Question

Using Fedora 12: mkfifo pipe creates a pipe.

When I use the following code to try to open an input stream against the named pipe it blocks on the FileInputStream constructor unless I create a writer to the pipe, such as opening another terminal and running:

tee pipe

public static void main(String[] args){
    try {
        File pipe = new File("/tmp/pipes_debugging/pipeToJava");
        System.out.println( pipe.canRead() );
        FileInputStream fis = new FileInputStream(pipe);
        System.out.println("exiting.");
    } catch (Exception e) {
        e.printStackTrace();
    }
}

Output:

true
<blocks - thread trace shown below>

Thread [main] (Suspended)   
    FileInputStream.open(String) line: not available [native method]    
    FileInputStream.<init>(File) line: 137  
    PipesDebugging.main(String[]) line: 12  

Answer 1

Copied from comments:

It seems like a correct behavior. What are you trying to do? – Banthar Jun 20 at 7:42

Yep, I think this thread might just have answered my question: stackoverflow.com/questions/2246862/… – I’m trying to read from the pipe, I was expecting the stream to open and block on read(), not block on opening the stream. – David Parks Jun 20 at 7:52