Need to parse command-line arguments in a bash script? Personally I always use this method: #!/bin/bash   while [[ "$#" -gt 0 ]]; do case $1 in -d|–deploy) deploy="$2"; shift ;; -u|–uglify) uglify=1 ;; *) echo "Unknown parameter passed: $1"; exit 1 ;; esac shift done   echo "Should deploy? $deploy" echo "Should uglify? $uglify"#!/bin/bash […]

There is Debian package named “iptables-persistent”. iptables-persistent makes sure iptables rules survive a reboot. To install it just type this command: apt-get -y install iptables-persistentapt-get -y install iptables-persistent To install it in an automated way check this: Bash Install Iptables-Persistent Automatically Other useful info can be found here: https://wiki.debian.org/iptables

Check if iptables-persistent is installed, else install it: if [[ $(dpkg -s iptables-persistent) != *"Status: install ok installed"* ]]; then echo iptables-persistent iptables-persistent/autosave_v4 boolean true | sudo debconf-set-selections echo iptables-persistent iptables-persistent/autosave_v6 boolean true | sudo debconf-set-selections apt-get -y install iptables-persistent fiif [[ $(dpkg -s iptables-persistent) != *"Status: install ok installed"* ]]; then echo iptables-persistent iptables-persistent/autosave_v4 […]

You can use awk to trim a string, example: echo " test " | awk ‘{$1=$1};1’echo " test " | awk ‘{$1=$1};1’ Another way is to use sed like this: echo " test " | sed -e ‘s/^[[:space:]]*//’ -e ‘s/[[:space:]]*$//’echo " test " | sed -e ‘s/^[[:space:]]*//’ -e ‘s/[[:space:]]*$//’ And also xargs can be used: […]

Here is a bash command to get name of ethernet network interface: ip link | awk -F: ‘$0 !~ "lo|tun|vir|wg|wl|^[^0-9]"{print $2;getline}’ | awk ‘{$1=$1};1’ip link | awk -F: ‘$0 !~ "lo|tun|vir|wg|wl|^[^0-9]"{print $2;getline}’ | awk ‘{$1=$1};1’ It will exclude lo (local), tun0 (openvpn), wg0 (wireguard), wl* (wireless), etc. If you have multiple ethernet network interface and […]