hi all,

i am a newbie and have a very silly question about the difference between "ps" and "top".

i have a code which takes a long time to execute. initially the executable shows when i type "ps -a" or "ps -ef". but, after some time the executable disappears from this list. however, when i type "top" the executable shows up over there.

my question is: when does some executing process shows up in "top" only and not in "ps" ?

thanks in advance.

Have you tried piping the output of ps to grep? It would be like this:"ps -a" would certainly not show all processes, but ps -ef would - although some might be off the screen as ps doesn't wrap (unless you were to pipe it through less or something, like "ps -ef | less")

yes, i have tried ps -ef and also piping the output to less.
but still no luck

Hi,

What are the process having your machine?

which is need for the machine to alive and dependence up on your running application. This type of process only that all machine having. At the time some of the process only running not all process.

For example: init process should need for your machine because that is the main process in linux. This process not running continuously but its need to alive the machine.

you will start the xmms application(mp3 player). For this case, this application runs continuously. some time this process also not running continuously.

Finally all the process not running all the time.


'ps' command showing all process by time wise. which is having the all process. Its not care about the process is running or sleeping.

example:

[root@maniannam ~]# ps -ef
UID PID PPID C STIME TTY TIME CMD
</b>root 1 0 0 Oct17 ? 00:00:01 init [5] </b>
root 2 0 0 Oct17 ? 00:00:00 [kthreadd]
root 3 2 0 Oct17 ? 00:00:02 [migration/0]
root 4 2 0 Oct17 ? 00:00:33 [ksoftirqd/0]
root 5 2 0 Oct17 ? 00:00:00 [watchdog/0]
root 6 2 0 Oct17 ? 00:00:01 [migration/1]
root 7 2 0 Oct17 ? 00:00:25 [ksoftirqd/1]
root 8 2 0 Oct17 ? 00:00:00 [watchdog/1]
root 9 2 0 Oct17 ? 00:00:00 [events/0]
root 10 2 0 Oct17 ? 00:00:00 [events/1]
root 11 2 0 Oct17 ? 00:00:00 [khelper]
root 63 2 0 Oct17 ? 00:00:00 [kblockd/0]

mani 8927 1 0 13:56 ? 00:00:00 /bin/sh /usr/lib/firefox-2.0.0.16/firefox
mani 8946 8927 0 13:56 ? 00:00:00 /bin/sh /usr/lib/firefox-2.0.0.16/run-mozilla.sh /usr/lib/firefox-2.0.0.16/firefox-bin
mani 8951 8946 5 13:56 ? 00:04:10 /usr/lib/firefox-2.0.0.16/firefox-bin
mani 8965 1 0 13:56 ? 00:00:00 /bin/sh /usr/lib/thunderbird-2.0.0.16/thunderbird
mani 8969 8965 0 13:56 ? 00:00:00 /bin/sh /usr/lib/thunderbird-2.0.0.16/run-mozilla.sh /usr/lib/thunderbird-2.0.0.16/thunderbird-bin
mani 8974 8969 1 13:56 ? 00:01:09 /usr/lib/thunderbird-2.0.0.16/thunderbird-bin
mani 9117 8951 39 14:20 ? 00:20:34 /usr/lib/nspluginwrapper/npviewer.bin --plugin /usr/lib/mozilla/plugins/libflashplayer.so --connection /org/w
<b>root 9269 8888 0 14:56 pts/1 00:00:07 /usr/libexec/xmms</b>
root 9317 8888 0 15:12 pts/1 00:00:00 ps -ef


'top' command showing running process in the top order. That's why you can see the some of the process in the first line after some time it will go second or third its dependences on the process status.

S- sleeping process
R- Running process
D- going to die

example :
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
9117 mani 20 0 96212 29m 9148 S 9 1.0 20:51.01 npviewer.bin
9325 mani 20 0 55004 6900 5260 R 7 0.2 0:04.04 xmms
2519 root 20 0 391m 75m 11m R 3 2.5 52:32.31 X
8951 mani 20 0 273m 101m 22m S 1 3.3 4:17.66 firefox-bin
7 root 15 -5 0 0 0 S 0 0.0 0:25.69 ksoftirqd/1
9323 root 20 0 2272 1020 784 R 0 0.0 0:00.31 top
1 root 20 0 2112 656 572 S 0 0.0 0:01.50 init
2 root 15 -5 0 0 0 S 0 0.0 0:00.00 kthreadd


Please forgive me for my english. I hope it will helpful......


Regards,
maniannam