Question

For homework I have to read from the standard input, save it to a file and then read the file in another process. However, I’m confused as to why this code does not work:

    while((n = read(0,buf,sizeof(buf))) > 0) {
        int tempfile = open("testfile", O_TRUNC | O_CREAT, 0666);
        write ( tempfile , buf , sizeof(buf) );
        close(tempfile);
        process("testfile");
    }

I’m not supposed to use any stdio stuff.

When I look at the file I’ve created, it has 0 bytes and yet the buffer itself has the correct information….can someone help em see where I’ve gone wrong?

I can use process on file names and it correctly reads them.

Answer 1

You’ve specified O_TRUNC | O_CREAT for the open flags, but you’ve failed to specify O_RDWR or O_WRONLY.

You also probably want to write n bytes, not sizeof(buf), as the remaining sizeof(buf) - n bytes are uninitialized.