exec with stdin stdout

[Guest]

Why this code not working?


byte[] buf = new byte[10000];
Process p = Runtime.getRuntime().exec("php -n 1.php");
p.getErrorStream().close();
InputStream is = p.getInputStream();
OutputStream os = p.getOutputStream();
os.write("write serialized data...".getBytes());// never takes data
p.waitFor();
int count = is.read(buf); // count == -1
System.out.println(buf); // write garbage
System.exit(0);

 

[Guest]

Why this code not working?

byte[] buf = new byte[10000];
Process p = Runtime.getRuntime().exec("php -n 1.php");
p.getErrorStream().close();
InputStream is = p.getInputStream();
OutputStream os = p.getOutputStream();
os.write("write serialized data...".getBytes());// never takes data
p.waitFor();
int count = is.read(buf); // count == -1
System.out.println(buf); // write garbage
System.exit(0);

So! it works now! The output comes to ErrorStream (from my error)
I correct the problem and the output comes to InputStream.

But the
os.write("write serialized data...".getBytes());
never gives the data to child process.
Why?

 

[Andrew Thompson]

So! it works now!

Aaah.. There you go - not lazy, just resting. ;-)

--
Andrew Thompson
physci.org 1point1c.org javasaver.com lensescapes.com athompson.info
"..my time is all used up, just to sit around creatin¢ all that groovy kind
of stuff."
Spencer Davis Group 'I'm A Man'

 

[Roedy Green]

Process p = Runtime.getRuntime().exec("php -n 1.php");
p.getErrorStream().close();
InputStream is = p.getInputStream();
OutputStream os = p.getOutputStream();
os.write("write serialized data...".getBytes());// never takes data
p.waitFor();

What does the spawned program do? If it writes first, it is sitting
waiting for you to accept those bytes before it will read the ones you
are sending it, in a Mexican standoff.

Either you need to choreograph the dance carefully, or use separate
threads to read and write.

 

[Roedy Green]

os.write("write serialized data...".getBytes());// never takes data

I trust this spawned C program is reading 8-bit chars from the console
in the default character encoding, and is not waiting for a \n or the
like.

It is surely not reading Java serialised data. Only Java could make
head nor tail of that.

For more hints see http://mindprod.com/jgloss/exec.html