I'm writing a Java program to capture the output of a terminal command. Under "normal" conditions, i.e. where I execute the command directly into the terminal myself, I can see the following result:
However, the output rendered by my Java program only captures a small subset of that, see here:
This is the codebase I'm speaking of:
import java.io.*;
class evmTest {
public static void main(String[] args) {
String evmResult = "";
String evmCommand = "evm --debug --code 7f00000000000000000000000000000000000000000000000000000000000000027f00000000000000000000000000000000000000000000000000000000000000027f00000000000000000000000000000000000000000000000000000000000000020101 run";
try {
Runtime r = Runtime.getRuntime();
Process p = r.exec(evmCommand);
BufferedReader in = new BufferedReader(new
InputStreamReader(p.getInputStream()));
String inputLine;
while ((inputLine = in.readLine()) != null) {
System.out.println(inputLine);
evmResult += inputLine;
}
in.close();
} catch (IOException e) {
System.out.println(e);
}
}
}
Thus far I've not been able to determine why that code is only able to emit the paltry 0x. I've posted this question in the hopes that someone might be able to help me track down the cause of this error.
do it like this:
import java.io.*;
class evmTest {
public static void main(String[] args) {
String evmResult = "";
String evmCommand = "evm --debug --code 7f00000000000000000000000000000000000000000000000000000000000000027f00000000000000000000000000000000000000000000000000000000000000027f00000000000000000000000000000000000000000000000000000000000000020101 run";
try {
Runtime rt = Runtime.getRuntime();
String command = "evm --debug --code 7f00000000000000000000000000000000000000000000000000000000000000027f00000000000000000000000000000000000000000000000000000000000000027f00000000000000000000000000000000000000000000000000000000000000020101 run";
Process proc = rt.exec(command);
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);
}
} catch (IOException e) {
System.out.println(e);
}
}
}
Related
I have made a cross compiler using gcc. Now I want the compile and run commands to be executed in a terminal through java program. Here is the code that I am using for this :
import java.io.BufferedReader;
import java.io.InputStreamReader;
public class Runterminal {
public static void main(String[] args) {
Process proc;
Process procRun;
String compileCommand = "aarch64-linux-g++ -std=c++14 test.cpp";
String runCommand = "aarch64-linux-objdump -d a.out";
try{
proc = Runtime.getRuntime().exec(compileCommand);
procRun = Runtime.getRuntime().exec(runCommand);
// Read the output
BufferedReader reader =
new BufferedReader(new InputStreamReader(proc.getInputStream()));
String line = "";
while((line = reader.readLine()) != null) {
System.out.print(line + "\n");
}
proc.waitFor();
BufferedReader readero =
new BufferedReader(new InputStreamReader(procRun.getInputStream()));
String lineo = "";
while((lineo = readero.readLine()) != null) {
System.out.print(lineo + "\n");
}
procRun.waitFor();
}
catch(Exception e)
{
System.out.println("Exception occurred "+e);
}
}
}
Now my first command is executing since I could see the a.out file being generated. The second command should dump the memory contents of file and it should print in in terminal but I am not seeing any output. Can anyone tell where I am going wrong?
I am trying to figure out how to reference a python file so that I can execute it within a Java GUI Jar. It needs to be a portable solution, so using absolute paths will not work for me. I have listed my project structure below, and have included the code for how I am trying to execute the python script..I have read things about using resources, but I have been unable to implement this successfully. I appreciate any help you can provide!
private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {
try {
Runtime rt = Runtime.getRuntime();
Process pr = rt.exec("python /scripts/script.py");
BufferedReader bfr = new BufferedReader(new InputStreamReader(pr.getInputStream()));
String line = "";
while((line = bfr.readLine()) != null)
System.out.println(line);
}
catch(Exception e) {
System.out.println(e.toString());
}
}
--OneStopShop (Project)
--Source Packages
--images
--onestopshop
--Home.java
--scripts
--script.py
Starting a file path with a / means you want to start at the root of your file system.
Your code worked for me by simply removing that leading slash:
public static void main(String[] args) {
try {
File python = new File("scripts/script.py");
System.out.println(python.exists()); // true
Runtime rt = Runtime.getRuntime();
Process pr = rt.exec("python scripts/script.py"); // print('Hello!')
BufferedReader bfr = new BufferedReader(new InputStreamReader(pr.getInputStream()));
String line = "";
while((line = bfr.readLine()) != null)
System.out.println(line);
}
catch(Exception e) {
System.out.println(e.toString());
}
}
// true
// Hello!
// Process finished with exit code 0
The reason why putting a wrong file did not show an error is because this java code only displays the input stream (getInputStream()), not the error stream (getErrorStream()):
public static void main(String[] args) {
try {
Runtime rt = Runtime.getRuntime();
Process pr = rt.exec("python scripts/doesnotexist.py");
BufferedReader bfr = new BufferedReader(new InputStreamReader(pr.getErrorStream()));
String line = "";
while((line = bfr.readLine()) != null)
System.out.println(line);
}
catch(Exception e) {
System.out.println(e.toString());
}
}
// python: can't open file 'scripts/doesnotexist.py': [Errno 2] No such file or directory
// Process finished with exit code 0
The following code snippet i had given is using exec function and executes hello program (simple "hello world" printing java program). But as soon as i execute the main program, print statement of instream.readline() simply returns NULL. Please try to sort out the problem. Hope the explanation is clear.
CODE:
Process process2=null;
BufferedReader inStream=null;
try
{
process2 = Runtime.getRuntime().exec("java hello");
}
catch(IOException e1)
{
System.err.println("Error on exec method");
e1.printStackTrace();
}
try
{
inStream = new BufferedReader(new InputStreamReader(process2.getInputStream() ));
System.out.println(inStream.readLine());
}
catch(IOException e1)
{
System.err.println("Error on inStream.readLine()");
e1.printStackTrace();
}
First of all your hello.java should be already compiled n the class file should present in the current directory where the program is located.
And for getting errors, you can get error stream from process class's object.
BufferedReader stdError = new BufferedReader(new InputStreamReader(pr.getErrorStream()));
String s="";
while ((s = stdError.readLine()) != null)
System.out.println(s);
Working with Eclipse/java7/windows
import java.io.BufferedReader;
import java.io.InputStreamReader;
public class ProcessDemo {
public static void main(String[] args) throws Exception {
final String dir = System.getProperty("user.dir");
System.out.println("current dir = " + dir);
Runtime run = Runtime.getRuntime();
Process pr=run.exec("javac -d "+ dir +"\\src "+ dir+"\\src\\HelloDemo.java");
pr.waitFor();
BufferedReader stdError = new BufferedReader(new InputStreamReader(pr.getErrorStream()));
BufferedReader buf = new BufferedReader(new InputStreamReader(pr.getInputStream()));
String line = "";
String 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 output
while ((line=buf.readLine()) != null)
System.out.println(line);
pr.destroy();
Runtime run1 = Runtime.getRuntime();
Process pr1=run1.exec("java -cp "+dir+"\\src HelloDemo");
BufferedReader stdError1 = new BufferedReader(new InputStreamReader(pr1.getErrorStream()));
BufferedReader buf1 = new BufferedReader(new InputStreamReader(pr1.getInputStream()));
//interpretting file n executing it line by line :D :P
pr1.waitFor();
String temp;
// read any errors from the attempted command
System.out.println("\n\nHere is the standard error of the command (if any):\n");
while ((temp = stdError1.readLine()) != null)
System.out.println(temp);
//read output
System.out.println(buf1.readLine());
while ((temp=buf1.readLine()) != null)
System.out.println(temp);
}
}
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().
I want to execute dos based external command through java program if there there is any way please help me
String[] options = new String[]{"option1", "option2"};
Runtime.getRuntime().exec("command", options);
The following bit of code will run the dir command, and then print out for you as well as error. Taken and adapted from (http://www.devdaily.com/java/edu/pj/pj010016)
import java.io.*;
public class JavaRunCommand {
public static void main(String args[]) {
String s = null;
try {
// run the Windows command (dir)
// using the Runtime exec method:
Process p = Runtime.getRuntime().exec("dir");
BufferedReader stdInput = new BufferedReader(new
InputStreamReader(p.getInputStream()));
BufferedReader stdError = new BufferedReader(new
InputStreamReader(p.getErrorStream()));
// read the output from the command
System.out.println("Here is the standard output of the command:\n");
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);
}
System.exit(0);
}
catch (IOException e) {
System.out.println("exception happened
- here's what I know: ");
e.printStackTrace();
System.exit(-1);
}
} }