Run logrotate as specific user

As promised, a "close enough" to ring buffer program, in a few lines of Perl.

To use it, pass it the size of the log files you want, in bytes (give or take one line), and two or more log files. It'll switch between the log files every X bytes. I'm sure there is already a program out there to do this, but I couldn't find it with a quick search. E.g.,

$ your-app | log-splitter 1048576 /var/log/your-app/log1 /var/log/your-app/log2

assuming, of course, that the file log-splitter is executable, in $PATH, and contains:

#!/usr/bin/perl
use warnings qw(all);
use strict;
use autodie;
use Carp;
use Fcntl qw(SEEK_SET);
use IO::Handle;

# yes, we truncate all logs at start. Sorry.
@ARGV >= 2 or croak "Usage: $0 log-size log-file...";
my ($max_size, @lognames) = @ARGV;
my @logs = map {
    open my $fh, '+>', $_;
    $fh->autoflush(1);
    $fh;
} @lognames;

my $current_size = $max_size;
my $current_log  = $#logs;
while (defined(my $line = <STDIN>)) {
    if ($current_size >= $max_size) {
        $current_log  = ($current_log + 1) % @logs;
        $current_size = 0;
        seek($logs[$current_log], 0, SEEK_SET);
        truncate($logs[$current_log], 0);
    }

    $current_size += length($line);
    print {$logs[$current_log]} $line;
}

close($_) foreach @logs;

To clarify any licensing questions on that code:

To the extent possible under law, Anthony DeRobertis has waived all copyright and related or neighboring rights to the above program (log-splitter). This work is published from: United States.

logrotate can be run as an ordinary user, without administrative privileges, to rotate logs for that user.

# Create a local per-user configuration file
cat >.logrotate.conf <<'X'
/home/mike/tmp/qqq.log {
    notifempty
    missingok
    size 1M
    rotate 3
}
X

# Run logrotate with that configuration file
/usr/sbin/logrotate -v -s .logrotate.state .logrotate.conf

I've removed your daily criterion because you wanted purely a size-based check, and this would have limited any possible action to just once a day (the first time each day that logrotate is run, as it happens). I've replaced create with missingok so that it's up to your actual rclone job to create the output file rather than logrotate.

Then put the logrotate command into your user's crontab file:

# Capture any existing crontab entries
crontab -l >.crontab

# Append ours to the list
echo '0 * * * * /usr/sbin/logrotate -s .logrotate.state .logrotate.conf >>.crontab.log 2>&1' >>.crontab

# Reload crontab
crontab .crontab

Using this example, output from the command will be written to .crontab.log, and you'll probably want a logrotate entry to cycle or reset it monthly.