I'm running Debian/Trixie on an AMD64 system. I have an old wifi adapter that Linux has problems with that works once I run:

/usr/sbin/modprobe brcmfmac
echo 13b1 0bdc > /sys/bus/usb/drivers/brcmfmac/new_id

However when I add those lines to the root's crontab using # crontab -e as

@reboot /usr/sbin/modprobe brcmfmac
@reboot echo 13b1 0bdc > /sys/bus/usb/drivers/brcmfmac/new_id

the second line fails. I get an e-mail stating "/bin/sh: 1: cannot create /sys/bus/usb/drivers/brcmfmac/new_id: Directory nonexistent"

I'm not sure if the modprobe is working or if the module is being loaded without it. It's likely that debian detects the need for the module and loads it.

Anyway, that got me down the rabbit hole to try to find where the crontab file is.

 ls -l /root/cron*
ls: cannot access '/root/cron*': No such file or directory


# whereis crontab
crontab: /usr/bin/crontab /etc/crontab /usr/share/man/man1/crontab.1.gz /usr/share/man/man5/crontab.5.gz

so it's not in the location that you'd expect. Nor can I find it in /etc/. The various cron files there don't contain the lines I;m looking for.

However, running crontab -e as root definitely shows the file I expect to see.  Specifically:

# Edit this file to introduce tasks to be run by cron.
# Each task to run has to be defined through a single line
# indicating with different fields when the task will be run
# and what command to run for the task
# To define the time you can provide concrete values for
# minute (m), hour (h), day of month (dom), month (mon),
# and day of week (dow) or use '*' in these fields (for 'any').
# Notice that tasks will be started based on the cron's system
# daemon's notion of time and timezones.
# Output of the crontab jobs (including errors) is sent through
# email to the user the crontab file belongs to (unless redirected).
# For example, you can run a backup of all your user accounts
# at 5 a.m every week with:
# 0 5 * * 1 tar -zcf /var/backups/home.tgz /home/
# For more information see the manual pages of crontab(5) and cron(8)
# m h  dom mon dow   command
@reboot /usr/sbin/modprobe brcmfmac
@reboot echo 13b1 0bdc > /sys/bus/usb/drivers/brcmfmac/new_id

Looking at systemd-timers doesn't show anything obvious either.

Can anyone explain how Trixie is handling crontabs now?

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