Running shell script from java - doesn't finish task

Question

I have a java program which is supposed to launch a shell script. The script contains 6 tasks which are to be executed in sequence. The java program launches the script and it starts(as I see the logs). But after 10-15 seconds, the execution stops, even before the first task in the shell script is completed. The strange thing is that the script runs fine when I launch it in terminal. To avoid risking the program to hang while the script is being executed, I launch it in a separate thread. What might be a probable reason?

Java code -

try {   
            log.info("run cmd - "+optionsRun);

            String[] cmdLine = (String[]) optionsRun.toArray(new     String[optionsRun.size()]);

            Process process = Runtime.getRuntime().exec(cmdLine);
            log.info("end run cmd " + this.getScriptPath());

//          
//          BufferedWriter writer = new BufferedWriter(new     OutputStreamWriter(process.getOutputStream()));
//          writer.write("mypwd");
//          writer.flush();
//          writer.close();


            InputStream is = process.getErrorStream();
            String error = inputStreamToStringValue(is);
            log.trace("Eventual error was : " + error);

            InputStream os = process.getInputStream();
        String output = inputStreamToStringValue(os);
            log.info("Eventual output was : " + output);

            if (error!=null & error.length()>0) {
                throw new ActionProcessingException("An error occurred when     running the script :'"+this.getScriptPath()+"' with following error message : "+error);    
            }else {
                log.info("Script run ended successfully.");
            }

And the shell script looks this way -

#!/bin/sh
# ./publish <path-to-publish-home-folder> <workspace_id> <start_date> <end_date>
# ./publish <path-to-publish-home-folder> 100011 2010-01-06-12:00:00-CET     2012-01-14-19:00:00-CET

rm -f $1/publish.log
echo 'Start publish' >> $1/publish.log
echo $0 $1 $2 $3 $4 $5 $6 $7 $8 $9 >> $1/publish.log

# lancement de l'export RDF du domaine
cd $1/1-export-domain
echo "Starting export domain with the command - ./export.sh $2" >> $1/publish.log
./export.sh $2

# lancement de l'export des translations du domaine
cd $1/2-export-trans
echo "Starting export domain(translated) with the command - ./export.sh $2" >>         $1/publish.log
./export.sh $2
.....
.....
a couple of more steps like 1 and 2
....

Thanks in advance,

Updated: I tried removing resource and time intensive tasks from the shell script and the execution went through. But when I try to execute tasks that take a lot of time(and resources), it doesn't complete. Is there any auto time out(or anything similar) when the shell script runs from a java program? — Ozyman
– Ozyman, Commented Dec 11, 2011 at 14:12
@AndrewFielden publish.log shows that the first task is started. And nothing else. I have separate logs for each task. After 10 or 15 seconds, the logging for the first task just stops(without the task being completed). I'm not sure if I can find any more information from the linux logs. — Ozyman
– Ozyman, Commented Dec 11, 2011 at 14:14
Difficult to answer without seeing the contents of export.sh. What does it do? — Andrew Fielden
– Andrew Fielden, Commented Dec 11, 2011 at 14:18
export.sh is a simple command line to launch a program. It looks like this java -jar -Xmx512M -Xms512M export-6.7.1-SNAPSHOT-onejar.jar -workspace $1 -output RDF -filename trans — Ozyman
– Ozyman, Commented Dec 11, 2011 at 14:26

duffymo · Accepted Answer · 2011-12-11 14:06:33Z

1

I'm not sure, but I'll recommend two links that might help you figure it out.

The first is a very old one about Runtime.exec():

http://www.javaworld.com/javaworld/jw-12-2000/jw-1229-traps.html

The second is about ProcessBuilder, the new class intended to replace Runtime.exec():

http://www.java-tips.org/java-se-tips/java.util/from-runtime.exec-to-processbuilder.html

answered Dec 11, 2011 at 14:06

duffymo

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Comments

AlexR · Accepted Answer · 2011-12-11 14:14:22Z

I cannot be sure I my guess is that the problem is in your method inputStreamToStringValue(is). It reads STDERR and it is blocking on read. When it has nothing to read from STDERR but the process is not terminated yet you will be blocked forever.

I'd recommend you to use ProcessBuilder:

    ProcessBuilder b = new ProcessBuilder();
    b.redirectErrorStream(true);

Now you can read STDIN and STDERR together.

If you still want to read them separately you have 2 solutions.

First do as you are doing now but do not be block on read, i.e. call in.available() before each call of read and then read only number of bytes that were previously available.

Second way is to use the shell redirection. Run you script and redirect its STDOUT and STDERR to temporary files. Then wait until your process terminates and then read from files. I personally think that this solution is easier and more robust.

Good luck.

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