For dApp development, its common for scripts to use `PRIVATE_KEY` and `PUBLIC_KEY` so for security reasons I automatically generate a temporary (but valid) keypair. I load this in with my `.bashrc`. Type in `keygen` to automatically generate a new keypair and assign to their respective variable names.

ethereum-keygen.sh

#!/bin/bash env

keygen() {

    PREFIX="$HOME/.evm/"
    KEY="$(echo "$PREFIX")key"
    PUB="$(echo "$PREFIX")pub"
    PRIV="$(echo "$PREFIX")priv"
    ADDRESS="$(echo "$PREFIX")address"

    # Generate the private and public keys
    openssl ecparam -name secp256k1 -genkey -noout | openssl ec -text -noout >"$KEY" 2>/dev/null
    # Extract the public key and remove the EC prefix 0x04
    cat "$KEY" | grep pub -A 5 | tail -n +2 | tr -d '\n[:space:]:' | sed 's/^04//' >"$PUB"

    # Extract the private key and remove the leading zero byte
    cat "$KEY" | grep priv -A 3 | tail -n +2 | tr -d '\n[:space:]:' | sed 's/^00//' >"$PRIV"

    # Generate the hash and take the address part
    cat "$PUB" | keccak-256sum -x -l | tr -d ' -' | tail -c 41 >"$ADDRESS"

    export EVM_PRIVATE_KEY=$(cat "$PRIV")
    export EVM_ADDRESS="0x$(cat "$ADDRESS")"

    echo "EVM_ADDRESS = $EVM_ADDRESS"
    echo "EVM_PRIVATE_KEY = $EVM_PRIVATE_KEY"
}

export -f keygen