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Return value in script?

I use this script to return 0 when cpu load>80% and 1(256) when cpu<80%. And i call it in a C program like this:
sample.c
{
value_return=system("sh /home/dell/cpuload.sh");
printf ("value_return=%d",value_return)
}
And i run sample.c (maybe few times a second):
cpu>80%: 0 0 0 0 0 0...
cpu<80% 256 256 0 256 0 256 256... <-- Anyone know why?

#!/bin/sh
#/home/dell/cpuload.sh
LAST=""
STAT=`cat /proc/stat | grep cpu `
if [ -f /tmp/cpu_last ]; then
    LAST=`cat /tmp/cpu_last `
 
fi
awk -v b="$LAST" -v a="$STAT" '
    BEGIN {
        if ( b == "" ) {
            print "0";
            print a > "/tmp/cpu_last";
            exit;
        }
        split(a,data_a," ");
        split(b,data_b," ");
        d_u = data_a[2] - data_b[2];
        d_n = data_a[3] - data_b[3];
        d_s = data_a[4] - data_b[4];
        d_i = data_a[5] - data_b[5];
        load = 100 - (d_i/(d_u + d_s + d_n + d_i)*100);
	print a > "/tmp/cpu_last";	
	if ( load >= 80 ) {
                exit 0;
        } else {
                exit 1;
        }
    exit;}'

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Infinity08

The return value of 'system' is implementation defined. Usually, it returns 0 when the call completed successfully, and non-zero otherwise.

Infinity08

If you are on a UNIX-like system, then you could use WEXITSTATUS(value_return) to get the real exit code of the command.

Infinity08

So :

int value_return = system("sh /home/dell/cpuload.sh");
if (WIFEXITED(value_return)) {
  printf("value_return=%d", WEXITSTATUS(value_return));
}
else {
  printf("system call failed !");
  exit(1);
}

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KomaSatomi

ASKER

I use Linux (Ubuntu). Can i use that command?Could you please show me the completely command?

Infinity08

>> I use Linux (Ubuntu). Can i use that command?

Yes.

>> Could you please show me the completely command?

I did ;)

KomaSatomi

ASKER

Sorry.It display
warning: implicit declaration of function WEXITSTATUS
which lib i dont add yet?
IF my program C (so big) cant add any lib, is there other way to fix that problem?

Infinity08

WEXITSTATUS should be in :

#include <sys/wait.h>

KomaSatomi

ASKER

ok. i added that line and it display:
1 1 0 1 0 1 0...
Please check again.
I can open new question if you want.

Infinity08

>> Please check again.

Euhm. Isn't that what you wanted it to display ?

KomaSatomi

ASKER

No. i want it to display 1 1 1 1 1 1 in normal load (cpu<80%) and 0 0 0 0 0 in overload mode. sorry if i said not clearly.

KomaSatomi

ASKER

Or 256 256 256 256 256... in normal load. (not display 0 in normal load)

Infinity08

Ah, I see. I thought your question was about the 256 vs. 1.

I still don't see the problem though. It's not surprising that a CPU might go over 80% load very briefly, even when the system is not "in use". The script itself could be the cause.

KomaSatomi

ASKER

You mean the script has a problem? And there is no way to fix that?

Infinity08

I mean that it is normal that your CPU is used to its full potential. Even when a system is "idle", there are still certain tasks that need to be done (in the background), and they might take more than 80% of the CPU.

If you want to avoid the effect of small peaks, take averages over a certain time period (like a second for example), and use the averages to determine the load on the CPU.

KomaSatomi

ASKER

I got it. can you give me more little help?^^
How take averages? I can do it in script? It really too difficult to me.

Infinity08

You are already sampling the stat data, and comparing it with the previous sample. You just have to make sure that the delay between two samples is sufficiently large, like 1 second for example.

KomaSatomi

ASKER

You mean sleep 1;where i can add it?
But i have to call it maybe few times a second.So what i have to do?

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Infinity08

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KomaSatomi

ASKER

^^. It's hard to do as you said. Thank anyway.