How can I use Textual to tail a file and display the output in a Log widget?

[kyrlon]

Are there specific methods or examples that demonstration this functionality? I have come across the textual app Toolong mentioned from what I believe is the creator's blog. It seems great, and I’m wondering if it’s possible to integrate it as a 'widget' in my current projects

[willmcgugan]

It sure is. Feel free to pull anything you want from Toolong.

[kyrlon]

I ended up doing something like this without adding threads to the code, which I was attempting to avoid. The only caveat I see with this example is if I set the interval faster than a second, the logging displayed gets kind of weird/butchered

from textual.app import App, ComposeResult
from textual.widgets import Log
import os, platform
import subprocess
import time

class LogApp(App):

    def __init__(self, file_name, **kwargs):
        super().__init__(**kwargs)
        self.current = None
        self.curino = None
        self.file_name = file_name

    def compose(self) -> ComposeResult:
        yield Log()

    def on_ready(self) -> None:
        self.logg = self.query_one(Log)
        self.logg.write_line("Hello, World!")

    
    async def on_mount(self) -> None:
        self.timer_task = self.set_interval(1, self.tail)

    
    def tail(self):
        #inspiried by https://stackoverflow.com/a/39213830/13642249
        if not (self.current and self.curino):
            self.current = open(self.file_name, "r", encoding="utf-8")
            self.curino = os.fstat(self.current.fileno()).st_ino
        while True:
            line = self.current.readline().strip()
            if not line:
                try:
                    if os.stat(self.file_name).st_ino != self.curino:
                        new = open(self.file_name, "r", encoding="utf-8")
                        self.current.close()
                        self.current = new
                        self.curino = os.fstat(self.current.fileno()).st_ino
                except IOError:
                    pass
            else:
                self.logg.write_line(line)
                return

if __name__ == "__main__":
    target_host = "8.8.8.8"
    file_name = f"test_{int(time.time())}.log"
    ff = open(file_name, "w")
    if platform.system().lower() == "windows".lower():
        cmd = f"ping {target_host} /t".split()
    else:
        cmd = f"ping {target_host}".split()
    process = subprocess.Popen(cmd, stdout=ff)

    app = LogApp(file_name=file_name)
    app.run()

Quick Demo: