Linux Commands & Snippets
Interface Priority on Linux
sudo nmcli connection modify 'enter ssid here' ipv4.route-metric 50 sudo nmcli connection up 'enter ssid here' Install sudo on Debian 12
su apt install sudo Add a user to sudo group:
su -l adduser <your_username_here> sudo logout Change IP Addressing from DHCP to Static
sudo nano /etc/network/interfaces auto <interface> iface <interface> inet static address x.x.x.x netmask 255.255.255.0 gateway xx.xx.xx dns-nameservers xx.xx.xx sudo systemctl restart networking.service sudo systemctl status networking.service Change hostname (Debian 9/10/11/12)
hostnamectl set-hostname {name-here} sudo hostnamectl set-hostname enkielhostsample sudo nano /etc/hosts # replace old hostname references Check DNS (systemd-resolved)
resolvectl status resolvectl dns <interface> <dns address>,<dns address> Remove folder contents
sudo rm -rf foldername/* Missing disk space on new installation
lvextend -l +100%FREE /dev/ubuntu-vg/ubuntu-lv resize2fs /dev/ubuntu-vg/ubuntu-lv Root file system requires manual fsck
fsck -yf /dev/sda1 “Reading package lists… Error!”
sudo apt clean sudo rm -rf /var/lib/apt/lists/* sudo apt update Setup mobile Linux/Termux storage sharing
termux-setup-storage Kill zombied application
ps -eo pid,ppid,state,cmd | awk '$3=="Z" { print "Zombie PID:", $1, "Parent PID:", $2 }' kill -HUP <parentPID> Allow password auth only for a single IP (sshd_config)
# Default: key-based only for everyone PasswordAuthentication no PubkeyAuthentication yes # Exception: allow password login from specific IP Match Address 203.0.113.25 PasswordAuthentication yes Steps: 1) Edit sshd_config and add the block above.
2) Test syntax: sudo sshd -t
3) Reload SSH: sudo systemctl reload sshd
Fix DNS configuration
sudo nano /etc/resolv.conf # Example nameserver 8.8.8.8 nameserver 1.1.1.1 # If systemd-resolved keeps overwriting: sudo systemctl disable systemd-resolved sudo systemctl stop systemd-resolved sudo rm /etc/resolv.conf echo -e "nameserver 8.8.8.8\nnameserver 1.1.1.1" | sudo tee /etc/resolv.conf Codex clear session caches
cd ~/.codex/sessions rm -rf *
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