git pre-receive 钩子求助

老铁们，请教怎么在脚本里执行 git 命令
想拦截掉某些 push 包含特定的 commit
百度谷歌半天，都不行


服务器上现有脚本如下：
#!/usr/bin/env ruby


# This file was placed here by GitLab. It makes sure that your pushed commits
# will be processed properly.


refs = $stdin.read
gl_id = ENV.delete('GL_ID')
protocol = ENV.delete('GL_PROTOCOL')
repo_path = Dir.pwd
gl_repository = ENV['GL_REPOSTTORY']


def increase_reference_counter(gl_repository, repo_path)
result = GitlabNet.new.pre_receive(gl_repository)

result && result['reference_counter_increased']
end

require_relative '../lib/gitlab_custom_hook'
require_relative '../lib/gitlab_access'
require_relative '../lib/gitlab_net'


# It’s important that on pre-receive 'increase_reference_counter' gets executed
# last so that it only runs if everything else succeeded. On post-receive on the
# other hand, we run GitlabPostReceive first because the push is already done
# and we don’t want to skip it if the custom hook fails.
if GitlabAccess.new(gl_repository, repo_path, gl_id, refs, protocol).exec &&
GitlabCustomHook.new(repo_path, gl_id).pre_receive(refs) &&
increase_reference_counter(gl_repository, repo_path)
exit 0
else
exit 1
end