Find the process information with top command in java

Find the process information with top command in java - java

I want to get the process information using the top command. I have the below code but it is not working, it just exists the program without any output. My goal is to get the process name, process ID, and memory usage, but that's the later part. For now, I am stuck in getting process information using the top command in Java using grep.
public void getProcessInfo(String processName) {
Runtime rt = Runtime.getRuntime();
try {
String[] cmd = { "/bin/sh", "-c", "top | grep " + processName };
Process proc = rt.exec(cmd);
InputStream stdin = proc.getInputStream();
InputStreamReader isr = new InputStreamReader(stdin);
BufferedReader br = new BufferedReader(isr);
String line = null;
while ((line = br.readLine()) != null) {
System.out.println(line);
}
} catch (Exception e) {
e.printStackTrace(e);
}
}

This question has been asked and answered many times before:
In normal mode the top command does not output to stdout, which is why you cannot simply pipe its output into another CLI utility as you try to do. Instead you have to switch the command to "batch mode" by using the -b flag. In addition you have to limit the number of iterations to a single if you want to process the result (no sense for further iterations in non interactive mode):
top -b -n 1 | grep "whatever"
This is documented on the commands man page: man top
Have fun with your project!

Runtime.exec is obsolete. Use ProcessBuilder instead.
You can make your task considerably easier by avoiding the use of grep, or any piping, altogether. Who needs grep when you have Java?
Building on arkascha's answer, you could do:
String processLine = null;
ProcessBuilder builder = new ProcessBuilder("top", "-b", "-n", "1");
Process proc = builder.start();
try (BufferedReader stdin = new BufferedReader(
new InputStreamReader(proc.getInputStream()))) {
String line;
while ((line = stdin.readLine()) != null) {
if (line.contains(processName)) { // No need for grep
processLine = line;
break;
}
}
}
You probably want to skip the summary information and header line:
String processLine = null;
ProcessBuilder builder = new ProcessBuilder("top", "-b", "-n", "1");
Process proc = builder.start();
try (BufferedReader stdin = new BufferedReader(
new InputStreamReader(proc.getInputStream()))) {
String line;
// Blank line indicates end of summary.
while ((line = stdin.readLine()) != null) {
if (line.isEmpty()) {
break;
}
}
// Skip header line.
if (line != null) {
line = stdin.readLine();
}
if (line != null) {
while ((line = stdin.readLine()) != null) {
if (line.contains(processName)) { // No need for grep
processLine = line;
break;
}
}
}
}

Related

Buffer reader adding "[?1034h" as last line when executing Linux commands in Java

I'm executing a linux command in java using processBuilder but it adds [?1034h as the last line.
It is printing all lines but after my expected last line, it adds another line with those characters.
My code:
ProcessBuilder processBuilder = new ProcessBuilder();
// -- Linux --
// Run a shell command
processBuilder.command("bash", "-c", "sudo /usr/sbin/ilorest load -f "+biossource);
try {
Process process = processBuilder.start();
output = new StringBuilder();
BufferedReader reader = new BufferedReader(
new InputStreamReader(process.getInputStream()));
String line;
while ((line = reader.readLine()) != null) {
output.append(line);
}
BufferedReader stdError = new BufferedReader(new
InputStreamReader(process.getErrorStream()));
System.out.println("Here is the standard error of the command (if any):\n");
while ((line = stdError.readLine()) != null) {
output.append(line);
System.out.println(line);
}
int exitVal = process.waitFor();
if (exitVal == 0) {
System.out.println("Success!");
System.out.println(output);
System.exit(0);
} else {
//abnormal...
}
I also wrote the output to file and even there it is showing the same.

Run system commands in java

I am a little confused about why I can't run the following command ls -l
If I run ls or pwd it works fine.
Am I missing something?
ProcessBuilder pb = new ProcessBuilder("ls -l");
pb.redirectErrorStream(true);
Process process = pb.start();
InputStream is = process.getInputStream();
InputStreamReader isr = new InputStreamReader(is);
BufferedReader br = new BufferedReader(isr);
String line;
while ( (line = br.readLine()) != null) {
System.out.println(line);
}
br.close();
One more question: How can I run multiple system commands concurrently? Using while loop or for loops will run the command one by one. Any advice?
Thanks in advance.

Change:
new ProcessBuilder("ls -l");
To:
new ProcessBuilder("ls", "-l");

String[] st = {"ls", "bin"};
ProcessBuilder pb = new ProcessBuilder(st);
pb.redirectErrorStream(true);
Process process = pb.start();
InputStream is = process.getInputStream();
InputStreamReader isr = new InputStreamReader(is);
BufferedReader br = new BufferedReader(isr);
String line;
while ( (line = br.readLine()) != null) {
System.out.println(line);
}
br.close();

Using while loop or for loops will run the command one by one.
Only when you are doing the whole start-then-read-stdout business for each one of them, one-by-one. The processes are indeed run in parallel, it's just the reading part that's stopping you from running them concurrently. All you need to do is breaking the start and read into two parts:
Stream.of(Arrays.asList("ls", "-l"),
Arrays.asList("python", "-h"),
Arrays.asList("df"))
.map(cmd->{
// Create a process for each command, but don't read the output
try {
return new AbstractMap.SimpleImmutableEntry<>(cmd,
new ProcessBuilder(cmd)
.redirectErrorStream(true)
.start().getInputStream());
} catch (IOException e) {
e.printStackTrace();
return null;
}
})
.filter(p->p!=null)
.parallel()
.forEach(in->{
// Read and print STDOUT for each process.
try (BufferedReader reader = new BufferedReader(new InputStreamReader(in.getValue()))){
String line;
while ((line = reader.readLine()) != null) {
System.out.printf("%20s: %s\n", in.getKey(), line);
}
} catch (IOException e) {
e.printStackTrace();
}
});
The parallel() call is making the output really hard to read, it's there only to demonstrate that the processes are really running concurrently.

How to execute an exe in java on eclipse and pass intput through a variable and get output on console?

I have an exe file and i want to execute it for a large number of times passing a variable as an input and print the output for each case..
Runtime runtime = Runtime.getRuntime();
for(int i=0;i<1000;i++)
{
Process p = runtime.exec("cmd /c start C:/Users/sbm/workspace/Codex/a.exe",i);
BufferedReader input = new BufferedReader(new InputStreamReader(p.getInputStream()));
String line;
while ((line = input.readLine()) != null)
{
System.out.println(line);
}
}
Even if i get the output in a file it will be helpful.

You can do something like this
for(int i=0;i<1000;i++) {
ProcessBuilder builder = new ProcessBuilder("urcmd","urarg");
builder.redirectOutput(new File("C:\\output\\process"+i+".txt"));
builder.start();
}

How to Execute Windows Commands Using Java - Change Network Settings

In Java, I want to be able to execute a Windows command.
The command in question is netsh. This will enable me to set/reset my IP address.
Note that I do not want to execute a batch file.
Instead of using a batch file, I want to execute such commands directly. Is this possible?
Here is my implemented Solution for Future Reference:
public class JavaRunCommand {
private static final String CMD =
"netsh int ip set address name = \"Local Area Connection\" source = static addr = 192.168.222.3 mask = 255.255.255.0";
public static void main(String args[]) {
try {
// Run "netsh" Windows command
Process process = Runtime.getRuntime().exec(CMD);
// Get input streams
BufferedReader stdInput = new BufferedReader(new InputStreamReader(process.getInputStream()));
BufferedReader stdError = new BufferedReader(new InputStreamReader(process.getErrorStream()));
// Read command standard output
String s;
System.out.println("Standard output: ");
while ((s = stdInput.readLine()) != null) {
System.out.println(s);
}
// Read command errors
System.out.println("Standard error: ");
while ((s = stdError.readLine()) != null) {
System.out.println(s);
}
} catch (Exception e) {
e.printStackTrace(System.err);
}
}
}

Runtime.getRuntime().exec("netsh");
See Runtime Javadoc.
EDIT: A later answer by leet suggests that this process is now deprecated. However, as per the comment by DJViking, this appears not to be the case: Java 8 documentation. The method is not deprecated.

Use ProcessBuilder
ProcessBuilder pb=new ProcessBuilder(command);
pb.redirectErrorStream(true);
Process process=pb.start();
BufferedReader inStreamReader = new BufferedReader(
new InputStreamReader(process.getInputStream()));
while(inStreamReader.readLine() != null){
//do something with commandline output.
}

You can run the command with Runtime.getRuntime().exec("<command>") (eg. Runtime.getRuntime().exec("tree")). But, this will only run executables found in path, not commands like echo, del, ... But only stuff like tree.com, netstat.com, ... To run regular commands, you will have to put cmd /c before the command (eg Runtime.getRuntime().exec("cmd /c echo echo"))

public static void main(String[] args) {
String command="netstat";
try {
Process process = Runtime.getRuntime().exec(command);
System.out.println("the output stream is "+process.getOutputStream());
BufferedReader reader=new BufferedReader( new InputStreamReader(process.getInputStream()));
String s;
while ((s = reader.readLine()) != null){
System.out.println("The inout stream is " + s);
}
} catch (IOException e) {
e.printStackTrace();
}
}
This works.

Runtime#exec().

Java Runtime.getRuntime(): getting output from executing a command line program

I'm using the runtime to run command prompt commands from my Java program. However, I'm not aware of how I can get the output the command returns.
Here is my code:
Runtime rt = Runtime.getRuntime();
String[] commands = {"system.exe", "-send" , argument};
Process proc = rt.exec(commands);
I tried doing System.out.println(proc); but that did not return anything. The execution of that command should return two numbers separated by a semicolon. How could I get this in a variable to print out?
Here is the code I'm using now:
String[] commands = {"system.exe", "-get t"};
Process proc = rt.exec(commands);
InputStream stdIn = proc.getInputStream();
InputStreamReader isr = new InputStreamReader(stdIn);
BufferedReader br = new BufferedReader(isr);
String line = null;
System.out.println("<OUTPUT>");
while ((line = br.readLine()) != null)
System.out.println(line);
System.out.println("</OUTPUT>");
int exitVal = proc.waitFor();
System.out.println("Process exitValue: " + exitVal);
But I'm not getting anything as my output, but when I run that command myself it works fine.

Here is the way to go:
Runtime rt = Runtime.getRuntime();
String[] commands = {"system.exe", "-get t"};
Process proc = rt.exec(commands);
BufferedReader stdInput = new BufferedReader(new
InputStreamReader(proc.getInputStream()));
BufferedReader 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");
String s = null;
while ((s = stdInput.readLine()) != null) {
System.out.println(s);
}
// Read any errors from the attempted command
System.out.println("Here is the standard error of the command (if any):\n");
while ((s = stdError.readLine()) != null) {
System.out.println(s);
}
Read the Javadoc for more details here. ProcessBuilder would be a good choice to use.

A quicker way is this:
public static String execCmd(String cmd) throws java.io.IOException {
java.util.Scanner s = new java.util.Scanner(Runtime.getRuntime().exec(cmd).getInputStream()).useDelimiter("\\A");
return s.hasNext() ? s.next() : "";
}
Which is basically a condensed version of this:
public static String execCmd(String cmd) throws java.io.IOException {
Process proc = Runtime.getRuntime().exec(cmd);
java.io.InputStream is = proc.getInputStream();
java.util.Scanner s = new java.util.Scanner(is).useDelimiter("\\A");
String val = "";
if (s.hasNext()) {
val = s.next();
}
else {
val = "";
}
return val;
}
I know this question is old but I am posting this answer because I think this may be quicker.
Edit (For Java 7 and above)
Need to close Streams and Scanners. Using AutoCloseable for neat code:
public static String execCmd(String cmd) {
String result = null;
try (InputStream inputStream = Runtime.getRuntime().exec(cmd).getInputStream();
Scanner s = new Scanner(inputStream).useDelimiter("\\A")) {
result = s.hasNext() ? s.next() : null;
} catch (IOException e) {
e.printStackTrace();
}
return result;
}

If use are already have Apache commons-io available on the classpath, you may use:
Process p = new ProcessBuilder("cat", "/etc/something").start();
String stderr = IOUtils.toString(p.getErrorStream(), Charset.defaultCharset());
String stdout = IOUtils.toString(p.getInputStream(), Charset.defaultCharset());

At the time of this writing, all other answers that include code may result in deadlocks.
Processes have a limited buffer for stdout and stderr output. If you don't listen to them concurrently, one of them will fill up while you are trying reading the other. For example, you could be waiting to read from stdout while the process is waiting to write to stderr. You cannot read from the stdout buffer because it is empty and the process cannot write to the stderr buffer because it is full. You are each waiting on each other forever.
Here is a possible way to read the output of a process without a risk of deadlocks:
public final class Processes
{
private static final String NEWLINE = System.getProperty("line.separator");
/**
* #param command the command to run
* #return the output of the command
* #throws IOException if an I/O error occurs
*/
public static String run(String... command) throws IOException
{
ProcessBuilder pb = new ProcessBuilder(command).redirectErrorStream(true);
Process process = pb.start();
StringBuilder result = new StringBuilder(80);
try (BufferedReader in = new BufferedReader(new InputStreamReader(process.getInputStream())))
{
while (true)
{
String line = in.readLine();
if (line == null)
break;
result.append(line).append(NEWLINE);
}
}
return result.toString();
}
/**
* Prevent construction.
*/
private Processes()
{
}
}
The key is to use ProcessBuilder.redirectErrorStream(true) which will redirect stderr into the stdout stream. This allows you to read a single stream without having to alternate between stdout and stderr. If you want to implement this manually, you will have to consume the streams in two different threads to make sure you never block.

Also we can use streams for obtain command output:
public static void main(String[] args) throws IOException {
Runtime runtime = Runtime.getRuntime();
String[] commands = {"free", "-h"};
Process process = runtime.exec(commands);
BufferedReader lineReader = new BufferedReader(new InputStreamReader(process.getInputStream()));
lineReader.lines().forEach(System.out::println);
BufferedReader errorReader = new BufferedReader(new InputStreamReader(process.getErrorStream()));
errorReader.lines().forEach(System.out::println);
}

#Senthil and #Arend answer (https://stackoverflow.com/a/5711150/2268559) mentioned ProcessBuilder. Here is the example using ProcessBuilder with specifying environment variables and working folder for the command:
ProcessBuilder pb = new ProcessBuilder("ls", "-a", "-l");
Map<String, String> env = pb.environment();
// If you want clean environment, call env.clear() first
//env.clear();
env.put("VAR1", "myValue");
env.remove("OTHERVAR");
env.put("VAR2", env.get("VAR1") + "suffix");
File workingFolder = new File("/home/user");
pb.directory(workingFolder);
Process proc = pb.start();
BufferedReader stdInput = new BufferedReader(new InputStreamReader(proc.getInputStream()));
BufferedReader 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");
String s = null;
while ((s = stdInput.readLine()) != null)
System.out.println(s);
// Read any errors from the attempted command:
System.out.println("Here is the standard error of the command (if any):\n");
while ((s = stdError.readLine()) != null)
System.out.println(s);

Create class :
public class Utils {
public static final String SHEL_EXECUTE_ERROR = "SHEL_EXECUTE_ERROR";
public static String shellExec(String cmdCommand) {
final StringBuilder stringBuilder = new StringBuilder();
try {
final Process process = Runtime.getRuntime().exec(cmdCommand);
final BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(process.getInputStream()));
String line;
while ((line = bufferedReader.readLine()) != null) {
stringBuilder.append(line);
}
} catch (Exception e) {
return SHEL_EXECUTE_ERROR;
}
return stringBuilder.toString();
}
}
and use:
final String shellExec = shellExec("cmd /c ver");
final String versionOS = shellExec.equals(SHEL_EXECUTE_ERROR) ? "empty" : shellExec;

If you write on Kotlin, you can use:
val firstProcess = ProcessBuilder("echo","hello world").start()
val firstError = firstProcess.errorStream.readBytes().decodeToString()
val firstResult = firstProcess.inputStream.readBytes().decodeToString()

Adapted from the previous answer:
public static String execCmdSync(String cmd, CmdExecResult callback) throws java.io.IOException, InterruptedException {
RLog.i(TAG, "Running command:", cmd);
Runtime rt = Runtime.getRuntime();
Process proc = rt.exec(cmd);
//String[] commands = {"system.exe", "-get t"};
BufferedReader stdInput = new BufferedReader(new InputStreamReader(proc.getInputStream()));
BufferedReader stdError = new BufferedReader(new InputStreamReader(proc.getErrorStream()));
StringBuffer stdOut = new StringBuffer();
StringBuffer errOut = new StringBuffer();
// Read the output from the command:
System.out.println("Here is the standard output of the command:\n");
String s = null;
while ((s = stdInput.readLine()) != null) {
System.out.println(s);
stdOut.append(s);
}
// Read any errors from the attempted command:
System.out.println("Here is the standard error of the command (if any):\n");
while ((s = stdError.readLine()) != null) {
System.out.println(s);
errOut.append(s);
}
if (callback == null) {
return stdInput.toString();
}
int exitVal = proc.waitFor();
callback.onComplete(exitVal == 0, exitVal, errOut.toString(), stdOut.toString(), cmd);
return stdInput.toString();
}
public interface CmdExecResult{
void onComplete(boolean success, int exitVal, String error, String output, String originalCmd);
}

Pretty much the same as other snippets on this page but just organizing things up over an function, here we go...
String str=shell_exec("ls -l");
The Class function:
public String shell_exec(String cmd)
{
String o=null;
try
{
Process p=Runtime.getRuntime().exec(cmd);
BufferedReader b=new BufferedReader(new InputStreamReader(p.getInputStream()));
String r;
while((r=b.readLine())!=null)o+=r;
}catch(Exception e){o="error";}
return o;
}

Process p = Runtime.getRuntime().exec("ping google.com");
p.getInputStream().transferTo(System.out);
p.getErrorStream().transferTo(System.out);

Try reading the InputStream of the runtime:
Runtime rt = Runtime.getRuntime();
String[] commands = {"system.exe", "-send", argument};
Process proc = rt.exec(commands);
BufferedReader br = new BufferedReader(
new InputStreamReader(proc.getInputStream()));
String line;
while ((line = br.readLine()) != null)
System.out.println(line);
You might also need to read the error stream (proc.getErrorStream()) if the process is printing error output. You can redirect the error stream to the input stream if you use ProcessBuilder.

Develop Reference

Java is a programming language and computing platform first released by Sun Microsystems in 1995.

Find the process information with top command in java - java

Related

Buffer reader adding "[?1034h" as last line when executing Linux commands in Java

Run system commands in java

How to execute an exe in java on eclipse and pass intput through a variable and get output on console?

How to Execute Windows Commands Using Java - Change Network Settings

Java Runtime.getRuntime(): getting output from executing a command line program

Categories

Resources