Linux Learning Note--top Command (command to monitor the status of Linux systems)

The top command is a common performance analysis tool under Linux that shows the resource usage of each process in real time, such as CPU, memory usage, and so on, similar to the Task Manager of Windows.

1. Command format:

top[选项]

2. Common options:

"top -c"         显示完整的命令行而不只是显示命令名。"top -d"         指定每两次屏幕信息刷新之间的时间间隔。"top -n 3"       指定循环的次数为3次。"top -u 用户名"  指定用户名。"top -p 进程号"  指定进程号。

3. Display Information Analysis:

1) The first line of information content analysis

content	Description
11:37:29	Current system time
Up 149 days, 23:47	The system has been running continuously for 149 days, 23 hours, 47 minutes.
1 user	There are currently 1 users logged into the system
Load average:0.00, 0.00, 0.00	The three numbers behind the load average are 1-minute, 5-minute, and 15-minute loads, respectively.

2) Second line of information content analysis

content	Description
tasks:193 Total	Total number of processes
1 Running	Number of processes that are running
192 Sleeping	Number of processes for sleep
0 stopped	Number of processes stopped
0 Zombie	Number of zombie processes

3) Third line of information content analysis

content	Description
Cpu (s): 0.1%us	Percentage of CPU occupied by user space
0.1%sy	Percentage of CPU consumed by kernel space
0.0%ni	CPU percentage of processes that have changed priority in user process space
99.8%id	Percentage of idle CPU
0.0%wa	Percentage of CPU time waiting for input and output
0.0%hi	The total amount of time the CPU spends on hardware terminals
0.0%si	The total amount of time the CPU spends on software terminals
0.0%st	Steal time

4) The fourth line of information content analysis

content	Description
mem:8062100k Total	Total Physical Memory
4158524k used	Total amount of physical memory used
3903576k Free	Total Free Memory
339492k buffers	Amount of memory to use as the kernel cache

5) The fifth line of information content analysis

content	Description
swap:8191992k Total	Total Swap Area
0k used	Total number of swap areas used
8191992k Free	Total Free Swap Area
1964908k Cached	Total Buffer Swap Area

6) Analysis of the information content of the six lines

content	Description
Pid	Process ID
USER	User name of the process owner
PR	Priority level
NI	A nice value negative indicates a high priority, positive values indicate low priority
VIRT	Total amount of virtual memory used by the process, Unit kb,virt=swap+res
Res	The amount of physical memory not swapped out by the process, Unit Kb,res=code+data
Shr	Shared memory size, in kilobytes
S	Process Status: d= non-disruptive sleep state, r= run, s= sleep, t= track/Stop, z= zombie process
%cpu	CPU time consumption percentage last updated to current
%MEM	Percentage of physical memory used by the process
time+	Total CPU time used by the process, Unit 1/100 sec
COMMAND	Command name/command line

Linux Learning Note--top Command (command to monitor the status of Linux systems)