Jekyll hooks to copy the _site folder somewhere else and commit and push to a remote repo, e.g. GitHub.io

copy_site.rb

Jekyll::Hooks.register :site, :post_write do |site|
    Jekyll.logger.info "site.dest: ", site.dest
    Jekyll.logger.info "site.source: ", site.source
    ioDest = '/Users/james/Projects/jamesstout.github.io'
    Jekyll.logger.info "GitHub.io dest: ", ioDest
    
    hash = `git rev-parse --short HEAD`

    Jekyll.logger.info "hash: ", hash

    lastHashFile = ioDest + '/lastHash'

    if ::File.exist?(lastHashFile)
        lastHash = File.read(lastHashFile)
        Jekyll.logger.info "lastHash: ", lastHash
        if lastHash == hash
            Jekyll.logger.info "Hashes equal: ",  "not copying, committing or pushing"
        else
            Jekyll.logger.info "Hashes NOT equal: ", "copying, git commit and pushing"
            Jekyll.logger.info "Copying _site to: ", ioDest
            FileUtils.cp_r(site.dest + '/.', ioDest, :remove_destination => true)
            FileUtils.cd(ioDest)
            Jekyll.logger.info "pwd: ", `pwd`
            Jekyll.logger.info "git:", "Committing new build"
            `git add .`
            `git commit -a -m "build"`
            Jekyll.logger.info "git: ", "Pushing new build"
            `git push`
            Jekyll.logger.info "Updating hash: ", hash
            File.write(lastHashFile, hash)
        end
    else
        Jekyll.logger.error "lastHash file doesn't exist: ", lastHashFile
        Jekyll.logger.error "Solution: ", "Try the build again."
        File.write(lastHashFile, 'xxxxxx')
    end
end