getting the process ID from inside UNIX. (echo problem)

[Ferman]

Hi,


I found a solution. I run a command by exec() on UNIX OS.

program part like this;
try
{
String vCommand({"echo", "$$"});
Process p = Runtime.getRuntime().exec(vCommand);
BufferedReader br =
new BufferedReader(new InputStreamReader(p.getInputStream()));
int pid = Integer.parseInt(br.readLine());
System.out.println(pid);
p.destroy();
p = null;
br = null;
}
catch (java.io.IOException e)
{
System.out.println(e);
}

But it is give me "$$" characters. I didn't obtain the process id. What is
the problem ?
OS: SunOS

 

[Joona I Palaste]

Hi,

I found a solution. I run a command by exec() on UNIX OS.

program part like this;
try
{
String vCommand({"echo", "$$"});
Process p = Runtime.getRuntime().exec(vCommand);
BufferedReader br =
new BufferedReader(new InputStreamReader(p.getInputStream()));
int pid = Integer.parseInt(br.readLine());
System.out.println(pid);
p.destroy();
p = null;
br = null;
}
catch (java.io.IOException e)
{
System.out.println(e);
}

But it is give me "$$" characters. I didn't obtain the process id. What is
the problem ?
OS: SunOS

The "$$" is a feature of the shell. However, processes run with
Runtime.exec() run directly on the OS, not in any shell. Therefore
your solution won't work. You could try executing a batch file that
executed "echo $$ >somefile" and then read somefile back in on the
Java side, but I'm not sure if that gets you the correct process ID.
For the really adventurous, write your own shell, which has some kind
of interface to return its process ID. Then call that interface from
Java via JNI or something.

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