Table of contents
1. System status query
1. 1.uname command
root@uos~#: uname root@uos~#: uname -r
4.19 is the kernel, 0-6-amd64 is the architecture.
root@uos~#: uname -a
The name of the eagle operating system, including the time, can be displayed.
root@uos~#: cat /proc/cpuinfo
Also view CPU information
root@uos~#: cat /proc/meminfo
This is to check the memory, but there is also a simpler free command
root@uos~#: free
Mem refers to the physical memory; Swap refers to the swap partition, which is equivalent to drawing out a piece on the hard disk. When the physical memory is not enough, this partition memory will be called here, but it is best not to use it. Cause computer performance to be damaged, unless the physical memory is too small.
1.2. last command
root@uos~#: last root@uos~#: lastlog
The last command is used to check the login status of the system
lastlog is used to check all users
1.3. top command
root@uos~#: top
The display under the top command shows that it is being recorded in real time.
Load average performance load, within one minute, within five minutes and within fifteen minutes of the load.
182 total means that there are 182 processes, 1 running means that one is running, 181 sleeping means that 181 are sleeping and not participating in the process, stopped means stopped, and zombie means zombie (it used to be a normal process, but something went wrong later, it is not normal death, harmful to the program). If the process is killed, it will disappear from the total.
root@uos~#: pstree
Tree diagram of system processes
root@uos~#: dd if=/dev/zero of=/dev/null bs=1M count=100000000
dd is a command, if is an input file, and of is an output file, which means to dig a part from a zero device and place it in null.
Zero means 0, and null means nothing (equivalent to a black hole). count represents how many times, bs represents how much to write at a time.
2. Process management
2.1. ps command
root@uos~#: ps
ps is the command for process management view.
root@uos~#: ps aux
This command lists all process parameters. a means to list all processes, u means to arrange in order of users, and x means to list all the values.
root@uos~#: ps aux | grep ping
General process management will combine ps and grep, so that you can accurately find the process status and content you want to check. S+ means running status.
2.2. kill command
root@uos~#: kill -l
The kill command is not simply used to kill the process, SIGKILL (single process kill command) is the meaning of killing, the kill command is a status command,
The numbers above represent commands
root@uos~#: kill -19 4810
-19 means the command in the kill state, 4810 is the process, and SIGSTOP stops the 4010 process. T means stop.
After this operation, you can use top to check it, and you will find that there is a 1 stopped, indicating that one of the processes has stopped.
9) The difference between SIGKILL and 15) SIGTERM: 9 means kill, 165 means termination, 9 just ends the process directly, and 15 kills the process after considering all the circumstances. SIFTERM is more humane. So it is generally recommended to use 15)
