How to invoke formatted linux shell command from Java?

Question

I'm working on the project where I've to track Disk Usage on Linux using java code.I've executed the following code

public  void checkSystemPerformance() {
    System.out.println( "------- Track Disk Usage -------" );

        BufferedReader stdInput  = null;
        BufferedReader stdError = null;
        String line = "";

        try {
            String diskUsageCommandTest = "df -h";
            //String diskUsageCommandTest = "df -h | awk '$NF==\"/\"{printf \"Disk Usage: %d/%dGB (%s)\n\", $3,$2,$5}'";I want the result of this command via java code

            Process proc = Runtime.getRuntime().exec(diskUsageCommandTest);

            stdInput  =  new BufferedReader(new InputStreamReader(proc.getInputStream()));
            stdError = new BufferedReader(new InputStreamReader(proc.getErrorStream()));

            // read the output from the command
            System.out.println("Here is the standard output of the command:\n");
            while((line = stdInput .readLine()) != null) {
                System.out.println(line);
            }

            // read any errors from the attempted command
            System.out.println("Here is the standard error of the command (if any):\n");
            while ((line = stdError.readLine()) != null) {
                System.out.println(line);
            }

            proc.waitFor();   

            } catch (Exception e) {
                e.printStackTrace();
                System.out.println(e.getMessage());
        }
    }

where I get the following output:

------- Track Memory Usage,Disk Usage and CPU Load -------
Here is the standard output of the command:

Filesystem                   Size  Used Avail Use% Mounted on
/dev/mapper/ubuntu--vg-root   19G   16G  2.3G  88% /
udev                         987M  4.0K  987M   1% /dev
tmpfs                        200M  268K  200M   1% /run
none                         5.0M     0  5.0M   0% /run/lock
none                         998M     0  998M   0% /run/shm
/dev/sda1                    236M   33M  191M  15% /boot
Here is the standard error of the command (if any):

I've executed below line via java code

String diskUsageCommandTest = "df -h | awk '$NF==\"/\"{printf \"Disk Usage: %d/%dGB (%s)\n\", $3,$2,$5}'";

where I get the following output:

------- Track Memory Usage,Disk Usage and CPU Load -------
Here is the standard output of the command:

Here is the standard error of the command (if any):

df: `|': No such file or directory
df: `awk': No such file or directory
df: `\'$NF=="/"{printf': No such file or directory
df: `"Disk': No such file or directory
df: `Usage:': No such file or directory
df: `%d/%dGB': No such file or directory
df: `(%s)': No such file or directory
df: `",': No such file or directory
df: `$3,$2,$5}\'': No such file or directory
df: no file systems processed

On the linux terminal I run the following command :

df -h | awk '$NF=="/"{printf "Disk Usage: %d/%dGB (%s)\n", $3,$2,$5}'

where I get the following output :

Disk Usage: 16/19GB (88%)

So anyone know what Can I do in the java code to get the output in format like "Disk Usage: 16/19GB (88%)"?

score 0 · Answer 1 · edited May 23 '17 at 12:24

0

you can take a look here, that would solve your problem - if it's possible in your case (create a shellscript with your commands and execute that one)

edited May 23 '17 at 12:24

Community

1
1

answered Jun 15 '16 at 06:55

Halko Karr-Sajtarevic

2,248
1
16
14

score 0 · Answer 2 · answered Jun 15 '16 at 06:59

0

Java exec expects a single command, when you provide it with all the pipes it tries to find the command named df -h | awk '$NF==\"/\"{printf \"Disk Usage: %d/%dGB (%s)\n\", $3,$2,$5}'"; which doesn't exist (try it your self in your shell, enter your command inside double quotes).

So what you need is either create a shell script with this command or execute e.g. bash -c "your command":

Process proc = Runtime.getRuntime().exec("bash", "-c", diskUsageCommandTest);

answered Jun 15 '16 at 06:59

Krzysztof Krasoń

26,515
16
89
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I added \\n instead of only \n and used Process proc = Runtime.getRuntime().exec("bash", "-c", diskUsageCommandTest);Thank you it works. – Rupali Pawar Jun 15 '16 at 07:19

SubOptimal · Answer 3 · 2016-06-15T07:44:36.257

Maybe you don't need to call a shell command for it. Have a look at the below snippet to start with.

double freeSpace = Math.round(root.getFreeSpace() / 1024D / 1024 / 1024);
double totalSpace = Math.round(root.getTotalSpace() / 1024D / 1024 / 1024);
long usedSpace = (long) (totalSpace - freeSpace);
int percentage = (int) ((usedSpace * 100) / totalSpace);
System.out.printf("Disk Usage: %d/%dGB (%d%%)%n",
        usedSpace,
        (int) totalSpace,
        percentage
);

note: The code was written as scratch. Have a look if the rounding is ok for you.

How to invoke formatted linux shell command from Java?

3 Answers3