sandbox.py

import tkinter as tk
from tkinter.scrolledtext import ScrolledText
import threading
from subprocess import Popen, PIPE


class Console(tk.Frame):

    """Simple console that can execute bash commands"""

    def __init__(self, master, *args, **kwargs):
        tk.Frame.__init__(self, master, *args, **kwargs)

        self.text_options = {"state": "disabled",
                             "bg": "black",
                             "fg": "#08c614",
                             "insertbackground": "#08c614",
                             "selectbackground": "#f01c1c"}

        self.text = ScrolledText(self, **self.text_options)

        # It seems not to work when Text is disabled...
        # self.text.bind("<<Modified>>", lambda: self.text.frame.see(tk.END))

        self.text.pack(expand=True, fill="both")

        # bash command, for example 'ping localhost' or 'pwd'
        # that will be executed when "Execute" is pressed
        self.command = ""
        self.popen = None     # will hold a reference to a Popen object
        self.running = False  # True if the process is running

        self.bottom = tk.Frame(self)

        self.prompt = tk.Label(self.bottom, text="Enter the command: ")
        self.prompt.pack(side="left", fill="x")
        self.entry = tk.Entry(self.bottom)
        self.entry.bind("<Return>", self.start_thread)
        self.entry.bind("<Command-a>", lambda e: self.entry.select_range(0, "end"))
        self.entry.bind("<Command-c>", self.clear)
        self.entry.focus()
        self.entry.pack(side="left", fill="x", expand=True)

        self.executer = tk.Button(self.bottom, text="Execute", command=self.start_thread)
        self.executer.pack(side="left", padx=5, pady=2)
        self.clearer = tk.Button(self.bottom, text="Clear", command=self.clear)
        self.clearer.pack(side="left", padx=5, pady=2)
        self.stopper = tk.Button(self.bottom, text="Stop", command=self.stop)
        self.stopper.pack(side="left", padx=5, pady=2)

        self.bottom.pack(side="bottom", fill="both")

    def clear_text(self):
        """Clears the Text widget"""
        self.text.config(state="normal")
        self.text.delete(1.0, "end-1c")
        self.text.config(state="disabled")

    def clear_entry(self):
        """Clears the Entry command widget"""
        self.entry.delete(0, "end")

    def clear(self, event=None):
        """Does not stop an eventual running process,
        but just clears the Text and Entry widgets."""
        self.clear_entry()
        self.clear_text()

    def show(self, message):
        """Inserts message into the Text wiget"""
        self.text.config(state="normal")
        self.text.insert("end", message)
        self.text.see("end")
        self.text.config(state="disabled")

    def start_thread(self, event=None):
        """Starts a new thread and calls process"""
        self.stop()
        self.running = True
        self.command = self.entry.get()
        # self.process is called by the Thread's run method
        threading.Thread(target=self.process).start()

    def process(self):
        """Runs in an infinite loop until self.running is False"""
        while self.running:
            self.execute()

    def stop(self):
        """Stops an eventual running process"""
        if self.popen:
            try:
                self.popen.kill()
            except ProcessLookupError:
                pass
        self.running = False

    def execute(self):
        """Keeps inserting line by line into self.text
        the output of the execution of self.command"""
        try:
            # self.popen is a Popen object
            self.popen = Popen(self.command.split(), stdout=PIPE, bufsize=1)
            lines_iterator = iter(self.popen.stdout.readline, b"")

            # poll() return None if the process has not terminated
            # otherwise poll() returns the process's exit code
            while self.popen.poll() is None:
                for line in lines_iterator:
                    self.show(line.decode("utf-8"))
            self.show("Process " + self.command  + " terminated.\n\n")

        except FileNotFoundError:
            self.show("Unknown command: " + self.command + "\n\n")
        except IndexError:
            self.show("No command entered\n\n")

        self.stop()


if __name__ == "__main__":
	root = tk.Tk()
	root.geometry("1050x500")
	root.title("Sandbox Environment")
	Console(root).pack(expand=True, fill="both")
	root.mainloop()