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Joined 1 year ago
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Cake day: December 9th, 2023

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  • But if a hashtag has not made its way over to my instance, then it effectively does not exist to me. Even if I do see it show up and decide I want to see more content related to it, if said content has not ever made its way over to my instance then I am still left out. The great thing about being able about able to check out what is on other instances is that I am no longer restricted to whatever the people on my instance are interested in.

    This a completely different experience from Lemmy, where I was immediately able to go to a bunch of different instances, look through their communities, and go: “I want to subscribe to this one, this one, and this one!”



  • People are not generally as self-reflective as you might think; when someone settles upon a core belief, they tend to stick with it for the rest of their lives, with any challenge to it being treated as a threat rather than as a potential opportunity for growth. You might think that when a core belief is completely wrong and leads to disastrous negative consequences that this might at be enough to lead someone to give it up, but strangely the mind does not actually work this way.

    (I mean, I am not saying that these people are not also evil and/or oily snakes, but I think that there is value in observing the mental fallacies at work in others so that we can better spot them at work in ourselves, since our own mind is the one thing that we have at least some limited control over.)



  • I created a script that I dropped into /etc/cron.hourly which does the following:

    1. Use rsync to mirror my root partition to a btrfs partition on another hard drive (which only updates modified files).
    2. Use btrfs subvolume snapshot to create a snapshot of that mirror (which only uses additional storage for modified files).
    3. Moves “old” snapshots into a trash directory so I can delete them later if I want to save space.

    It is as follows:

    #!/usr/bin/env python
    from datetime import datetime, timedelta
    import os
    import pathlib
    import shutil
    import subprocess
    import sys
    
    import portalocker
    
    DATETIME_FORMAT = '%Y-%m-%d-%H%M'
    BACKUP_DIRECTORY = pathlib.Path('/backups/internal')
    MIRROR_DIRECTORY = BACKUP_DIRECTORY / 'mirror'
    SNAPSHOT_DIRECTORY = BACKUP_DIRECTORY / 'snapshots'
    TRASH_DIRECTORY = BACKUP_DIRECTORY / 'trash'
    
    EXCLUDED = [
        '/backups',
        '/dev',
        '/media',
        '/lost+found',
        '/mnt',
        '/nix',
        '/proc',
        '/run',
        '/sys',
        '/tmp',
        '/var',
    
        '/home/*/.cache',
        '/home/*/.local/share/flatpak',
        '/home/*/.local/share/Trash',
        '/home/*/.steam',
        '/home/*/Downloads',
        '/home/*/Trash',
    ]
    
    OPTIONS = [
        '-avAXH',
        '--delete',
        '--delete-excluded',
        '--numeric-ids',
        '--relative',
        '--progress',
    ]
    
    def execute(command, *options):
        print('>', command, *options)
        subprocess.run((command,) + options).check_returncode()
    
    execute(
        '/usr/bin/mount',
        '-o', 'rw,remount',
        BACKUP_DIRECTORY,
    )
    
    try:
        with portalocker.Lock(os.path.join(BACKUP_DIRECTORY,'lock')):
            execute(
                '/usr/bin/rsync',
                '/',
                MIRROR_DIRECTORY,
                *(
                    OPTIONS
                    +
                    [f'--exclude={excluded_path}' for excluded_path in EXCLUDED]
                )
            )
    
            execute(
                '/usr/bin/btrfs',
                'subvolume',
                'snapshot',
                '-r',
                MIRROR_DIRECTORY,
                SNAPSHOT_DIRECTORY / datetime.now().strftime(DATETIME_FORMAT),
            )
    
            snapshot_datetimes = sorted(
                (
                    datetime.strptime(filename, DATETIME_FORMAT)
                    for filename in os.listdir(SNAPSHOT_DIRECTORY)
                ),
            )
    
            # Keep the last 24 hours of snapshot_datetimes
            one_day_ago = datetime.now() - timedelta(days=1)
            while snapshot_datetimes and snapshot_datetimes[-1] >= one_day_ago:
                snapshot_datetimes.pop()
    
            # Helper function for selecting all of the snapshot_datetimes for a given day/month
            def prune_all_with(get_metric):
                this = get_metric(snapshot_datetimes[-1])
                snapshot_datetimes.pop()
                while snapshot_datetimes and get_metric(snapshot_datetimes[-1]) == this:
                    snapshot = SNAPSHOT_DIRECTORY / snapshot_datetimes[-1].strftime(DATETIME_FORMAT)
                    snapshot_datetimes.pop()
                    execute('/usr/bin/btrfs', 'property', 'set', '-ts', snapshot, 'ro', 'false')
                    shutil.move(snapshot, TRASH_DIRECTORY)
    
            # Keep daily snapshot_datetimes for the last month
            last_daily_to_keep = datetime.now().date() - timedelta(days=30)
            while snapshot_datetimes and snapshot_datetimes[-1].date() >= last_daily_to_keep:
                prune_all_with(lambda x: x.date())
    
            # Keep weekly snapshot_datetimes for the last three month
            last_weekly_to_keep = datetime.now().date() - timedelta(days=90)
            while snapshot_datetimes and snapshot_datetimes[-1].date() >= last_weekly_to_keep:
                prune_all_with(lambda x: x.date().isocalendar().week)
    
            # Keep monthly snapshot_datetimes forever
            while snapshot_datetimes:
                prune_all_with(lambda x: x.date().month)
    except portalocker.AlreadyLocked:
        sys.exit('Backup already in progress.')
    finally:
        execute(
            '/usr/bin/mount',
            '-o', 'ro,remount',
            BACKUP_DIRECTORY,
        )