any parameters.

$actotal 1261.72

If we want to know how long each user uses, we can add the-p option.

$ac-pshark 5.24alvin 5.52shs 1251.00total 1261.76

We can also see the sum of the time users spend on the server each day by adding the-d option.

$ac-d | tail-10Jan 11 total 0.05Jan 12 total 1.36Jan 13 total 16.39Jan 15 total 55.33Jan 16 total 38.02Jan 17 total 28.51Jan 19 total 48.66Jan 20 total 1.37Jan 22 total 23.48Today total 9.83

Summary

We can use many commands to monitor the running status of the system, this article mainly introduces three: the watch command allows you to repeat a command to monitor changes in some parameters, the top command can check the number of processes run by a user and the resources consumed, and the ac command can view the server time used by each user. Which command do you often use?

The above is how to monitor the status of the Linux server, the editor believes that there are some knowledge points that we may see or use in our daily work. I hope you can learn more from this article. For more details, please follow the industry information channel.

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