Top command details

One 、 brief introduction

top Commands are often used to monitor Linux The operation of the server , It can display the memory usage of each process of the server in real time .

top [-d number] | top [-bnp]

Easy to use ：

top

The results are as follows ： 

  If we want to know top Details of the command , You can use commands ：

info top

The result is shown in Fig. ：

  The red box in the above figure shows top Some parameters of the command , The specific meaning of parameters will be explained later .

We see one above  DESCRIPTION, Translate as follows ：

top The program provides a dynamic real-time view of the running system .

It can display system summary information as well as the current Linux A list of processes or threads managed by the kernel . The type of system summary information displayed and the type of information displayed for the process 、 The order and size are user configurable , And it can be configured during restart .

The program provides a limited interactive interface for process operation , It provides a broader interface for personal configuration , It covers all aspects of its operation . Although mentioned in this document top, But you can name the program as you like . The new name （ It could be an alias ） Will be reflected in top On the screen , And use... When reading and writing configuration files .

  Two 、 Detailed explanation of output parameters

We use top After the command , stay linux Dynamically refresh the resource usage of each process on the server , So many parameters above , What do you mean by that ？

1.PID

Name              meaning
PID             process id
PPID             The parent process id
RUSER            Real user name
UID     The user of the process owner id
USER     User name of the process owner
GROUP     The group name of the process owner
TTY     The terminal name of the startup process . Processes that are not started from the terminal are shown as ?
PR     priority
NI    nice value . Negative value indicates high priority , A positive value indicates a low priority
P     Last used CPU, Only in many CPU It makes sense in the environment
%CPU     Last updated to now CPU Percentage of time used
TIME     Used by process CPU Total time , Unit second
TIME+     Used by process CPU Total time , Company 1/100 second
%MEM     Percentage of physical memory used by the process
VIRT     Total virtual memory used by the process , Company kb.VIRT=SWAP+RES
SWAP     The virtual memory used by the process , The size changed out , Company kb
RES     Used by process 、 Physical memory size not swapped out , Company kb.RES=CODE+DATA
CODE     The size of the physical memory occupied by the executable code , Company kb
DATA     Beyond the executable code ( Data segment + Stack ) The amount of physical memory occupied , Company kb
SHR     Shared memory size , Company kb
nFLT     Number of page errors
nDRT     Last write to now , Number of pages modified .
S     Process status .D= Uninterrupted sleep R= function S= sleep T= track / stop it Z= Zombie process
COMMAND     Command name / Command line
WCHAN     If the process is sleeping , The system function name in sleep is displayed
Flags     Mission signs

3、 ... and 、 Parameters,

1. -d

If we add -d Parameters , The display is the same as above , It's just that the dynamic refresh time is different .-d The parameter represents the number of seconds to refresh the page , The default is 5 Second . If you want to change it to 10 Seconds to refresh , Then you can ：

top -d 10

2. ？

In the use of top On the dynamic page after the command , If we want to see the sort parameters , We can use ?, It is shown as follows ：

Like the bottom q , It means we are top Display page of command , Press q Then exit the display .

 3. M

ditto . stay top Command display page , The default is CPU The load is highly ordered , If we want to sort by memory usage , stay top The display page after the command , We press M（ Be case sensitive ）：

 4. Other commands that can be used to display pages

P In order to CPU The load used is highly ordered .N With pid Order of size .T The cumulative time sequence used by the process .q sign out top command , perhaps Ctrl + only .

5. -p

top -p 12345

View the specified pid Resources used ：

Reference resources ：Linux in top Command parameter details