mine

#!/bin/bash

# create new blocks (commits)
# The ledger and verified transactions are committed then
# the script works to find a number that causes the commit to start
# with a number of zeros.
#
# The hash of the commit proves the miner worked to find the commit
# (or got really lucky). The proof of work lets us trust this commit.
# It took the miner time, energy, and money to create it.
# More details on Proof of work in the readme.
set -uo pipefail

source ${BASH_SOURCE%/*}/.helpers.sh

# Commit the state of the chain.
git add ledger verified

# This is the number we'll fiddle with to cause the hash to start with zeros.
# N.B. Gitcash doesn't require a nonce because a commit's hash is created from
# data that includes the current time. Relying  on time would limit githash
# mining to 1 hash per second, the resolution of git's author and commit date.
nonce=0

# A valid commit must start with this string to be valid. A longer prefix
# will require more tries to find, but 0 isn't special.
#
# Production blockchains adjust difficulty based on the rate blocks are found.
# If blocks are found often the difficulty is increased to make blocks more
# expensive.
target='^000'

# Create the new commit.
git commit -m "$nonce" --allow-empty -q

# Amend the commit with a new message as long as the target is not met.
while [[ ! $(git rev-parse HEAD) =~ $target ]]; do
  let nonce++
  git commit --amend -m "$nonce" --allow-empty -q
done

echo -n "Block created "
git rev-parse HEAD

git log --oneline --decorate --all --graph -n 6