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1、acct or psacct
acct also known as psacct (depending on if you use apt-get or yum) can monitor all commands executed by the user, including CPU time and memory usage. Once installed you can use the command sa to view statistics.
2、whowatch
Similar to acct, this tool monitors all users on the system and allows you to see in real-time the commands they are executing and the processes they are running. It outputs all processes in a tree structure so you can clearly see what's going on.
3、strace
strace is used for diagnosing, debugging, and monitoring programs calling each other. The most common way to do this is to use strace to print a list of programs called by the system, which can tell if the program was executed as expected.
4、DTrace
DTrace can be said to be the big brother of strace. It dynamically tracks and detects the instructions that the code runs in real time. It allows you to deeply analyze its performance and diagnose faults. However, it is not simple, there are as many as 1200 books on this topic.
5、Webmin
Webmin is a web-based system administration tool. It does not require manual editing of UNIX configuration files and allows you to manage the system remotely. It has a pair of monitoring modules for connecting it.
6、Stat
Stat is a built-in tool for displaying file and filesystem status information. It shows when a file was modified, accessed or changed.
7、ifconfig
ifconfig is a built-in tool for configuring network interfaces. Most network monitoring tools use ifconfig behind the scenes to put the network card in promiscuous mode to capture all packets. You can manually execute ifconfig eth0 promisc to enter promiscuous mode, and use ifconfig eth0 -promisc to return to normal mode.
8、ulimit
ulimit is a built-in tool that monitors system resources and can limit any monitored resource to not exceed the limit. For example, doing a fork ××× will not be affected at all if it is properly configured using ulimit.
9 、 CPULimit
CPULimit is a small tool used to monitor and limit the CPU usage of a process. It can be used in particular to keep the CPU usage of batch jobs within a certain range.
10 、 lshw
lshw is a small built-in tool that extracts detailed information about the hardware configuration of the machine. It can output the CPU version and motherboard configuration. w is a built-in command that displays information about currently logged in users and the processes they are running.
11、lsof
lsof is a built-in tool that lets you list all open files and network connections. From there you can see which process the file was opened by, find its specific user based on the process name, or kill all processes belonging to a user.