On Wednesday, 17 February 2021 at 14:36:58 UTC, Steven
Schveighoffer wrote:
On 2/17/21 1:58 AM, Jedi wrote:
I an using pipeShell, I have redirected stdout, stderr, and
stdin.
I am trying to read from the output and display it in my app.
I have followed this code almost exactly except I use try wait
and flush because the app is continuously updating the output.
(it outputs a progress text on the same line and I'm trying to
poll it to report to the user)
auto pipes = pipeProcess("my_application", Redirect.stdout |
Redirect.stderr);
scope(exit) wait(pipes.pid);
// Store lines of output.
string[] output;
foreach (line; pipes.stdout.byLine) output ~= line.idup;
// Store lines of errors.
string[] errors;
foreach (line; pipes.stderr.byLine) errors ~= line.idup;
My code
auto p = pipeShell(`app.exe "`~f.name~`"`, Redirect.stdout |
Redirect.stdin | Redirect.stderr);
while(!tryWait(p.pid).terminated)
{
string[] output;
foreach (line; p.stdout.byLine)
You need to be careful here -- this will wait until stdout is
*closed*.
{
output ~= line.idup;
writeln(line);
}
string[] errors;
foreach (line; p.stderr.byLine)
{
errors ~= line.idup;
writeln("Err:"~line);
}
Same thing here.
}
wait(p.pid);
None of this works though. What is strange is that when I
close out the debugger the app starts working(no console
output but I able to see that it is doing something) but is
very slow.
auto p = executeShell(`app.exe "`~f.name~`"`);
Does work, except I have no output or input. I have another
app that I do the exact same code and I can get the output and
parse it, but this is after the app terminates. I imagine the
issue here is that I'm trying to get the output while the app
is running.
Without knowing the pattern of what your app is outputting,
it's hard to tell what will happen.
The most common problem with people dealing with piped output
is not reading data off the pipe, which then makes the child
process hang trying to write to the pipe, because the buffer is
full.
For instance, if your process outputs tons of stuff to stderr,
you will hang, because you are waiting for stdout to be closed
first before you read anything from stderr, the child process
fills up stderr pipe, and is put to sleep waiting for it to be
writable, never closing stdout.
Unfortunately, std.process wraps all the pipes in File structs,
so you have almost no good mechanisms to properly read the data.
WTF?
-Steve
Seriously, I can't simply get the output in real time? Come on,
that is lame, Surely D can do better than that? How hard is it to
get a buffer? Is there any hacks? How can one communicate with an
app using std io if one can't actually communicate until the app
is closed? It makes no sense.
But note that even executeShell doesn't display the output of the
app.exe so it is more than just pipeShell.
The app just outputs text, just like almost every other text. One
shouldn't have to know any pattern, that defeats the purpose. I
should just be able to get the output of the app.exe, and also if
the app is requesting input. This isn't rocket science but it
seems someone wants to turn it in to it?
When the app.exe is running it just prints stuff out, every once
in a while it might ask for input(e.g., to overwrite the file if
it exists, but I can get around that by checking in D)... but
ultimately I just want to consolidate the output it gives so I
need access to it BEFORE the app closes. The app.exe processes
files, takes some time to do so so if I have to wait to display
anything nothing will be displayed for a long time.
