Linux commands: Top command

Top is a dynamic display process where the current state can be refreshed continuously with the user key. If the command is executed in the foreground, it will monopolize the foreground until the user terminates the program. More accurately, the top command provides real-time status monitoring of the system's processor. It will display the most "sensitive" CPU in the system. Task List. This command can be used by CPU. Memory usage and execution time to sort tasks, and many of the features of the command can be set through interactive commands or in personal customization files.

Top-12:38:33 up, 23:15, 7 users, Load average:60.58, 61.14, 61.22

tasks:203 Total, running, 139 sleeping, 4 stopped, 0 zombie

Cpu (s): 27.0%us, 73.0%sy, 0.0%ni, 0.0%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st

mem:1939780k Total, 1375280k used, 564500k free, 109680k buffers

swap:4401800k Total, 497456k used, 3904344k free, 848712k cached

PID USER PR NI VIRT RES SHR S%cpu%MEM time+ COMMAND

4338 Oracle 0 627m 209m 207m R 0 11.0 297:14.76 Oracle

4267 Oracle 0 626m 144m 143m R 6 7.6 89:16.62 Oracle

3458 Oracle 0 672m 133m 124m R 0 7.1 1283:08 Oracle

3478 Oracle 0 672m 124m 115m R 0 6.6 1272:30 Oracle

3395 Oracle 0 672m 122m 113m R 0 6.5 1270:03 Oracle

3480 Oracle 0 672m 122m 109m R 8 6.4 1274:13 Oracle

3399 Oracle 0 672m 121m 110m R 0 6.4 1279:37 Oracle

4261 Oracle 0 634m 100m 99m R 0 5.3 86:13.90 Oracle

25737 Oracle 0 632m 81m 74m R 0 4.3 272:35.42 Oracle

7072 Oracle 0 626m 72m 71m R 0 3.8 6:35.68 Oracle

16073 Oracle 0 630m 68m 63m R 8 3.6 175:20.36 Oracle

16140 Oracle 0 630m 66m 60m R 0 3.5 175:13.42 Oracle

16122 Oracle 0 630m 66m 60m R 0 3.5 176:47.73 Oracle

786 Oracle 0 627m 63m 63m R 0 3.4 1:54.93 Oracle

4271 Oracle 0 627m 59m 58m R 8 3.1 86:09.64 Oracle

4273 Oracle 0 627m 57m 56m R 8 3.0 84:38.20 Oracle

22670 Oracle 0 626m 50m 49m R 0 2.7 84:55.82 Oracle

I. Top FIVE ELEMENTS statistics

The first five elements of the statistical information area are the statistical information of the whole system.

1. The first line is the task queue information

Results of execution with uptime command:

[Email protected] ~]# uptime

13:22:30 up 8 min, 4 users, Load average:0.14, 0.38, 0.25

The contents are as follows:

12:38:33	Current time
Up 50days	System run time, format last: minutes
1 user	Number of currently logged on users
Load average:0.06, 0.60, 0.48	System load, which is the average length of the task queue. The three values were 1 minutes, 5 minutes, and 15 minutes ago to the present average.

2. Second to third behavioral process and CPU information

When there are multiple CPUs, the content may be more than two lines. The contents are as follows:

tasks:29 Total	Total number of processes
1 Running	Number of processes that are running
Sleeping	Number of processes for sleep
0 stopped	Number of processes stopped
0 Zombie	Number of zombie processes
Cpu (s): 0.3% US	Percentage of CPU occupied by user space
1.0% Sy	Percentage of CPU consumed by kernel space
0.0% ni	CPU percentage of processes that have changed priority in user process space
98.7% ID	Percentage of idle CPU
0.0% WA	Percentage of CPU time waiting for input and output
0.0% hi
0.0% si

3.45th Behavior Memory information.

The contents are as follows:

MEM:191272K Total	Total Physical Memory
173656k used	Total amount of physical memory used
17616k Free	Total Free Memory
22052k buffers	Amount of memory to use as the kernel cache
SWAP:192772K Total	Total Swap Area
0k used	Total number of swap areas used
192772k Free	Total Free Swap Area
123988k Cached	The total amount of buffer swap area. The in-memory content is swapped out to the swap area and then swapped in to memory, but the used swap area has not been overwritten, which is the size of the swap area where the content already exists in memory . When the corresponding memory is swapped out again, it is no longer necessary to write to the swap area.

Two. Process information

Column Name	Meaning
Pid	Process ID
PPID	Parent Process ID
Ruser	Real User Name
Uid	User ID of the process owner
USER	User name of the process owner
GROUP	Group Name of Process owner
Tty	The terminal name of the startup process. Processes that are not started from the terminal are displayed as?
PR	Priority level
NI	Nice value. Negative values indicate high priority, positive values indicate low priority
P	Last CPU used, only meaningful in multi-CPU environment
%cpu	CPU time consumption percentage last updated to current
Time	Total CPU time used by the process, in seconds
time+	Total CPU time used by the process, Unit 1/100 sec
%MEM	Percentage of physical memory used by the process
VIRT	The total amount of virtual memory used by the process, in kilobytes. Virt=swap+res
SWAP	The size, in kilobytes, of the virtual memory that the process is using, swapped out.
Res	The size, in kilobytes, of the physical memory that the process used and was not swapped out. Res=code+data
CODE	The amount of physical memory the executable code occupies, in kilobytes
DATA	The amount of physical memory that is used by parts other than executable code (data segment + stack), in kilobytes
Shr	Shared memory size, in kilobytes
Nflt	Number of page faults
Ndrt	The number of pages that were modified the last time it was written to.
S	Process state. d= non-disruptive sleep state R= Run S= Sleep t= Tracking/Stopping z= Zombie Process
COMMAND	Command name/command line
Wchan	If the process is sleeping, the system function name in sleep is displayed
Flags	Task Flag, reference sched.h

Linux commands: Top command