Разовый запуск скрипта при первой загрузке

Через systemd

# Firstboot
cat <<EOF > /etc/systemd/system/firstboot.service
[Unit]
Description=Auto-execute post install scripts
After=network.target
After=mariadb.service
Requires=mariadb.service

[Service]
ExecStart=/root/firstboot.sh
 
[Install]
WantedBy=multi-user.target
EOF

cat <<EOF > /root/firstboot.sh
#!/bin/bash

PATH=/bin:/sbin:/usr/bin:/usr/sbin:/usr/local/bin
export PATH

# Тело скрипта

systemctl disable firstboot.service
rm /root/firstboot.sh
rm /etc/systemd/system/firstboot.service
EOF

chmod +x /root/firstboot.sh

## Enable firstboot service
systemctl enable firstboot.service