It should work fine everywhere. But be aware you're using readSync. You
should also read as much data as is available, and then do your
setTimeout().
Another option would be to clone the stdOutFd into a ReadStream and pipe()
it to process.stdout:
var stream = fs.createReadStream(null, { fd: stdOutFd, encoding: 'utf8'
});
stream.pipe(process.stdout);
Matt.
On Thu, May 9, 2013 at 5:54 AM, Benjamin Pasero
<[email protected]>wrote:
> Hi,
>
> my scenario is this: From my node application I am spawning another
> program. I want this spawned programs output piped to a file, so I pass a
> file descriptor through the options.stdio array:
>
> var stdOutFd = fs.openSync("stdout.txt", 'w+');
> var result = cw.spawn("myprogram.exe", [], { stdio: ['ignore', stdOutFd,
> 'ignore']});
>
> This works nice. Once my program has finished, I can see the output in my
> stdout.txt.
>
> Now, this is nice for short running programs, but if myprogram.exe runs
> over a minute I would like to show constant output while the program is
> running and not only at the end. So here is my question: Is it safe to
> re-use the stdOutFd from my main application and periodically read it for
> output? Something like:
>
> var stdOutFd = fs.openSync("stdout.txt", 'w+');
> var result = cw.spawn("myprogram.exe", [], { stdio: ['ignore', stdOutFd,
> 'ignore']});
>
> function readOutPut() {
> var buffer = ...
> var bytesRead = fs.readSync(stdOutFd, buffer...)
> console.log(buffer.toString());
>
> setTimeout(readOutPut, 1000); // Poll every second
> }
>
> readOutPut();
>
> I should say that this code executes fine on Windows. I would like to hear
> back from someone that has more experience if this is fragile code. An
> alternative would be to open the file a second time for reading (using "r"
> as mode since I only want to read), but I am not sure if that is actually
> needed.
>
> The reason I am worried is that I am not sure how this code would behave
> under different filesystems. Especially I am uncertain if using a UNC share
> would make a difference.
>
> Thanks,
> Ben
>
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