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:
Copyimport 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
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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:
Copyimport 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
You can try this:-
CopyProcess p = Runtime.getRuntime().exec(command);
Runtime rt = Runtime.getRuntime();
Process pr = rt.exec("java -jar map.jar time.rel test.txt debug");
http://docs.oracle.com/javase/7/docs/api/java/lang/Runtime.html
You can also watch the output like this:
final Process p = Runtime.getRuntime().exec("java -jar map.jar time.rel test.txt debug");
new Thread(new Runnable() {
public void run() {
BufferedReader input = new BufferedReader(new InputStreamReader(p.getInputStream()));
String line = null;
try {
while ((line = input.readLine()) != null)
System.out.println(line);
} catch (IOException e) {
e.printStackTrace();
}
}
}).start();
p.waitFor();
And don't forget, if you are running a windows command, you need to put cmd /c in front of your command.
EDIT: And for bonus points, you can also use ProcessBuilder to pass input to a program:
String[] command = new String[] {
"choice",
"/C",
"YN",
"/M",
"\"Press Y if you're cool\""
};
String inputLine = "Y";
ProcessBuilder pb = new ProcessBuilder(command);
pb.redirectErrorStream(true);
Process p = pb.start();
BufferedReader reader = new BufferedReader(new InputStreamReader(p.getInputStream()));
BufferedWriter writer = new BufferedWriter(new OutputStreamWriter(p.getOutputStream()));
writer.write(inputLine);
writer.newLine();
writer.close();
String line;
while ((line = reader.readLine()) != null) {
System.out.println(line);
}
This will run the windows command choice /C YN /M "Press Y if you're cool" and respond with a Y. So, the output will be:
Press Y if you're cool [Y,N]?Y
I tried using the following function:
Runtime.getRuntime().exec("DIR")but it doesn't get executed and my IDE always shows the following warning:
The method exec(String) from the type Runtime is deprecated since version 18Java(67110270)
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;
}
I am new to both Java and Linux, I was trying to use some Runtime.exec() commands that would allow my program to execute commands in Linux such as cd /mnt/ and ls --group-directories-first to list files and directories contained in /mnt/ but I think I am making a problem with the execution.
I tried my code to only include the ls --group-directories-first and it worked like a charm, only problem was, it only listed subdirectories and files in the projects folder. I wanted to make my program go to /mnt/ first so I made my command line to a command array by using exec(String[] cmdarray) format as p = Runtime.getRuntime().exec(new String[]{"cd /mnt/","ls --group-directories-first"}); and when I ran it on linux, it just got executed without any error but also without any feedback/printed lines.
Here is my code:
import java.io.BufferedReader;
import java.io.InputStreamReader;
public class linCom {
public static void main(String args[]) {
String s;
Process p;
try {
p = Runtime.getRuntime().exec("ls --group-directories-first");
BufferedReader br = new BufferedReader(
new InputStreamReader(p.getInputStream()));
while ((s = br.readLine()) != null)
System.out.println("line: " + s);
p.waitFor();
System.out.println ("exit: " + p.exitValue());
p.destroy();
} catch (Exception e) {}
}
}This worked and printed out:
line: DummyFolder1
line: linCom.class
line: linCom.java
exit: 0
import java.io.BufferedReader;
import java.io.InputStreamReader;
public class linCom {
public static void main(String args[]) {
String s;
Process p;
try {
p = Runtime.getRuntime().exec(new String[]{"cd /mnt/","ls --group-directories-first"});
BufferedReader br = new BufferedReader(
new InputStreamReader(p.getInputStream()));
while ((s = br.readLine()) != null)
System.out.println("line: " + s);
p.waitFor();
System.out.println ("exit: " + p.exitValue());
p.destroy();
} catch (Exception e) {}
}
}This just got executed with no errors but also no prints on the screen.
I expected my program to just go to the /mnt/ directory and print out subdirectories and files on there, but it just got executed with no errors and no printed lines.
I have looked at other entries but could not find any answer to my problem.
I found this in forums.oracle.com
Allows the reuse of a process to execute multiple commands in Windows: http://kr.forums.oracle.com/forums/thread.jspa?messageID=9250051
You need something like
String[] command =
{
"cmd",
};
Process p = Runtime.getRuntime().exec(command);
new Thread(new SyncPipe(p.getErrorStream(), System.err)).start();
new Thread(new SyncPipe(p.getInputStream(), System.out)).start();
PrintWriter stdin = new PrintWriter(p.getOutputStream());
stdin.println("dir c:\\ /A /Q");
// write any other commands you want here
stdin.close();
int returnCode = p.waitFor();
System.out.println("Return code = " + returnCode);
SyncPipe Class:
class SyncPipe implements Runnable
{
public SyncPipe(InputStream istrm, OutputStream ostrm) {
istrm_ = istrm;
ostrm_ = ostrm;
}
public void run() {
try
{
final byte[] buffer = new byte[1024];
for (int length = 0; (length = istrm_.read(buffer)) != -1; )
{
ostrm_.write(buffer, 0, length);
}
}
catch (Exception e)
{
e.printStackTrace();
}
}
private final OutputStream ostrm_;
private final InputStream istrm_;
}
If you want to run several commands in the cmd shell then you can construct a single command like this:
rt.exec("cmd /c start cmd.exe /K \"cd c:/ && dir\"");
This page explains more.