How to Run a Command At Terminal from Java Program

How to run commands you can run on terminal in Java

The existing answers give you the information on how to solve your problem in code, but they don't give a reason why your code is not working.

When you execute a program on a shell, there's significant processing done by the shell, before the program is ever executed. Your command line

    String[] command = {"ag","startTimes conf.js >> pro.txt"};
    ProcessBuilder builder = new ProcessBuilder(command);

assumes that the command ag is run with the single argument startTimes conf.js >> pro.txt - most likely not what you want to do. Let's go one step further: What if you wrote

    String[] command = {"ag","startTimes", "conf.js", ">>", "pro.txt"};
    ProcessBuilder builder = new ProcessBuilder(command);

?

This would assume that the ag command knows about the >> parameter to redirect its output - and here is where the shell comes into play: The >> operator is an instruction to the shell, telling it what to do with the output from stdout of the process. The process ag, when started by the shell, never has an idea of this redirection and has no clue about >> and the target file name at all.

With this information, just use the code samples from any of the other answers. I won't copy them into mine for proper attribution.

Executing terminal commands from java

I don't have a Linux system here to play with, but I'm pretty certain that the second command above is trying to compile Java files named "Test.java", "&&", "java" and "Test"; in other words the Runtime.exec() method treats arguments literally instead of applying shell interpretation.

You could probably get it to work with something along the lines of:

Process p = Runtime.getRuntime().exec(
    new String[] { "sh",  "-c", "javac Test.java && java Test" });

How do i run a Linux terminal cmd from a java program

You can use the below command format to run your Linux command.

Runtime r = Runtime.getRuntime();
Process p = r.exec(yourcmd);

Please go through Running unix command from Java and Unable to run Unix command in Java-Stackoverflow

Hope you get your answers here.

Run cmd commands through Java

One way to run a process from a different directory to the working directory of your Java program is to change directory and then run the process in the same command line. You can do this by getting cmd.exe to run a command line such as cd some_directory && some_program.

The following example changes to a different directory and runs dir from there. Admittedly, I could just dir that directory without needing to cd to it, but this is only an example:

import java.io.*;

public class CmdTest {
    public static void main(String[] args) throws Exception {
        ProcessBuilder builder = new ProcessBuilder(
            "cmd.exe", "/c", "cd \"C:\\Program Files\\Microsoft SQL Server\" && dir");
        builder.redirectErrorStream(true);
        Process p = builder.start();
        BufferedReader r = new BufferedReader(new InputStreamReader(p.getInputStream()));
        String line;
        while (true) {
            line = r.readLine();
            if (line == null) { break; }
            System.out.println(line);
        }
    }
}

Note also that I'm using a ProcessBuilder to run the command. Amongst other things, this allows me to redirect the process's standard error into its standard output, by calling redirectErrorStream(true). Doing so gives me only one stream to read from.

This gives me the following output on my machine:

C:\Users\Luke\StackOverflow>java CmdTest
 Volume in drive C is Windows7
 Volume Serial Number is D8F0-C934

 Directory of C:\Program Files\Microsoft SQL Server

29/07/2011  11:03    <DIR>          .
29/07/2011  11:03    <DIR>          ..
21/01/2011  20:37    <DIR>          100
21/01/2011  20:35    <DIR>          80
21/01/2011  20:35    <DIR>          90
21/01/2011  20:39    <DIR>          MSSQL10_50.SQLEXPRESS
               0 File(s)              0 bytes
               6 Dir(s)  209,496,424,448 bytes free

firing a command in terminal from java program

If you want to actually start a terminal window (rather than just executing the java process) you will need to launch xterm (or something similar) and tell xterm to run java for example

String command= "/usr/bin/xterm -e /home/raj/Desktop/java -jar test.jar"; 
Runtime rt = Runtime.getRuntime();      
Process pr = rt.exec(command);

How to execute a code n times from the terminal?

You can repeat terminal commands as mentioned in the following link.

http://www.mactricksandtips.com/2012/02/loop-repeat-terminal-commands.html

But I suggest you add a for loop and get the number of repetitions as an argument. So you can run the command the number of times you need.

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