get console output in a qt widget, tested in Blender.

realtime-output.py

import sys
import subprocess
from PySide2.QtWidgets import QLineEdit, QApplication, QMainWindow, QTextEdit, QVBoxLayout, QPushButton, QWidget
from PySide2.QtCore import QTimer
from PySide2.QtGui import QColor, QTextCursor


class RealTimeOutputApp(QMainWindow):
    def __init__(self):
        super().__init__()

        self.setWindowTitle("Real-Time Output Example")
        self.central_widget = QWidget()
        self.setCentralWidget(self.central_widget)

        layout = QVBoxLayout(self.central_widget)

        self.command_line = QLineEdit()
        layout.addWidget(self.command_line)
        
        self.text_edit = QTextEdit()
        layout.addWidget(self.text_edit)

        self.start_button = QPushButton("List Files in Directory")
        layout.addWidget(self.start_button)

        self.start_button.clicked.connect(self.start_command)
        self.process = None
        self.timer = QTimer(self)
        self.timer.timeout.connect(self.read_output)
        self.read_timer_started = False

    def start_command(self):
        try:
            self.text_edit.clear()
            command = self.command_line.text()  # Get the command from the QLineEdit
            
            #command = ["cmd", "/c", "tree"]  # Sample command to list files in a directory
            self.process = subprocess.Popen(command, 
            stdout=subprocess.PIPE, stderr=subprocess.PIPE, 
            universal_newlines=True, errors='ignore')

            # Start a timer to periodically check for new output
            if not self.read_timer_started:
                self.timer.start(1)  # Adjust the interval as needed (every x milisec)
                self.read_timer_started = True
        except Exception as e:
            self.add_error(str(e))

    def read_output(self):
        if not self.process:
            self.add_error("No process avaiable")
            return
        
        stdout_line = self.process.stdout.read()  # Adjust the buffer size as needed
        stderr_line = self.process.stderr.read()
        
        if stdout_line:
            self.text_edit.moveCursor(QTextCursor.End)
            self.text_edit.insertPlainText(stdout_line)
            #self.repaint()
        
        if stderr_line:
            # Print error output in red
            self.add_error(stderr_line)
        
        if not stdout_line and not  stderr_line and self.process.poll() != None:
            # The process has finished
            self.process = None
            self.read_timer_started = False
            self.timer.stop()
                
                   
    def add_error(self, lines):
        color = "red"
        if lines.lower().startswith("warning"):
            color = "yellow"
            
        self.text_edit.setTextColor(QColor(color))
        self.text_edit.insertPlainText(lines)
        self.text_edit.setTextColor(QColor("black"))
        
        

main_window = RealTimeOutputApp()
main_window.show()