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LINUX-Frequently used commands

top command　Real-time display of running processes.

Ｓyntax

top [Option]

The top command displays the currently running processes in order of increasing CPU utilization.
The display will be updated in real time.
Enter "q" to exit.

Frequently used options

-d <interval>	Specify the interval to update in "ss.tt seconds".
-n <Number of times>	Specify the number of times to repeat the display
-b	Batch mode The key operation is not accepted and execution continues until the number of times specified by "-n" or until it is killed by "CTRL+C". Useful for saving top results to a file, for example.
-s	Operates in secure mode（Does not accept "d" etc. during startup ）
-U <user>, -u <user>	Specify the user to monitor by name or ID
-p <Process ID>	Specify the process ID to monitor You can specify more than one, as in "-p number -p number" or "-p number, number".（Spaces can be omitted）
-c	Toggle the COMMAND column (far right) to show the program name or the command line（After starting up, use "c" to switch）
-i	Toggles between showing and not showing idle processes that are not running（Switch with "i" after launch）
-S	Specify the items to be used to sort the output（Default is CPU usage） The names of the items that can be specified are confirmed by using "top -O
-w <Number of digits>	Output width

Example: View file details.

$ su -
Password:
# top

<span style="font-size: 14px;">top - 11:29:12 up 41 days, 23:11,  1 user,  load average: 0.00, 0.01, 0.05
Tasks:  79 total,   1 running,  78 sleeping,   0 stopped,   0 zombie
%Cpu(s):  0.0 us,  0.2 sy,  0.0 ni, 99.8 id,  0.0 wa,  0.0 hi,  0.0 si,  0.0 st
KiB Mem:   1026932 total,   868020 used,   158912 free,   172824 buffers
KiB Swap:  2094076 total,        0 used,  2094076 free,   549148 cached

  PID USER      PR  NI  VIRT  RES  SHR S  %CPU %MEM    TIME+  COMMAND                               
    1 root      20   0 10644  820  688 S   0.0  0.1   0:45.88 init                                  
    2 root      20   0     0    0    0 S   0.0  0.0   0:00.10 kthreadd                              
    3 root      20   0     0    0    0 S   0.0  0.0   0:05.73 ksoftirqd/0                           
    5 root      20   0     0    0    0 S   0.0  0.0   0:00.00 kworker/u:0                           
    6 root      rt   0     0    0    0 S   0.0  0.0   0:00.83 migration/0                           
    7 root      rt   0     0    0    0 S   0.0  0.0   0:21.80 watchdog/0                            
    8 root      rt   0     0    0    0 S   0.0  0.0   0:00.53 migration/1                           
   10 root      20   0     0    0    0 S   0.0  0.0   0:35.34 ksoftirqd/1                           
   11 root      20   0     0    0    0 S   0.0  0.0   2:11.60 kworker/0:1                           
   12 root      rt   0     0    0    0 S   0.0  0.0   0:21.28 watchdog/1                            
…  …</span>

<span style="font-size: 14px;">top - 11:29:12 up 41 days, 23:11, 1 user, load average: 0.00, 0.01, 0.05

Tasks: 79 total, 1 running, 78 sleeping, 0 stopped, 0 zombie

%Cpu(s): 0.0 us, 0.2 sy, 0.0 ni, 99.8 id, 0.0 wa, 0.0 hi, 0.0 si, 0.0 st

KiB Mem: 1026932 total, 868020 used, 158912 free, 172824 buffers

KiB Swap: 2094076 total, 0 used, 2094076 free, 549148 cached

PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND

1 root 20 0 10644 820 688 S 0.0 0.1 0:45.88 init

2 root 20 0 0 0 0 S 0.0 0.0 0:00.10 kthreadd

3 root 20 0 0 0 0 S 0.0 0.0 0:05.73 ksoftirqd/0

5 root 20 0 0 0 0 S 0.0 0.0 0:00.00 kworker/u:0

6 root rt 0 0 0 0 S 0.0 0.0 0:00.83 migration/0

7 root rt 0 0 0 0 S 0.0 0.0 0:21.80 watchdog/0

8 root rt 0 0 0 0 S 0.0 0.0 0:00.53 migration/1

10 root 20 0 0 0 0 S 0.0 0.0 0:35.34 ksoftirqd/1

11 root 20 0 0 0 0 S 0.0 0.0 2:11.60 kworker/0:1

12 root rt 0 0 0 0 S 0.0 0.0 0:21.28 watchdog/1

… …</span>

PID	Process ID
USER	User name
PR	Process priority
NI	Process priority in nice values
VIRT	Memory usage size (kb)
RES	Actual memory usage size (kb)
SHR	Shared memory size (kb)
S	Process status
	R：Operation
	S：Sleep
	D：Sleep (not available)
	T：Stop in progress
	Z：Zombies
%CPU	CPU usage
%MEM	Memory usage
TIME+	Process uptime
COMMAND	Process commands

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