Executing Unix Command Through Java

[Aulia Yusuf]

Hi,

I am trying to run some unix command through:

Runtime.getRuntime().exec("some unix command line");

I am running the code on Linux platform. However, I always got some errors. Here are the stack trace of them:

java.io.IOException: Cannot allocate memory
java.io.IOException: java.io.IOException: Cannot allocate memory
at java.lang.UNIXProcess.<init>(UNIXProcess.java:148)
at java.lang.ProcessImpl.start(ProcessImpl.java:65)
at java.lang.ProcessBuilder.start(ProcessBuilder.java:451)
at java.lang.Runtime.exec(Runtime.java:591)
at java.lang.Runtime.exec(Runtime.java:429)
at java.lang.Runtime.exec(Runtime.java:326)



Anybody has any idea why is this happening? Thanks.
Aulia

[Ajay Singh]

You can try using ssh library of java (like http://javassh.org/) to connect to the remote server and read the log file and process it. I don't think you can fork a process remotely otherwise.

[Aulia Yusuf]

No, I am locally executing the command. In addition to that, I cannot even execute something simple like "ls". I am also doing it in a tight loop, but each loop throws the exception.

The code looks like this:

public boolean executeCommand() {
boolean success = true;
for (int i = 0; i < 5; i++) {
Process p = null;
try {
p = Runtime
.getRuntime()
.exec("ls");
 
InputStreamReader inR = new InputStreamReader(p
.getErrorStream());
 
BufferedReader buf = new BufferedReader(inR);
String line;
while ((line = buf.readLine()) != null) {
System.out.println(line);
}

p.destroy();
} catch (Exception e) {
System.err.println(e.getMessage());
e.printStackTrace();
success = false;
 
} finally {
 
p = null;
}
}
 
return success;
 
}

Please let me know if anyone has ideas why such simple code like this throws the Exception. Thanks.

[Ajay Singh]

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