How to pass data to console app and handle it's output?

Question

I have got console app that get parameters to start and then output result of calculation.

Example (from docs):

gdaltransform -s_srs EPSG:28992 -t_srs EPSG:31370

177502 311865

In step-by step mode it's work like:

gdaltransform -s_srs EPSG:28992 -t_srs EPSG:31370 [press enter]
I input from keyboard: 177502 311865 [press enter]
it's print on screen new coordinates: 244296.723070577 165937.350438393 1.60975147597492

I need to call it's from D, pass input parametrs, and handle it's output.

It's seems that I need use pipeShell for it, but I can't understand how to use it.

Here is my code:

import std.stdio;
import std.process;
import std.file;

void main()
{
    auto pipes = pipeProcess(["gdaltransform", " -s_srs epsg:4326 -t_srs EPSG:3857"], Redirect.stdout);
    scope(exit) wait(pipes.pid);
}

But how to read of gdaltransform output to variable and then terminate app?

Jack Applegame · Accepted Answer · 2016-08-23 09:36:40Z

2

import std.stdio;
import std.process;

void main() {
    // spawn child process by pipeProcess
    auto pipes = pipeProcess(["gdaltransform", "-s_srs", "EPSG:28992", "-t_srs", "EPSG:31370"], Redirect.all);

    // or by pipeShell
    //auto pipes = pipeShell("gdaltransform -s_srs EPSG:28992 -t_srs EPSG:31370", Redirect.all);

    scope(exit) {
        // send terminate signal to the child process
        kill(pipes.pid);
        // waiting for terminate
        wait(pipes.pid);
    }

    // write data to child's stdin
    pipes.stdin.writeln("177502, 311865");

    // close child's stdin
    pipes.stdin.close();

    // read data from child's stdout
    string line = pipes.stdout.readln();

    write("result: ", line);
}

edited Aug 23, 2016 at 9:36

answered Aug 23, 2016 at 9:30

Jack Applegame

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2 Comments

sigod Over a year ago

Is there a specific reason why you call close? Maybe flush will be sufficient?

Jack Applegame Over a year ago

flush should be sufficient, but on my CentOS 7 it shouldn't. I don't know why. Maybe gdaltransform doesn't flush its stdio

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