Unable to read cmd line from sh file using Java

[david_1234]

Hello ,
I'm having a strange problem
I'm trying to read the CPU load using this commnad:

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top -n1 | grep "%Cpu"

when I try to use this java code :

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 try 
        {
            ProcessBuilder GetCPU = new ProcessBuilder ("sudo" , top" ,"-n1","grep" , "%Cpu");
          //*2  ProcessBuilder GetCPU = new ProcessBuilder ("sudo" , sh" , "/home/pi/Desktop/CPU.sh");
            GetCPU.redirectErrorStream(true);
            Process CPU = GetCPU.start();
            BufferedReader CPUr = new BufferedReader (new InputStreamReader(CPU.getInputStream()));
            line = CPUr.readLine();
            System.out.println("CPU is - " + line);
        }

I'm geting this answer:

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CPU is - top: unknown option '|'

when I try to run a sh file using the same command (which work on cmd) - mark as *2 at the code
I'm getting this error:

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CPU is - 'unknown': I need something more specific.

what am I doing wrong ,what am I missing?

Thanks ,

[DougieLawson]

You have to build two processes. One to run the top command. One to run the grep (although it may be more pythonic to use the python3 regex library rather than spawning a grep process).

You then do some plumbing to pipe the stdout from the top process to the stdin of the grep process.

http://queirozf.com/entries/python-3-su ... s-together

[david_1234]

The problem is that the main code is JAVA and I need to keep the answer and do some work with the numbers

I don't want to start using python from java - I think it will complicate things - no ?

isn't better to use only 1 language?


Thanks ,

[DougieLawson]

Sorry it's so rare to see a Java question on here, nobody uses Java.

Java has a regex library. Java has a way to pipe output from a subprocess to another process. Basically stop using grep.

Example #8 here: https://www.programcreek.com/java-api-e ... r.Redirect

[PeterO]

Would it be easier to just read and parse /proc/stat ?
PeterO

[david_1234]

I don't have this file \ library.
do I need to install something?

[DougieLawson]

I don't have this file \ library.
do I need to install something?

Eh? It's a virtual filesystem that's instantiated as part of booting the Linux kernel. Try cat /proc/stat from a LXTerminal.

[david_1234]

Ok
now I see it

but now what ?
this is what I ask here
https://www.raspberrypi.org/forums/view ... 7#p1562897

what do I need to calcualte in order to see the current CPU use?
I guess something from this line ?

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12705560 1075 1114248 131286844 258837 0 58030 0 0 0

if I take the 2nd value and devide it from the 1st one?
will this give me the CPU current use?

because when I do this I get 0.08 --> 8% and on the monitor I can see it's around 8 i

is this finally the answer?

Thanks ,

[DougieLawson]

Read the code for the top command. https://github.com/mmalecki/procps/blob/master/top.c

[david_1234]

you want me to read ~3100 lines of code?
maybe you can point me to the answer ?

I can only assume you know the answer

Thanks ,

[PeterO]

google /proc/stat

[david_1234]

this is what I did for the last hour
finally made this solution according to this explain
https://supportcenter.checkpoint.com/su ... id=sk65143

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 String CpuFileName = "/proc/stat";
        String line = null;
        String strArray[] = new String[12];
        double CpuLoad = 0;
	
	try {

            FileReader fileReader1 = new FileReader(CpuFileName);
            BufferedReader bufferedReader1 = new BufferedReader(fileReader1);
            line = bufferedReader1.readLine (); //get only the first line 
            
            System.out.println(line);
             
            bufferedReader1.close(); //finish reading after the first line 
            
            strArray= line.split(" ");
                       
            double TotalCPU = 0;
            double IdleCPU = 100;
            
            for (int i=2 ; i<12 ; i++)
            {
            TotalCPU = TotalCPU + Integer.parseInt(strArray[i]); 
             }
            IdleCPU = Integer.parseInt(strArray[5]); //the palce of the idle 
            System.out.println("CPU Idle: " + IdleCPU);
            System.out.println ("Total is - " + TotalCPU);
            
            CpuLoad = (100 - ((IdleCPU / TotalCPU) * 100));
            
            System.out.println ("Current CPU use is - " + CpuLoad + "%");
            
            
    }

        catch(IOException ex) {
            System.out.println(ex);
        }

it's seem to work
I get only around 9% - and on the monitor I see also aroud 9%
I will try to run some things on the PI to see if this is working OK when CPU is working harder


if you find something wrong in the code ( or mayeb thr logic of it ) - let me know



***** update
it's not working
I get the same value all the time , even when the monitor show much higher CPU load

Untitled.png (95.77 KiB) Viewed 2886 times

Thanks ,

[PeterO]

You have not taken notice of this important piece of information....

"All of the numbers reported in this file are aggregates since the system first booted."

PeterO

[david_1234]

So this doesn't help me to get to the solution I need either

I think Linux moto should be
"Let's make things more complicated....."

so maybe you have any idea how to get the cpu load (the same value I get in the monitor ) ?

Thanks ,

[PeterO]

So this doesn't help me to get to the solution I need either

I think Linux moto should be
"Let's make things more complicated....."

so maybe you have any idea how to get the cpu load (the same value I get in the monitor ) ?

Thanks ,

I absolutely tells you how to get the data you want. Maybe you don't understand it, in which case ask more questions rather than that having a hissy fit and going off in a huff......

If you look closely at the numbers in /proc/stat you will see they only ever increase. You need to get a set of numbers (setA), wait a second and get another set of numbers (setB). Then subtract setA from SetB and it will give you the usage data for the last second. Then move setB to SetA, wait another second, get a new setB and subtract .... rinse and repeat !

PeterO

[david_1234]

OK -
I can do this

just to see I got it right
on t0 I have column1 , column2 , column3 ....
on t1 I have column1_1 , column2_1 , column3_1

then I sub columns1_1-column1 .....
I get a "new" line with 7 values\numbers
and from there I do waht I did before?

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CpuLoad = (100 - ((IdleCPU / TotalCPU) * 100));

?

did I understand you correctly?

Thanks ,

[PeterO]

Sounds reasonable.
PeterO

[david_1234]

whould you do it different? (Logic speaking)
Thanks ,

[PeterO]

whould you do it different? (Logic speaking)
Thanks ,

I wouldn't be doing it in Java for a start !
I have a C/GTK3 version that drives a "Load Meter"

Meter3.png (14.9 KiB) Viewed 2803 times

PeterO

[addeswe]

Usually I don't really like to post bad code. However, I have no idea what you want to do with this. So I'll just show you an easy way to do it.

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		List<String> load = new ArrayList<String>();
		ProcessBuilder pb = new ProcessBuilder("uptime");
		Process p = pb.start();
		Pattern pattern = Pattern.compile("\\d\\.\\d\\d");
		String loads = new BufferedReader(new InputStreamReader(p.getInputStream())).readLine();
		Matcher match = pattern.matcher(loads);
		while (match.find()) {
			load.add(match.group());
		}
		System.out.println(load.get(0));
		System.out.println(load.get(1));
		System.out.println(load.get(2));
		// OR
		load.stream().forEach(e -> System.out.println(e));