Runtime.exec p.waitFor hangs in background mode

Hello,
I have problem while running on Solaris using java 1.4.1:
Part of the program executes shell commands like chmod +x, ... when the program is run in the foreground mode, everything works Ok, but when it runs in the background mode (using &) the program hangs at the process.waitFor() call, when I move the program to the foreground (using fg) it resumes work correctly !!!
Can any one tell me what might be going on?!!!
Thank you all in advance.

There is program-wide redirection for stdout and stderr to log the output to a log file and JTextPane, but nothing for stdin.

Similar Messages

Runtime.exec() and subprocesses

I am running a bat file through Runtime.exec(). Conetent of bat file look
likes following
E:\Progra~1\Brio\SQRServer\ORA\BINW\sqrw d:/brio/par/par_pqa.sqr
ibprod/active1@pscore -oC:/TEMP/sqr.log -printer:pd 88
d:/Brio_Reports/report1.pdf d:/brio/
exit
Now this batch file starts another executable program. That program creates
a report in a particular directory and exit the process. When I run this
file from command prompt it runs fine. But if I try same thing from
Runtime.exec(), my program hangs.
From windows process monitor tools it seems that it start a new process but
that process never ends. If I end that process forcefully then pointer
again returns to my java program.
any idea how to solve this problem.

Is there maybe any stdout or stderr (console so to say) output which is not taken care of when the thing is called from Java?

Runtime.exec() makes program act weird

Hello
I have a problem with the runtime.exec() command?
I have created a program in vb.net with a tcpClient that opens a stream to a server.
When i execute the program myself it works fine, but when i run it through my java applet with runtime.exec() its suddenly hangs reading the stream?
I can't make it work, and its so weird that the program reads the stream several times and then just hangs, even though i can see in wireshark that packets are recieved.
Please help anyone who might know how to solve this :)

Read and implement the recommendations in all sections of [When Runtime.exec() won't|http://www.javaworld.com/javaworld/jw-12-2000/jw-1229-traps.html].
db

Runtime.exec() hangs on solaris 10, deadlock in soft_delete_session ?

Hi,
In my application sometimes Runtime.exec calls hangs for ever.
The pstack of java process is at the end of the post. It seems like there is a deadlock in soft_delete_session.
Does anyone know of any java/os patch we can apply to fix this issue?
I will really appreciate any tips to get over this issue.
# uname -a
SunOS thor256 5.10 Generic_120011-14 sun4u sparc SUNW,Sun-Fire-V245
# /opt/VRTSjre/jre1.5/bin/java -version
java version "1.5.0_10"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.5.0_10-b03)
Java HotSpot(TM) Server VM (build 1.5.0_10-b03, mixed mode)
The trace is as follows:
0xff340408 __lwp_park + 0x10
0xff339068 mutex_lock_internal + 0x5d0
0xfb08a2ec soft_delete_session + 0xf0
0xfb089f90 soft_delete_all_sessions + 0x4c
0xfb084348 finalize_common + 0x70
0xfb0844d8 softtoken_fini + 0x44
0xfb0d8d48 _fini + 0x4
0xff3c00d0 call_fini + 0xc8
0xff3ca614 remove_hdl + 0xab8
0xff3c4d54 dlclose_intn + 0x98
0xff3c4e68 dlclose + 0x5c
0xfb3a2b3c pkcs11_slottable_delete + 0x138
0xfb39d664 pkcs11_fini + 0x4c
0xff2c0ea0 postforkchild_handler + 0x30
0xff332c20 fork + 0x140
0xfe8f8df4 Java_java_lang_UNIXProcess_forkAndExec + 0x7d4
0xf9226020 0xf9226020 * java.lang.UNIXProcess.forkAndExec(byte[], byte[], int, byte[], int, byte[], boolean, java.io.FileDescriptor, java.io.FileDescriptor, java.io.FileDescriptor) bci:0 (Compiled frame; information may be imprecise)
0xf92216c4 0xf92216c4 * java.lang.UNIXProcess.(byte[], byte[], int, byte[], int, byte[], boolean) bci:62 line:53 (Compiled frame)
0xf90fa6b8 0xf90fa6b8 * java.lang.ProcessImpl.start(java.lang.String[], java.util.Map, java.lang.String, boolean) bci:182 line:65 (Compiled frame)
0xf90fbe0c 0xf90fbe0c * java.lang.ProcessBuilder.start() bci:112 line:451 (Compiled frame)
0xf921842c 0xf921842c * java.lang.Runtime.exec(java.lang.String[], java.lang.String[], java.io.File) bci:16 line:591 (Compiled frame)
0xf9005874 * java.lang.Runtime.exec(java.lang.String[]) bci:4 line:464 (Interpreted frame)
0xf9005874 * TestExec.run() bci:26 line:22 (Interpreted frame)
0xf9005c2c * java.lang.Thread.run() bci:11 line:595 (Interpreted frame)
0xf9000218
0xfecdca88 void JavaCalls::call_helper(JavaValue*,methodHandle*,JavaCallArguments*,Thread*) + 0x5b8
0xfecf4310 void JavaCalls::call_virtual(JavaValue*,Handle,KlassHandle,symbolHandle,symbolHandle ,Thread*) + 0x18c
0xfecf416c void thread_entry(JavaThread*,Thread*) + 0x12c
0xfecf3ff0 void JavaThread::run() + 0x1f4
0xff02fb30 void*_start(void*) + 0x200
0xff340368 lwpstart

Found this information about this problem:
Bug: http://bugs.opensolaris.org/bugdatabase/view_bug.do?bug_id=6276483
Info for patch 127111-11: http://sunsolve.sun.com/search/document.do?assetkey=1-21-127111-11-1
Download page: http://sunsolve.sun.com/show.do?target=patches/zos-s10

Runtime.exec() hangs with 1.4.1

Hello altogether,
I am trying to execute a command with Runtime.getRuntime.exec()
I have already taken care of capturing the output and I observe that depending of the program I try to execute the process hangs.
I am using JRE 1.4.1_02 under Redhat 7.2 with kernel 2.4.18-26
Executing the same program under JRE 1.3.1 the program does not hang.
Executing 'top -bn0q' hangs, executing 'ls -als' it hangs.
Here is my sample code:
<code>
import java.io.*;
public class Exec
/** catches the output in a parallel thread */
class StreamReader extends Thread
String category = null;
InputStream is;
StreamReader(String category, InputStream is)
this.category = category;
this.is = is;
public void run()
try
System.out.println(this.category+": reader runs");
InputStreamReader isr = new InputStreamReader(this.is);
BufferedReader br = new BufferedReader(isr);
String line = null;
while (br.ready() && (line = br.readLine())!=null)
System.out.println(this.category+':'+line);
catch (Exception e)
e.printStackTrace();
public void run(String[] cmd)
StringBuffer outStrBuf = new StringBuffer();
try
Runtime rt = Runtime.getRuntime();
System.out.println("got runtime");
Process process = rt.exec(cmd);
System.out.println("fired cmd");
// any errors
System.out.println("prepare error stream");
StreamReader errSr = new StreamReader("ERR",process.getErrorStream());
// any output
System.out.println("prepare output stream");
StreamReader outSr = new StreamReader("OUT",process.getInputStream());
// start the readers to read
System.out.println("start readers");
errSr.start();
outSr.start();
System.out.println("waiting for process to end");
process.waitFor(); //Waits for the subprocess to complete.
catch (Exception e)
System.err.println("Error while executing cmd: " + cmd);
e.printStackTrace();
System.out.println(outStrBuf);
     public static void main(String[] args)
String [] cmd = {"top","-bn0q"};
if (args.length >= 1)
cmd = args;
System.out.println(args[0]);
Exec exec = new Exec();
exec.run(cmd);
</code>
The output of java Exec is:
[user]$ java Exec
got runtime
fired cmd
prepare error stream
prepare output stream
start readers
waiting for process to end
OUT: reader runs
ERR: reader runs
...and there it hangs. Interesting is, that when I use ls -als as command, I get the directory listing.
Do you have any ideas what I am doing wrong? Is there any difference in the Runtime.exec() between 1.3 and 1.4 version?

Unbelievable and what a shame. I was hacking 2 days on several variations of this problem and the solution and I finally found one difference:
while (br.ready() && (line = br.readLine())!=null)
I assume that when executing the command, the output streams are not ready and my Output gobbler threads end.
...however the command is still executing and starts to write its output. And as we all know this will overflow the buffer and the process hangs.
So the final solution is:
/** catches the output in a parallel thread */
class StreamReader extends Thread
String category = null;
InputStream is;
StreamReader(String category, InputStream is)
    this.category = category;
    this.is = is;
public void run()
    try
      System.out.println(this.category+": reader runs");
      InputStreamReader isr = new InputStreamReader(this.is);
      BufferedReader br = new BufferedReader(isr);
      String line = null;
      while (/**br.ready() &&*/ (line = br.readLine())!=null)
        System.out.println(this.category+':'+line);
    catch (Exception e)
      e.printStackTrace();
}So the only question that I have open: Why does this makes no problem with 1.3 but with 1.4 ?

Running java process in a while loop using Runtime.exec() hangs on solaris

I'm writting a multithreaded application in which I'll be starting multiple instances of "AppStartThread" class (given below). If I start only one instance of "AppStartThread", it is working fine. But if I start more than one instance of "AppStartThread", one of the threads hangs after some time (occasionaly). But other threads are working fine.
I have the following questions:
1. Is there any problem with starting a Thread inside another thread?. Here I'm executing the process in a while loop.
2. Other thing i noticed is the Thread is hanging after completing the process ("java ExecuteProcess"). But the P.waitFor() is not coming out.
3. Is it bcoz of the same problem as given in Bug ID : 4098442 ?.
4. Also java 1.2.2 documentation says:
"Because some native platforms only provide limited buffer size for standard input and output streams, failure to promptly write the input stream or read the output stream of the subprocess may cause the subprocess to block, and even deadlock. "
I'm running this on sun Solaris/java 1.2.2 standard edition. If any of you have experienced the same problem please help me out.
Will the same problem can happen on java 1.2.2 enterprise edition.?
class AppStartThread implements Runnable
public void run()
while(true)
try
Process P=Runtime.getRuntime().exec("java ExecuteProcess");
P.waitFor();
System.out.println("after executing application.");
P.destroy();
P = null;
System.gc();
catch(java.io.IOException io)
System.out.println("Could not execute application - IOException " + io);
catch(java.lang.InterruptedException ip)
System.out.println("Could not execute application - InterruptedException" + ip);
catch (Exception e)
System.out.println("Could not execute application -" + e.getMessage());

I'm writting a multithreaded application in which I'll
be starting multiple instances of "AppStartThread"
class (given below). If I start only one instance of
"AppStartThread", it is working fine. But if I start
more than one instance of "AppStartThread", one of the
threads hangs after some time (occasionaly). But other
threads are working fine.
I have the following questions:
1. Is there any problem with starting a Thread inside
another thread?. Here I'm executing the process in a
while loop.Of course this is OK, as your code is always being run by one thread or another. And no, it doesn't depend on which thread is starting threads.
2. Other thing i noticed is the Thread is hanging
after completing the process ("java ExecuteProcess").
But the P.waitFor() is not coming out.This is a vital clue. Is the process started by the Runtime.exec() actually completing or does the ps command still show that it is running?
3. Is it bcoz of the same problem as given in Bug ID :
4098442 ?.
4. Also java 1.2.2 documentation says:
"Because some native platforms only provide limited
ed buffer size for standard input and output streams,
failure to promptly write the input stream or read the
output stream of the subprocess may cause the
subprocess to block, and even deadlock. "These two are really the same thing (4098442 is not really a bug due to the reasons explained in the doc). If the program that you are exec'ing produces very much output, it is possible that the buffers to stdout and stderr are filling preventing your program from continuing. On Windows platforms, this buffer size is quite small (hundreds of characters) while (if I recall) on Solaris it is somewhat larger. However, I have seent his behavior causing problem on Solaris 8 in my own systems.
I once hit this problem when I was 'sure' that I was emitting no output due to an exception being thrown that I wasn't even aware of - the stack trace was more than enough to fill the output buffer and cause the deadlock.
You have several options. One, you could replace the System.out and System.err with PrintStream's backed up by (ie. on top of) BufferedOutputStream's that have large buffers (multi-K) that in turn are backed up by the original out and err PrintStream's. You would use System.setErr() and System.setOut() very early (static initializer block) in the startup of your class. The problem is that you are still at the mercy of code that may call flush() on these streams. I suppose you could implement your own FilterOutputStream to eat any flush requests...
Another solution if you just don't care about the output is to replace System.out and System.err with PrintStreams that write to /dev/nul. This is really easy and efficient.
The other tried and true approach is to start two threads in the main process each time you start a process. These will simply consume anything that is emitted through the stdout and stderr pipes. These would die when the streams close (i.e. when the process exits). Not pretty, but it works. I'd be worried about the overhead of two additional threads per external process except that processes have such huge overhead (considering you are starting a JVM) that it just won't matter. And it's not like the CPU is going to get hit much.
If you do this frequently in your program you might consider using a worker thread pool (see Doug Lea's Executor class) to avoid creating a lot of fairly short-lived threads. But this is probably over-optimizing.
Chuck

Runtime.exec() causes app to hang

Hello all, I'm having an issue with the Runtime.exec() and I'm hoping someone in the forum can shed some light on it for me.
My application currently includes the capability for my end users to run a variety of reports, all of which are written in SQR (BRIO reporting language). Since my application is in Java ( and all the reports were written for a previous application), I use the Runtime.exec() call to launch the SQR viewer application. The problem I'm having is this: When I run the code below in my development environment (using a front end framework from Oracle (JDeveloper)), everything works fine. When I deploy my application to a jar file, the application runs fine until the code below is called. At this point the application hangs terribly and my CPU usage is maxed out by my app. The process for the report is created but is unable to garner the necessary resources to run because my application is using them all. If I kill my application, the report process then runs as expected.
Why would the same code run fine in development but not when deployed to a jar file?
The following is the code in question:
    try {
      Runtime rt = Runtime.getRuntime();
      Process proc = rt.exec(sDrive + "\\SQR6\\SQRW " + sDrive + "\\SQR6\\REPORTS\\" + repName + ".SQT " + sConn + " -RT -FC:\\SPL\\ -C -ZIV");
      InputStream stderr = proc.getErrorStream();
      InputStreamReader isr = new InputStreamReader(stderr);
      BufferedReader br = new BufferedReader(isr);
      String line = null;
      while ( (line = br.readLine()) != null)
        System.out.println(line);
      int exitVal = proc.waitFor();
    catch (Throwable ie)
      ie.printStackTrace();
    }    All thoughts and suggestions are welcomed.
Thanx in advance,
eribs4e

So you either tried adding a reader for stdout, or you're sure that nothing is produced on stdout? And you're sure it's not expecting anything on stdin?
You say your app runs fine up to that code, and then eats all the CPU right? Sounds like a spin lock. One possibility is that it's something like this: br = bufferedReaderForStdOut;
while ( (line = br.readLine()) != null)
        System.out.println(line);
while ((line = br.readLine() == null); Not that I expect that you have precisely that in your code, but I suspect the problem may actually be a spin-lock that precedes the code you've posted. I don't see anything obviously wrong with what you have, so if there's a problem in your code, it's probably in what you haven't shown.

Runtime.exec() + getOutputStream() +write+me program=hang

I'm trying to write to the standard input of an external prorgram by using Runtime.exec() and writing to the outputstream of the process it creates. I write to the standard in and then wait for that process to finish using waitFor() but it just hangs there. Is there something special to do before writing the data?
There is nothing funky about my code, it's just basic stuff.
OutputStream out =process.getOutputStream();
out.write(data);
out.flush();
out.close();
process.wairFor();

Do you really know
1. That the process got the data and processed it?
2. That the process exited and you are still hanging?
Sorry if I'm just stating the obvious, but is the other process perhaps waiting for an end-of-line or end-of-input?
Finally, you didn't say what the other process technology is, but I've had some surprises when attempting to work between java and other technologies. Example: Other process was LEX, which uses a Windows flag to check for character or block input. Flag was set in a surprising manner when java was the source, and my LEX blocked forever.

Problem with runtime.exec().It hangs Up

Hi all,
I am having a problem with the runtime.exec method.I am trying to execute linux commands using this method.For most of the commands it works fine.But when i tried to change the user with the su command in linux my program hung up.So please help me to get around this.any help would be highly appreciable..
I am pasting the code..
<code>
Process p=null;
int ch=0;
try
System.out.println("Before executing command");
String unlock_command="sh changeuser.sh";
p = Runtime.getRuntime().exec(new String[] {"/bin/sh","-c","su tony"});
InputStreamReader myIStreamReader = new InputStreamReader(p.getInputStream());
while ((ch = myIStreamReader.read()) != -1)
System.out.print((char)ch);
p.waitFor();
int p_exitvalue = p.exitValue();
System.out.println("After executing the command and the exit value = "+p_exitvalue);
p.destroy();
catch (IOException anIOException)
System.out.println(anIOException);
catch(Exception e)
e.printStackTrace();
</code>
Thanks
HowRYou

Hi sabre,
What you have pointed out is right.But if i change the user as root then it will not ask for a password.Isn't it.Anyway thank you for giving your suggestions.Can yoiu help me more.Waiting for all of your help.I will try to swoitch between different users othere than root by giving the password.So just help me.

Runtime.exec hang

I used Runtime class to run a 3rd party exe. If I just called
Runtime.exec("3rd.exe whatever"), 3rd.exe would run half way
then hang. If I called Runtime.exec("start 3rd.exe whatever"),
3rd.exe would run successfully. However, Runtime.getInputStream
couldn't receive the output from 3rd.exe.
Is any way I can get the output from 3rd.exe with "start 3rd.exe
whatever"?

Hi,KellanMom :
I also experienced this problem.
You should read sth from Process's inputStream,
outputStream and errorStream.
You can browse "http://www.javaworld.com/javaworld/jw-12-2000/jw-1229-traps.html" to get details.
Regards.
Sunway

Runtime.exec hangs even If I drain output.

Hi Everyone,
I'm trying to make a program that would give me access to a command line on a remote server. So what I'm trying to do is use Runtime.exec("cmd") to open a command line, then reading from it and printing to it normally.
The problem is the same very common problem anyone using exec encounters: it hangs. The thing is, however, I do drain the input and error streams immediately, but it still hangs, and here's a curious thing:
When I use a BufferedReader and use its readLine() method, it only manages to read the first two lines before it hangs, giving me an output such as this:
+Microsoft Windows XP [Version 5.1.2600]+
+(C) Copyright 1985-2001 Microsoft Corp.+
Of course I placed the System.out.println inside the loop that reads lines, cause if I put it outside the loop, I don't get any output at all because the subprocess hangs before the loop is finished.
Now if I don't use a buffer, and use the input's stream's read() method, it reads all the way through the output, but hangs at the end where it's supposed to read -1, and never reads it.
I thought maybe I could bypass that, and break the loop at the last character in the output (the character '>'). Now while this works the first time, sending the output to the client like this:
+Microsoft Windows XP [Version 5.1.2600]+
+(C) Copyright 1985-2001 Microsoft Corp.+
F:\eclipse workspace\RemCommand>
However it doesn't work after that, when I try to type any command. I send my command to the subprocess normally using a PrintWriter, and then try to read the output, but that fails because apparently the subprocess is still stuck at the -1 from the previous read operation.
I really don't know what the problem is, is it possible that the read possibly doesn't return -1 at all, maybe returns a different character to signify the end or something, and my loop keeps trying to read or what?
I'm at my wits end.
Any help?
Thanks in advance.

Here is the code again. Check the somehow improved detection of the default Windows prompt.
Check the lines in comments that allow you to define your own, perhaps more reliable prompt.
import java.io.*;
import java.util.*;
public class Cmd
public static void main( String[] args ) throws Exception
    ProcessBuilder pb = new ProcessBuilder( "cmd" );
//    Map<String, String> env = pb.environment();
//    env.put( "PROMPT", ".,.,." );
    pb.redirectErrorStream( true );
    Process p = pb.start();
    InputStream is = p.getInputStream();
    OutputStream os = p.getOutputStream();
    PrintWriter pw = new PrintWriter( os, true );
    readToPrompt( is );
    pw.println( "dir" );
    readToPrompt( is );
    pw.println( "ipconfig" );
    readToPrompt( is );
    pw.println( "netstat" );
    readToPrompt( is );
private static void readToPrompt( InputStream is ) throws IOException
    String s = "";
    for (;;)
      int i = is.read();
      if ( i < 0 )
        System.out.println();
        System.out.println( "EOF" );
        System.exit( 0 );
      s += new String( new byte[] { ( byte )i } ).charAt( 0 );
      if ( s.endsWith( "\r\n" ) )
        System.out.print( s );
        s = "";
//      if ( s.equals( ".,.,." ) )
      if ( s.length() > 2 && s.charAt( 0 ) >= 'A' && s.charAt( 0 ) <= 'Z' && s.charAt( 1 ) == ':' && s.endsWith( ">" ) )
        System.out.print( s );
        break;
}Edited by: baftos on Sep 10, 2008 11:27 AM

Backgrounding Runtime.exec

Is there a way to background a Runtime.exec() call to a batch file? What I want to do is right after the batch file is executed I want to exit java and keep the .bat process running in the background. I am creating a process that lets the user upgrade a local JVM in the directory. But you can't necessarily do that from java. So I have a .bat file that extracts the necessary files. Any suggestions on how to background that?

Hmmm as far as i know the Process created by Runtime.getRuntime.exec(String ex), runs independantly of the creator. And that is also what i get from reading the Process API, espacially this part "The subprocess is not killed when there are no more references to the Process object, but rather the subprocess continues executing asynchronously":
API BEGIN
The Runtime.exec methods create a native process and return an instance of a subclass of Process that can be used to control the process and obtain information about it. The class Process provides methods for performing input from the process, performing output to the process, waiting for the process to complete, checking the exit status of the process, and destroying (killing) the process.
The Runtime.exec methods may not work well for special processes on certain native platforms, such as native windowing processes, daemon processes, Win16/DOS processes on Microsoft Windows, or shell scripts. The created subprocess does not have its own terminal or console. All its standard io (i.e. stdin, stdout, stderr) operations will be redirected to the parent process through three streams (Process.getOutputStream(), Process.getInputStream(), Process.getErrorStream()). The parent process uses these streams to feed input to and get output from the subprocess. Because some native platforms only provide limited buffer size for standard input and output streams, failure to promptly write the input stream or read the output stream of the subprocess may cause the subprocess to block, and even deadlock.
The subprocess is not killed when there are no more references to the Process object, but rather the subprocess continues executing asynchronously.
There is no requirement that a process represented by a Process object execute asynchronously or concurrently with respect to the Java process that owns the Process object.
API END
Poul Krogh

Runtime.exec and ServerSocket for IPC...blocking problems

I have built an IDE for assembling/deploying web applications.
I am supporting a 'test' mode in the IDE where a compiled 'solution/application' is executed in a separate vm from the IDE using Runtime.exec. For the whole sandbox thing. Don't want a wayward application crashing my IDE.
Naturally I want a way to communicate start/stop from the IDE to the running application. So sockets are my only choice. Calling process.destroy from my IDE won't invoke a shutdownhandler in the generated application's vm, and I want an orderly shutdown as the generated applications open resources/etc.
When I execute the generated application from within the IDE the thread code that creates a server socket blocks in the ServerSocket constructor...why?
When I execute the solution using 'java' outside of my IDE, I can set up a server socket and all works fine.
My IDE is NEVER creating server sockets waiting for client connects...only the generated application does this. So it isn't a case of the IDE already listening for requests on the same port as the server/generated application.
Proving the above is that I can manually start my generated application, start my ide, then invoke the menuitem from the IDE that writes a 'close' byte to the client's socket...and the running application DOES shut down.
Any ideas?

I have decided on a different approach.
At first I thought...ok I have the ServerSocket on the wrong 'side'. I then put the ServerSocket code in the always-running IDE and the Socket code on the running/exec'd application. But still a hang on the running application when constructing the Socket.
I decided instead to call Process.destroy on the running app.
Given that generated app is running in a separate vm, when it shuts down via process.destroy from the ide...although vm shutdown hooks aren't called...I guess it's ok since a destroy of the vm will release all resources. Not as clean as I'd like though.
Additionally, I cannot determine 'true' start of application as no socket notification can be done. I merely determine start after a Runtime.exec of jvm process. Subsequent errors in startup will merely be determined by the IDE in process.waitFor or process.exitValue.
I was getting a wierd socket error when attempting my prior solutions...and not a lot on the web regarding this subject...all relevant posts seemed to be in German/from Germany. Odd. Would need my wife to translate! Mein gott!
I guess I could've communicated from ide to Runtime.exec'd application via a generated file in filesystem...but this seemed cheesy. Sockets should've been used for ipc between java vms...or so I thought.

How to make Runtime.exec call Linux exec?

Howdy,
I am trying to use a combination of 'find' and 'rm' to delete all files with a certain extension in a directory and all of its subdirs.
Here's the command:
Process proc = runtime.exec("find " + dir + " -name '*.vcs' -exec rm -rf {} \\;");
It's failing, not sure why, the exitCode is 1 instead of 0. I'm not sure if it's because I have to escape the '\' character, or if it's because I am calling Linux's 'exec' function within a Java exec() call, or something else entirely.
The easiest thing to do would be to just use rm, but that doesn't seem to be an option. With rm it seems to be all or nothing -- If I try:
rm -rf *.vcs
it fails if it doesn't find a file with that extension in the start directory (even though I've specified -r). But if I enter:
rm -rf *
it nukes my directories AND files, something I don't want to happen. I realize this is a Linux thing, I'm just explaining it here as background, just in case.
Anyway, so is there a way to do this? Perhaps with another system call, without using Linux's exec()?
Many thanks
Bob

import java.io.*;
public class ExecutingALinuxCommand
    static class PipeInputStreamToOutputStream implements Runnable
        PipeInputStreamToOutputStream(InputStream is, OutputStream os)
            is_ = is;
            os_ = os;
        public void run()
            try
                byte[] buffer = new byte[1024];
                for(int count = 0; (count = is_.read(buffer)) >= 0;)
                    os_.write(buffer, 0, count);
            catch (IOException e)
                e.printStackTrace();
        private final InputStream is_;
        private final OutputStream os_;
    public static void main(String[] args)
        try
            String dir = System.getProperty("user.home") + "/work/dev";
            String[] command = {"sh","-c", "find " + dir + " -name '*.java' -exec grep -l Runtime {} \\;"};
            final Process process = Runtime.getRuntime().exec(command);
            new Thread(new PipeInputStreamToOutputStream(process.getInputStream(), System.out)).start();
            new Thread(new PipeInputStreamToOutputStream(process.getErrorStream(), System.err)).start();
            int returnCode = process.waitFor();
            System.out.println("Return code = " + returnCode);
        catch (Exception e)
            e.printStackTrace();
}

Runtime.exec() fails sometime to execute a command

Hello,
I have a program thats using Runtime.exec to execute some external programs sequence with some redirection operators.
For e.g, I have some command as follows;
1 - C:\bin\IBRSD.exe IBRSD -s
2 - C:\bin\mcstat -n @punduk444:5000#mc -l c:\ | grep -i running | grep -v grep |wc -l
3 - ping punduk444 | grep "100%" | wc -l
...etc.
These command in sequence for a single run. The test program makes multiple such runs. So my problem is sometimes the runtime.exec() fails to execute some of the commands above (typically the 2nd one). The waitFor() returns error code (-1). That is if I loop these commands for say 30 runs then in some 1~4 runs the 2nd command fails to execute and return -1 error code.
Can some one help me out to as why this is happening? Any help is appreciated
Thanks,
~jaideep
Herer is the code snippet;
Runtime runtime = Runtime.getRuntime();
//create process object to handle result
Process process = null;
commandToRun = "cmd /c " + command;
process = runtime.exec( commandToRun );
CommandOutputReader cmdError = new CommandOutputReader(process.getErrorStream());
CommandOutputReader cmdOutput = new CommandOutputReader(process.getInputStream());
cmdError.start();
cmdOutput.start();
CheckProcess chkProcess = new CheckProcess(process);
chkProcess.start();
int retValue = process.waitFor();
if(retValue != 0)
return -1;
output = cmdOutput.getOutputData();
cmdError = null;
cmdOutput = null;
chkProcess = null;
/*******************************supporting CommandOutputReader class *********************************/
public class CommandOutputReader extends Thread
private transient InputStream inputStream; //to get output of any command
private transient String output; //output will store command output
protected boolean isDone;
public CommandOutputReader()
super();
output = "";
this.inputStream = null;
public CommandOutputReader(InputStream stream)
super();
output = "";
this.inputStream = stream;
public void setStream(InputStream stream)
this.inputStream = stream;
public String getOutputData()
return output;
public void run()
if(inputStream != null)
final BufferedReader bufferReader = new BufferedReader(new InputStreamReader(inputStream), 1024 * 128);
String line = null;
try
while ( (line = bufferReader.readLine()) != null)
if (ResourceString.getLocale() != null)
Utility.log(Level.DEBUG,line);
//output += line + System.getProperty(Constants.ALL_NEWLINE_GETPROPERTY_PARAM);
output += line + "\r\n";
System.out.println("<< "+ this.getId() + " >>" + output );
System.out.println("<< "+ this.getId() + " >>" + "closed the i/p stream...");
inputStream.close();
bufferReader.close();
catch (IOException objIOException)
if (ResourceString.getLocale() != null)
Utility.log(Level.ERROR, ResourceString.getString("io_exeception_reading_cmd_output")+
objIOException.getMessage());
output = ResourceString.getString("io_exeception_reading_cmd_output");
else
output = "io exeception reading cmd output";
finally {
isDone = true;
public boolean isDone() {
return isDone;
/*******************************supporting CommandOutputReader class *********************************/
/*******************************supporting process controller class *********************************/
public class CheckProcess extends Thread
private transient Process monitoredProcess;
private transient boolean continueLoop ;
private transient long maxWait = Constants.WAIT_PERIOD;
public CheckProcess(Process monitoredProcess)
super();
this.monitoredProcess = monitoredProcess;
continueLoop =true;
public void setMaxWait(final long max)
this.maxWait = max;
public void stopProcess()
continueLoop=false;
public void run()
//long start1 = java.util.Calendar.getInstance().getTimeInMillis();
final long start1 = System.currentTimeMillis();
while (true && continueLoop)
// after maxWait millis, stops monitoredProcess and return
if (System.currentTimeMillis() - start1 > maxWait)
if(monitoredProcess != null)
monitoredProcess.destroy();
//available for garbage collection
// @PMD:REVIEWED:NullAssignment: by jbarde on 9/28/06 7:29 PM
monitoredProcess = null;
return;
try
sleep(1000);
catch (InterruptedException e)
if (ResourceString.getLocale() != null)
Utility.log(Level.ERROR, ResourceString.getString("exception_in_sleep") + e.getLocalizedMessage());
System.out.println(ResourceString.getString("exception_in_sleep") + e.getLocalizedMessage());
else
System.out.println("Exception in sleep" + e.getLocalizedMessage());
if(monitoredProcess != null)
monitoredProcess.destroy();
//available for garbage collection
// @PMD:REVIEWED:NullAssignment: by jbarde on 9/28/06 7:29 PM
monitoredProcess = null;
/*******************************supporting process controller class *********************************/

Hi,
Infact the command passed to the exec() is in the form of a batch file, which contains on of these commands. I can not put all commands in one batch file due to inherent nature of the program.
But my main concern was that, why would it behave like this. If I run the same command for 30 times 1~3 times the same command can not be executed (returns with error code 1, on wiun2k pro) and rest times it works perfectly fine.
Do you see any abnormality in the code.
I ahve used the same sequence of code as in the article suggested by
"masijade". i.e having threads to monitor the process and other threads to read and empty out the input and error streams so that the buffer does not get full.
But I see here the problem is not of process getting hanged, I sense this because my waitFor() returns with error code as 1, had the process hanged it would not have returned , am I making sense?
Regards,
~jaideep

Runtime.exec p.waitFor hangs in background mode

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