getting total CPU's idle

happy78 · 10-20-2005, 05:28 PM

Hi guys,

I'm having problem retrieving the the correct total cpu's ide with this command: top -n 1.

Sometimes, I'm able to retrieve the total cpu's idle of my machine by doing this:
cpus=($(top -b -n 1))
echo ${cpus[39]} #>> /tmp/$1

BASED on this output of "top -n 1":

15:22:56 up 86 days, 9:04, 11 users, load average: 0.06, 0.05, 0.01
127 processes: 125 sleeping, 1 running, 1 zombie, 0 stopped
CPU states: cpu user nice system irq softirq iowait idle
total 0.2% 0.0% 0.2% 0.0% 0.0% 0.0% 99.5%
cpu00 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 100.0%
cpu01 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 100.0%
cpu02 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 100.0%
cpu03 0.9% 0.0% 0.9% 0.0% 0.0% 0.0% 98.0%

So, at index cpus[39] the idle value is: 99.5%
That's correct.
But once in awhile the out put of "top -n 1" returns different output:

15:12:35 up 52 min, 3 users, load average: 0.29, 0.17, 0.09
83 processes: 81 sleeping, 1 running, 1 zombie, 0 stopped
CPU states: cpu user nice system irq softirq iowait idle
total 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 100.0%
cpu00 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 100.0%
cpu01 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 100.0%
cpu02 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 100.0%
cpu03 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 100.0%
This output is missing Time like the one. So, that shifted the position of cpu idle. Therefore, at cpus[39], the value is cpu00, instead of 100.0%

[/B]Is there any command that can retrieve cpu's total idle time better than "top -n 1"[/B]

Quigi · 10-20-2005, 07:38 PM

You could skip to the relevant line, e.g.,

Code:

cpus=`top -n 1 | tail +3`

or

Code:

cpus=`top -n 1 | grep ^total`

Then it's more reliably the same element (and easier to count!). My "top" output differs, but yours should be $cpus[8]. You can use $(...) instead of `...`.

happy78 · 10-20-2005, 08:25 PM

Hi
thank you for your response.
That helps alot, and I also have other solution:

let freeMB=`free -m | tail -2 | head -1 | awk '{print $4}'`
cpus=`top -n 1| head -4 | tail -1 | awk '{print $8}'`

echo $freeMB
echo ${cpus}

But I have a java program waiting to catch freeMB's and cpus' value. However, only freeMB's value is captured, and cpus' value isn't.
is there a problem with stdin?

Tinkster · 10-20-2005, 09:22 PM

Try that one (even though yours SHOULD work, too):

Code:

top -n 1 | awk '/cpu/ && $8 ~ "[0-9]" {print $8}'

Cheers,
Tink

happy78 · 10-20-2005, 09:25 PM

thank you for replying..
yes it works..
but now i run into a problem with java and linux...
java is waiting for my script to echo back with cpu's and freeMem's value....however, only freeMem's is caught..
looks like tty is lost..any suggestion?

happy78 · 10-20-2005, 09:45 PM

It's ok I fixed the problem by adding -b infront of "top"