1) top command:
top is most common keyword through which you can find out which users are connected, which processes are running, which processes are taking more CPU or memory and many more. Simply issue "top" command from operating system to check the output of the command.
Sample top output which by default displays the processes in the order of CPU usage and it will display a continually updating report of system resource usage.
$top
top - 13:43:14 up 231 days, 12:16, 2 users, load average: 2.25, 2.85, 3.00
Tasks: 679 total, 2 running, 677 sleeping, 0 stopped, 0 zombie
Cpu(s): 7.4%us, 0.5%sy, 0.0%ni, 90.3%id, 1.6%wa, 0.1%hi, 0.1%si, 0.0%st
Mem: 132099408k total, 131273300k used, 826108k free, 2509704k buffers
Swap: 133122612k total, 139832k used, 132982780k free, 115727764k cached
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
23555 oracle 16 0 20.5g 883m 879m R 99 0.7 3:02.56 oracle
29158 oracle 15 0 20.5g 113m 108m S 38 0.1 0:38.20 oracle
1271 oracle 15 0 13112 1436 712 R 4 0.0 0:00.02 top
8617 oracle 16 0 10.1g 1.3g 1.3g S 2 1.1 139:19.24 oracle
14894 oracle 15 0 1243m 35m 25m S 2 0.0 36:45.03 oracle
14896 oracle 15 0 1246m 45m 36m S 2 0.0 58:51.09 oracle
15985 oracle 15 0 1245m 282m 274m S 2 0.2 19:09.18 oracle
19349 grid RT 0 482m 288m 51m S 2 0.2 1693:51 ocssd.bin
20320 oracle 18 0 1647m 39m 15m S 2 0.0 2155:21 oraagent.bin
31010 oracle 15 0 20.5g 37m 34m S 2 0.0 0:00.73 oracle
32298 oracle 15 0 20.5g 44m 40m S 2 0.0 0:00.44 oracle
1 root 15 0 10328 688 580 S 0 0.0 20:24.76 init
2 root RT -5 0 0 0 S 0 0.0 0:22.95 migration/0
3 root 34 19 0 0 0 S 0 0.0 0:00.63 ksoftirqd/0
4 root RT -5 0 0 0 S 0 0.0 0:00.19 watchdog/0
5 root RT -5 0 0 0 S 0 0.0 1:25.47 migration/1
6 root 34 19 0 0 0 S 0 0.0 0:00.82 ksoftirqd/1
7 root RT -5 0 0 0 S 0 0.0 0:00.29 watchdog/1
8 root RT -5 0 0 0 S 0 0.0 0:23.55 migration/2
9 root 34 19 0 0 0 S 0 0.0 0:00.80 ksoftirqd/2
10 root RT -5 0 0 0 S 0 0.0 0:00.33 watchdog/2
11 root RT -5 0 0 0 S 0 0.0 0:32.52 migration/3
12 root 34 19 0 0 0 S 0 0.0 0:00.76 ksoftirqd/3
13 root RT -5 0 0 0 S 0 0.0 0:00.31 watchdog/3
14 root RT -5 0 0 0 S 0 0.0 1:10.23 migration/4
15 root 34 19 0 0 0 S 0 0.0 0:08.80 ksoftirqd/4
16 root RT -5 0 0 0 S 0 0.0 0:00.21 watchdog/4
17 root RT -5 0 0 0 S 0 0.0 1:32.78 migration/5
18 root 34 19 0 0 0 S 0 0.0 0:06.73 ksoftirqd/5
19 root RT -5 0 0 0 S 0 0.0 0:00.27 watchdog/5
20 root RT -5 0 0 0 S 0 0.0 1:06.50 migration/6
21 root 34 19 0 0 0 S 0 0.0 0:06.41 ksoftirqd/6
22 root RT -5 0 0 0 S 0 0.0 0:00.34 watchdog/6
23 root RT -5 0 0 0 S 0 0.0 1:20.30 migration/7
24 root 34 19 0 0 0 S 0 0.0 0:06.87 ksoftirqd/7
25 root RT -5 0 0 0 S 0 0.0 0:00.28 watchdog/7
26 root RT -5 0 0 0 S 0 0.0 0:20.32 migration/8
27 root 34 19 0 0 0 S 0 0.0 0:01.32 ksoftirqd/8
We can modify the output of top command while it is running.
A)Sort top Output command
We can sort top output command by pressing O (Uppercase O) while it is running. While top command is running press capital O will display the output like below.
Current Sort Field: K for window 1:Def Select sort field via field letter, type any other key to return a: PID = Process Id b: PPID = Parent Process Pid c: RUSER = Real user name d: UID = User Id e: USER = User Name f: GROUP = Group Name g: TTY = Controlling Tty h: PR = Priority i: NI = Nice value j: P = Last used cpu (SMP) * K: %CPU = CPU usage l: TIME = CPU Time m: TIME+ = CPU Time, hundredths n: %MEM = Memory usage (RES) o: VIRT = Virtual Image (kb) p: SWAP = Swapped size (kb) q: RES = Resident size (kb) r: CODE = Code size (kb) s: DATA = Data+Stack size (kb) t: SHR = Shared Mem size (kb) u: nFLT = Page Fault count v: nDRT = Dirty Pages count w: S = Process Status x: COMMAND = Command name/line y: WCHAN = Sleeping in Function z: Flags = Task FlagsPressing Capital M (M) will sort the output by memory usage. Sample output by pressing M.Note1: If a selected sort field can't be shown due to screen width or your field order, the '<' and '>' keys will be unavailable until a field within viewable range is chosen. Note2: Field sorting uses internal values, not those in column display. Thus, the TTY & WCHAN fields will violate strict ASCII collating sequence. (shame on you if WCHAN is chosen)
[oracle@DC-DB-01 ~]$ top top - 14:24:24 up 231 days, 12:57, 2 users, load average: 4.57, 3.27, 2.96 Tasks: 673 total, 4 running, 669 sleeping, 0 stopped, 0 zombie Cpu(s): 10.4%us, 0.7%sy, 0.0%ni, 87.0%id, 1.3%wa, 0.1%hi, 0.4%si, 0.0%st Mem: 132099408k total, 131249840k used, 849568k free, 2509836k buffers Swap: 133122612k total, 139832k used, 132982780k free, 115721144k cached PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 3503 oracle 15 0 10.1g 3.7g 3.7g S 0 3.0 162:48.84 oracle 3505 oracle 15 0 10.1g 3.6g 3.6g S 0 2.9 40:14.52 oracle 3501 oracle 15 0 10.1g 3.6g 3.6g S 0 2.9 51:14.55 oracle 8598 oracle 15 0 10.1g 3.4g 3.4g S 0 2.7 37:51.43 oracle 1901 oracle 15 0 20.5g 3.1g 3.1g S 0 2.5 0:03.33 oracle 9310 oracle 15 0 10.1g 2.9g 2.9g S 0 2.3 129:22.91 oracle 8590 oracle 15 0 10.1g 2.8g 2.8g S 0 2.2 36:25.79 oracle 8566 oracle -2 0 10.1g 2.6g 2.6g S 0 2.1 52:32.13 oracle 8570 oracle -2 0 10.1g 2.6g 2.6g S 0 2.1 48:43.81 oracle 8580 oracle 15 0 10.1g 2.6g 2.6g S 0 2.0 15:02.37 oracle 18507 root 15 0 3118m 2.6g 20m S 0 2.0 155:36.15 ohasd.bin 8582 oracle 15 0 10.1g 2.6g 2.6g S 0 2.0 14:58.25 oracle 8584 oracle 15 0 10.1g 2.6g 2.5g S 0 2.0 14:51.78 oracle 3499 oracle 15 0 10.1g 2.3g 2.3g S 0 1.8 43:55.73 oracle
If you want to sort by how long they processes have been running then press S (capital S).
If you want to sort by CPU usage then press P (capital P).
B)Sort in Reverse Order by using top
If you want to display the sort order in reverse order then press R (capital R).
C)Not to Display Idle Processes
If you no longer want to display idle processes then press r (Small r). Hit them i again to see them again.
D)Kill a process while running top
If you want to kill a process then first note down the PID and then while running top press "k" which will ask you for the process id. Type the process ID. If you have the privilege to kill that particular PID, it will get killed successfully.
E)Change priority of processes while running top
If you want to change the priority of a process but not kill the process then simply press "r" (renice). This will ask PID for renice, enter the PID and priority. The priority value can be -20 (most favorable scheduling) to 19 (least favorable).
F)Display selected user in top output
By using "top -u" you can display a specific user processes.
For example:
$ top -u grid top - 14:56:30 up 231 days, 13:29, 2 users, load average: 3.11, 3.20, 2.99 Tasks: 676 total, 2 running, 674 sleeping, 0 stopped, 0 zombie Cpu(s): 7.3%us, 0.6%sy, 0.0%ni, 90.9%id, 1.2%wa, 0.0%hi, 0.1%si, 0.0%st Mem: 132099408k total, 131272684k used, 826724k free, 2509928k buffers Swap: 133122612k total, 139832k used, 132982780k free, 115732404k cached PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 20159 grid 17 0 1795m 195m 20m S 1 0.2 4473:22 java 19349 grid RT 0 482m 288m 51m S 1 0.2 1694:26 ocssd.bin 19095 grid 18 0 825m 33m 14m S 0 0.0 1062:20 oraagent.bin 1926 grid 16 0 466m 20m 18m S 0 0.0 0:12.13 oracle 4378 grid 17 0 469m 20m 17m S 0 0.0 0:00.02 oracle 4413 grid 18 0 469m 18m 16m S 0 0.0 0:00.02 oracle 6748 grid 16 0 470m 31m 28m S 0 0.0 0:02.05 oracle 8600 grid 16 0 466m 23m 21m S 0 0.0 13:40.14 oracle 15046 grid 16 0 466m 19m 17m S 0 0.0 2:13.50 oracle 17145 grid 16 0 81228 12m 9264 S 0 0.0 6:33.89 tnslsnr 17617 grid 16 0 470m 31m 28m S 0 0.0 0:02.03 oracle 17645 grid 16 0 81216 12m 9208 S 0 0.0 0:33.69 tnslsnr 19120 grid 15 0 249m 53m 8636 S 0 0.0 6:47.27 gipcd.bin 19132 grid 15 0 261m 56m 7240 S 0 0.0 6:46.97 mdnsd.bin 19146 grid 15 0 320m 65m 11m S 0 0.1 14:16.95 gpnpd.bin 19409 grid 18 0 192m 15m 8216 S 0 0.0 5:05.33 diskmon.bin 19600 grid 15 0 403m 67m 12m S 0 0.1 17:01.10 evmd.bin 19687 grid 15 0 471m 18m 16m S 0 0.0 10:00.15 oracleYou can display only specific process with given PIDs using top -p
$ top -p 1926, 17645, 19349 top - 15:01:51 up 231 days, 13:34, 2 users, load average: 2.46, 2.76, 2.85 Tasks: 3 total, 0 running, 3 sleeping, 0 stopped, 0 zombie Cpu(s): 6.3%us, 0.6%sy, 0.0%ni, 92.8%id, 0.2%wa, 0.0%hi, 0.1%si, 0.0%st Mem: 132099408k total, 131216440k used, 882968k free, 2509936k buffers Swap: 133122612k total, 139832k used, 132982780k free, 115734276k cached PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 19349 grid RT 0 482m 288m 51m S 1 0.2 1694:29 ocssd.bin 1926 grid 15 0 466m 20m 18m S 0 0.0 0:12.14 oracle 17645 grid 16 0 81216 12m 9208 S 0 0.0 0:33.69 tnslsnrG)Display all CPUs/ Cores in the top output
While running top command, pressing 1 (one) will break the CPU down and show details for all the individual CPUs running on the system.
$ top top - 15:03:17 up 231 days, 13:36, 2 users, load average: 2.23, 2.60, 2.79 Tasks: 671 total, 5 running, 666 sleeping, 0 stopped, 0 zombie Cpu0 : 26.4%us, 0.0%sy, 0.0%ni, 73.6%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st Cpu1 : 10.7%us, 0.7%sy, 0.0%ni, 88.6%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st Cpu2 : 0.7%us, 0.0%sy, 0.0%ni, 99.3%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st Cpu3 : 42.0%us, 0.3%sy, 0.0%ni, 57.7%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st Cpu4 : 1.3%us, 0.0%sy, 0.0%ni, 98.7%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st Cpu5 : 0.7%us, 0.0%sy, 0.0%ni, 99.3%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st Cpu6 : 8.7%us, 0.7%sy, 0.0%ni, 90.6%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st Cpu7 : 0.3%us, 1.0%sy, 0.0%ni, 98.7%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st Cpu8 : 35.6%us, 0.0%sy, 0.0%ni, 64.4%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st Cpu9 : 0.7%us, 0.3%sy, 0.0%ni, 98.3%id, 0.3%wa, 0.0%hi, 0.3%si, 0.0%st Cpu10 : 1.0%us, 0.3%sy, 0.0%ni, 97.7%id, 0.7%wa, 0.0%hi, 0.3%si, 0.0%st Cpu11 : 2.0%us, 0.0%sy, 0.0%ni, 98.0%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st Cpu12 : 1.0%us, 0.0%sy, 0.0%ni, 99.0%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st Cpu13 : 3.3%us, 0.3%sy, 0.0%ni, 96.3%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st Cpu14 : 16.1%us, 0.7%sy, 0.0%ni, 79.6%id, 3.3%wa, 0.0%hi, 0.3%si, 0.0%st Cpu15 : 0.0%us, 0.0%sy, 0.0%ni, 99.7%id, 0.0%wa, 0.0%hi, 0.3%si, 0.0%st Cpu16 : 9.4%us, 0.0%sy, 0.0%ni, 90.6%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st Cpu17 : 9.0%us, 0.3%sy, 0.0%ni, 90.7%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st Cpu18 : 0.0%us, 0.0%sy, 0.0%ni, 99.7%id, 0.3%wa, 0.0%hi, 0.0%si, 0.0%st Cpu19 : 18.4%us, 5.4%sy, 0.0%ni, 76.3%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st Cpu20 : 17.1%us, 0.0%sy, 0.0%ni, 82.9%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st Cpu21 : 27.2%us, 0.7%sy, 0.0%ni, 69.8%id, 1.3%wa, 0.0%hi, 1.0%si, 0.0%st Cpu22 : 0.3%us, 0.0%sy, 0.0%ni, 99.7%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st Cpu23 : 3.6%us, 1.0%sy, 0.0%ni, 94.4%id, 0.3%wa, 0.0%hi, 0.7%si, 0.0%st Mem: 132099408k total, 131368388k used, 731020k free, 2509944k buffers Swap: 133122612k total, 139832k used, 132982780k free, 115734812k cached
H)Change Refresh Interval in top output
Whenever you issue top command you will notice in every 3 seconds the output is being refreshed. You can change the update output frequency by pressing d (small d). Upon pressing d it will display an interactive prompt. Enter the time in seconds and then press enter. Now it will update based on the seconds given by you. If you want to update the output on-demand then press space bar.
I)Highlight running processes
You can highlight running processes by pressing z or b. You can press z or b and then check the output while running top.
J)Display absolute path and arguments of the command running
While running top command output press small c. It will show / hide command absolute path, and arguments.
K)Quit top after specific number of iterations
Top continuously displays output in every 3 seconds until you press q. If you would like to view only a certain iteration and want the top to exit automatically use -n option.
For example if you want to display 3 iterations of unix top command output and then exit then issue.
$ top -n 3
L)Executing top Command in batch mode
If you want to execute top command in the batch mode then use -b option with top command for example:
$ top -b -n 3
This is very useful if you want to save the top command output into a file.
For example the following command
$ top -b -n 3 >a.txt
will create a file named a.txt which contains 3 iterations of top command output.
M)Split top output into multiple panels
While running top output pressing A (capital A) will split top output into multiple panels. You can cycle through these windows using 'a'.
N)Decease number of processes to display
By default the value of n is 0 which means all tasks are displayed. But you can limit the number of tasks to display. If you want to display 4 tasks at a time then press "n". The interactive mode will appear and just type 4.
Maximum tasks = 0, change to (0 is unlimited): 4
O)Toggle top header while displaying top command output
You will increase the number of processes displayed by top command in your window. While running top command.
Press "l" – to hide / show the load average. 1st header line.
Press "t" – to hide / show the CPU states. 2nd and 3rd header line.
Press "m" – to hide / show the memory information. 4th and 5th line.
P)Save top configuration settings
You can save the top configuration settings to a file by pressing W (capital W) while running top output. After you press W it will display output like,
Wrote configuration to '/home/oracle/.toprc'
You can check the content of the file by,
$ less /home/oracle/.toprc
In another post I will show you details about vmstat, iostat, ps and lsof commands.
