And my website had some dead links due to some typo in my code. I’ve used this tool to find those dead links : linkchecker.

To simply check your website, install linkchecker and run :

linkchecker <url>

Create a service file

#/etc/systemd/system/myscript.service
[Unit]
Description=Run a script daily at 2am
After=network.target

[Service]
Type=oneshot
ExecStart=/bin/bash /myscript.sh
WorkingDirectory=/
StandardOutput=journal
StandardError=journal

[Install]
WantedBy=multi-user.target

Create a timer

#/etc/systemd/system/myscript.timer
[Unit]
Description=Run the service every day at 2am

[Timer]
OnCalendar=*-*-* 02:00:00
Persistent=true
RandomizedDelaySec=60

[Install]
WantedBy=timers.target

Reload the systemd daemon and enable the timer

sudo systemctl daemon-reload
sudo systemctl enable --now myscript.timer

Verify

sudo systemctl status myscript.timer
systemctl list-timers myscript.timer

We can run the timer right now and verify the logs:

sudo systemctl start myscript.service
sudo journalctl -u myscript.service | tail -20

Disable a timer :

sudo systemctl disable --now myscript.timer

root@Frigg:/home/mathieu]# nix-channel --list
nixos https://channels.nixos.org/nixos-25.11

Add the channel that you want to join. You can find channel list at this adress : https://status.nixos.org/

[root@Frigg:/home/mathieu]# nix-channel --add https://channels.nixos.org/nixos-26.05 nixos

[root@Frigg:/home/mathieu]# nix-channel --list
nixos https://channels.nixos.org/nixos-26.05

Update the local channel.

[root@Frigg:/home/mathieu]# nix-channel --update
unpacking 1 channels...

And update the system. There will be errors as there are differences between branches, if so correct the errors and repeat the rebuild step :

[root@Frigg:/home/mathieu]# nixos-rebuild switch

nix-channel --update

Then edit your configuration.nix and add the following line to select your kernel branch (the kernel branch has to be in the repository)

# Kernel
  boot.kernelPackages = pkgs.linuxPackages_7_0;  

I’ve selected the 7.0 branch which is the stable branch for now according to kernel.org. And in the end update your nixos and reboot :

nixos-rebuild boot
sudo reboot

networking.nftables.enable = true;

Everything went well but some of my podman containers are not working. I got the following error on some of them :

Uncaught PDOException: PDO::__construct(): php_network_getaddresses: getaddrinfo for mariadb failed: Temporary failure in name resolution

A simple check shows that the dns is not working well :

# podman exec -it wishthis getent hosts mariadb
[no response]
#

It seems that the containers that do not work are on the second network called reverse.

# podman network list
NETWORK ID    NAME         DRIVER
000000000000  podman       bridge
89192dd0cbc4  reverse      bridge

The solution i’ve found is to add the following rule to configuration.nix

networking.firewall.extraInputRules = "iifname \"podman2\" udp dport 53 accept";

Then after a “nixos-rebuild switch” the firewall rules are updated and the podman2 network is added with port 53 (DNS) allowed.

# nft list ruleset
# Warning: table ip filter is managed by iptables-nft, do not touch!
table ip filter {
        chain INPUT {
                type filter hook input priority filter; policy accept;
                counter packets 383595 bytes 45668336 jump nixos-firewall-local-only
                 counter packets 18306161 bytes 1938148280 jump NETAVARK_INPUT
        }

        chain NETAVARK_ISOLATION_2 {
        }

        chain NETAVARK_ISOLATION_3 {
                oifname "podman2" counter packets 0 bytes 0 drop
                counter packets 0 bytes 0 jump NETAVARK_ISOLATION_2
        }

        chain NETAVARK_INPUT {
                ip saddr 10.89.1.0/24 udp dport 53 counter packets 57797 bytes 4295138 accept
                ip saddr 10.89.1.0/24 tcp dport 53 counter packets 0 bytes 0 accept
        }
[...]
                iifname "podman2" udp dport 53 accept
[...]

To verify that everything works we can check on the container Bob that the dns is now working :

# podman exec -it Bob getent hosts mariadb
10.89.1.46        mariadb.dns.podman  mariadb.dns.podman mariadb

# Enable CUPS to print documents.
  services.printing.enable = true;

 # Add drivers if necessary
  services.printing.drivers = [ pkgs.brlaser ];

 # Enable Firewall rules and network protocol for printers
  services.avahi = {
  enable = true;
  nssmdns4 = true;
  openFirewall = true;
};

After using the command nixos-rebuild switch you can now configure your printer inside cups at http://localhost:631/

tput means “terminal put”, this will send commands to the terminal.

sgr0 means “Set Graphics Renditions to 0”, it will reset the terminal attributes.

There are three modes for badblocks :

• Write and read all the blocks

badblocks -w /dev/<device>

• Read-Write without erasing any data

badblocks -n /dev/<device>

• Only read data (default mode)

badblocks /dev/<device>

You can add the following options :

-v for verbose output

-o <output file> write the badblocks list to a file

-p <number> pass number

-s show the progress of the analysis

-b <size of the blocks>, it must be in octet, the default value is 1024.

In any case, it is best to make a backup before using badblocks. The tests are very time intensive, it can take hours depending on the drive speed.

I have made some tests on a 16Gb usb stick from 2008 and it has taken more than 3 hours.

• Update the channel

sudo nix-channel --update

• Apply updates

sudo nixos-rebuild switch

You can do step by step, or just do both in one command line :

nixos-rebuild switch --upgrade

You may reboot to apply major updates (ex : kernel updates).

To upgrade to a new major OS version, you need to add a channel and upgrade :

nix-channel --add https://channels.nixos.org/nixos-<version to upgrade to ex: 25.05> nixos
sudo nixos-rebuild switch --upgrade

You can also do automatic upgrades by adding the following to your configuration.nix :

{
  system.autoUpgrade.enable = true;
  # Warning "allowReboot = true" allow the upgrade to reboot the machine in order to upgrade the kernel, 
  # if set to false it will stay in the current channel and only upgrade to last version in the current channel.
  system.autoUpgrade.allowReboot = true;
}