gh-256.sh

#!/bin/bash

# Check if both arguments are provided
if [ "$#" -ne 2 ]; then
    echo "Usage: $0 <owner/repo> <tag>"
    echo "Example: $0 scientificcomputing/io4dolfinx v1.1.2"
    exit 1
fi

REPO=$1
TAG=$2
URL="https://github.com/${REPO}/archive/refs/tags/${TAG}.tar.gz"

# Check for the available hashing command (Linux vs macOS)
if command -v sha256sum >/dev/null 2>&1; then
    HASH_CMD="sha256sum"
elif command -v shasum >/dev/null 2>&1; then
    HASH_CMD="shasum -a 256"
else
    echo "Error: Neither 'sha256sum' nor 'shasum' was found on your system."
    exit 1
fi

# Fetch the tarball, pipe it to the hash command, and use awk to return only the hash
curl -sL "$URL" | $HASH_CMD | awk '{print $1}'

Finds the sha256 of a release on github. Usage e.g

gh-256 finsberg/fenicsx-beat v0.2.4