Linux Common Commands-top

Linux Common Commands-top

The top command displays the status of the process in real time. The default state shows CPU-intensive processes and is updated every 5 seconds . You can use the digital size of the PID, age (), time (), Resident memory usage (), and how long the process consumes the CPU from the start.

Top-20:59:18 up 4 days, 4:47, 1 user, Load average:0.00, 0.00, 0.00TASKS:65 Total, 2 running, sleeping, 0   Stopped, 0 zombiecpu (s): 0.2%us, 0.1%sy, 0.0%ni, 99.6%id, 0.1%wa, 0.0%hi, 0.0%si, 0.0%stmem:500472k Total, 282756k used, 217716k free, 82496k buffers swap:0k total, 0k used, 0k free, 61052k cached                                                                 PID USER PR NI VIRT RES SHR S%cpu%MEM time+ COMMAND                                                                975 Root 0 756m 10m 8008 S 0.2 2.1 9:12.19 Aliyundun                                                                  991 Root 0 768m 9320 7164 S 0.2 1.9 5:19.35 Alihids                                                            842 Root 0 463m 2588 1888 S 0.1 0.5 2:43.88 aliyundunupdate                                            1 root 0 19232 1512 1224 S 0.0 0.3 0:00.65 Init                           2 Root 0 0 0 0 S 0.0 0.0 0:00.01 Kthreadd                                                                3 root RT 0 0 0 0 S 0.0 0.0 0:00.00 migration/0                                                                4 Root 0 0 0 0 S 0.0 0.0 0:00.71 ksoftirqd/0 5 root RT 0 0 0 0 S 0.0 0.0 0:00.00 migratio n/0 6 root RT 0 0 0 0 S 0.0 0.0 0:00.5 5 watchdog/0 7 Root 0 0 0 0 S 0.0 0. 0 0:12.40 events/0 8 root 20 0 0 0 0    S 0.0 0.0 0:00.00 cgroup 9 root 20 0 0   0 0 S 0.0 0.00:00.00 khelper Root 0 0 0 0 S 0     .0 0.0 0:00.00 netns root 20 0 0 0     0 S 0.0 0.0 0:00.00 async/mgr Root 20 0      0 0 0 S 0.0 0.0 0:00.00 pm Root                                                                  0 0 0 0 S 0.0 0.0 0:00.00 Xenwatch                                                                    Root 0 0 0 0 S 0.0 0.0 0:00.00 Xenbus                                                               Root 0 0 0 0 S 0.0 0.0 0:01.22 sync_supers                                                         Root 0 0 0 0 S 0.0 0.0 0:01.14 Bdi-default      Root 0 0 0 0 S 0.0 0.0 0:00.00 kintegrityd/0                                                                 Root 0 0 0 0 S 0.0 0.0 0:00.18 kblockd/0                                                                    Root 0 0 0 0 S 0.0 0.0 0:00.00 kacpid                                                              Root 0 0 0 0 S 0.0 0.0 0:00.00 kacpi_notify   Root 0 0 0 0 S 0.0 0.0 0:00.00 kacpi_hotplug

If you want to increase the priority of a process, you can pass commands renice if you have a process that consumes too much CPU resources kill .

• Top displays the meanings of each column that appears:

  PID: Process Descriptor
  User: owner of the process
  PRI: priority of the process
  NI: nice level
  SIZE: process-owned memory (includes code segment + data segment + stack segment)
  RSS: Physical Memory usage
  VIRT(Virtul memory usage): The amount of virtual memory the process requires
  RES (Resident memory usage): Resident RAM
  SHARE: Physical memory space shared with other processes
  STAT: The state of the process, with s=sleeping,r=running,t=stopped or traced,d=interruptible sleep ( non-disruptive sleeping state ), z= Zombie
  %cpu: CPU usage
  %MEM: Use of physical memory
  Time : Total CPU elapsed by the process
  Command : commands for the process

• Common commands:

(1) T: Used to show the total statistics, that is, the following two lines

Tasks:  65 total,   2 running,  63 sleeping,   0 stopped,   0 zombieCpu(s):  0.2%us,  0.1%sy,  0.0%ni, 99.6%id,  0.1%wa,  0.0%hi,  0.0%si,  0.0%st

(2)m: Whether the user displays memory information, which is the following two lines

Mem:    500472k total,   282756k used,   217716k free,    82496k buffers    Swap:        0k total,        0k used,        0k free,    61052k cached

(3)a: According to a single window to switch to a multi-window, you can see four different windows, you can use A or W to switch multiple windows. The names of the four windows were:def,job,mem,usr

(4)F: into a dynamic configuration top screen, you can configure the top according to your preference

(5)o: sort the existing configuration of top (order)

(6)R: using the Renice command

(7)K: Use the KILL command

• How to use the top command line

(1) Batch processing mode

Plus -b , when top is displayed, the results of each display are printed out, and the last result is not flushed out.

(2) Display information for a process

$ top -p pid

If it is multiple processes, as follows:

$ top -p pid1,pid2,pid3

(3) Displaying process information for a user

$ top -u username

(4) Displaying thread information, not process information

(5) Set the time of the brush screen (in s)

$ top -d ntime

Linux common Commands-top