Fix Missing Keys when running apt update.

apt-keyfix.sh

#!/bin/bash

## bash <(curl -Ls https://gist.githubusercontent.com/pacmac/1395f3e8a32137c4bfdf5faeb8164f9b/raw/apt-keyfix.sh)

# Run apt update and capture the error output
error_output=$(apt update 2>&1)

# Check if the error output contains the key verification error message
if [[ $error_output =~ "The following signatures couldn't be verified because the public key is not available" ]]; then
    # Retrieve the missing keys and run the apt-key command for each one
    keys=$(grep -oE "NO_PUBKEY [0-9A-Fa-f]+" <<< "$error_output" | awk '{print $NF}')
    for key in $keys; do
        apt-key adv --keyserver keyserver.ubuntu.com --recv-keys "$key"
    done

    # Run apt update again to refresh the package lists
    apt update
fi