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    "# Running a Python script as a Systemd service\n",
    "This is very simple, first we need to create a systmed \"unit\", in `/etc/systemd/system/foo.service`\n",
    "```bash\n",
    "[Unit]\n",
    "Description=Abracadabra\n",
    "After=network.target\n",
    "\n",
    "[Service]\n",
    "Type=simple\n",
    "User=bob\n",
    "Restart=on-failure\n",
    "RestartSec=3\n",
    "ExecStart=/usr/bin/python3 /home/bob/test_daemon.py\n",
    "[Install]\n",
    "WantedBy=multi-user.target\n",
    "```\n",
    "\n",
    "Then, we can enable and start the service with\n",
    "```bash\n",
    "systemctl enable foo.service\n",
    "systemctl start foo\n",
    "```\n",
    "\n",
    "## What happens to the stdout and stderr?\n",
    "They can be checked by calling `journalctl -u foo`. Assuming `test_daemon.py` was:\n",
    "```python\n",
    "from datetime import datetime\n",
    "from time import sleep\n",
    "import sys\n",
    "\n",
    "print(\"Started abracadabra\")\n",
    "\n",
    "while True:\n",
    "    curtime = datetime.now().strftime('%X')\n",
    "    print(\"Hi! Current time is: \", curtime)\n",
    "    sleep(2)\n",
    "```\n",
    "we should see\n",
    "```bash\n",
    "$ sudo journalctl -u foo\n",
    "Okt 09 21:07:18 etna python3[13499]: Started abracadabra\n",
    "Okt 09 21:07:18 etna python3[13499]: Hi! Current time is:  21:07:18\n",
    "Okt 09 21:07:20 etna python3[13499]: Hi! Current time is:  21:07:20\n",
    "Okt 09 21:07:22 etna python3[13499]: Hi! Current time is:  21:07:22\n",
    "Okt 09 21:07:24 etna python3[13499]: Hi! Current time is:  21:07:24\n",
    "Okt 09 21:07:26 etna python3[13499]: Hi! Current time is:  21:07:26\n",
    "Okt 09 21:07:28 etna python3[13499]: Hi! Current time is:  21:07:28\n",
    "Okt 09 21:07:30 etna python3[13499]: Hi! Current time is:  21:07:30\n",
    "```\n",
    "\n",
    "## Redirecting stdout/stderr to a file\n",
    "We can ask Systemd to do this by adding these lines in `/etc/systemd/system/foo.service`\n",
    "```bash\n",
    "[Service]\n",
    "---snip---\n",
    "ExecStart=/usr/bin/python3 /home/bob/test_daemon.py\n",
    "StandardOutput=file:/var/log/foo/stdout\n",
    "StandardError=file:/var/log/foo/stderr\n",
    "---snip---\n",
    "```\n",
    "## But nothing gets written to `/var/log/foo/stdout`!\n",
    "This is because python [buffers stdout](https://unix.stackexchange.com/questions/182537/write-python-stdout-to-file-immediately) if it is not a console. If we really want to see the stdout of our daemon as soon as they are printed, we need to disable this buffering. This can be achieved by starting python with `-u` flag. So, the systemd unit file changes to:\n",
    "\n",
    "```bash\n",
    "[Unit]\n",
    "Description=Abracadabra\n",
    "After=network.target\n",
    "\n",
    "[Service]\n",
    "Type=simple\n",
    "User=bob\n",
    "Restart=on-failure\n",
    "RestartSec=3\n",
    "ExecStart=/usr/bin/python3 /home/bob/test_daemon.py\n",
    "StandardOutput=file:/var/log/foo/stdout\n",
    "StandardError=file:/var/log/foo/stderr\n",
    "[Install]\n",
    "WantedBy=multi-user.target\n",
    "```\n",
    "\n",
    "That's it! Now `/var/log/foo/stdout` should be populated with whatever `test_daemon.py` prints. \n"
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