Calling Java app with "subprocess" from Python and reading the Java app output

Question

What is the nicest way to read the output (i.e. via System.out.println) of a Java app which is called from Python with

subprocess.Popen("java MyClass", shell=True)

without writing and reading a file? (Using Jython etc is not a possible solution)

sidenote: prefer the syntax given by S. Mark below when using subprocess.Popen (i.e. the list for the first argument, and the default value for shell (False). See logilab.org/blogentry/20469 for more on this. — gurney alex
– gurney alex, Commented Mar 5, 2010 at 17:12

YOU · Accepted Answer · 2010-03-05 16:56:15Z

5

p1 = subprocess.Popen(["/usr/bin/java", "MyClass"], stdout=subprocess.PIPE)
print p1.stdout.read()

answered Mar 5, 2010 at 16:56

YOU

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1 Comment

Use Popen.communicate() to perform a blocking read until popened process terminates.

Sney · Accepted Answer · 2010-03-05 16:59:47Z

3

I just found the solution:

p = subprocess.Popen("java MyClass",
          shell=True,
          stdout=subprocess.PIPE)
output, errors = p.communicate()

S.Mark's is fine too!

answered Mar 5, 2010 at 16:59

Sney

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I was unable to call javac src/*.java by passing a list to Popen due to the wildcard, not sure why. Giving a string and using communicate() works