text: const cp = require('child_process');
  const p = require('path');
  const semver = require('semver');
  
  function execSync(cmd) {
    cp.execSync(cmd, { stdio: ['inherit', 'inherit', 'inherit'] });
  }
  
  function execSyncRead(cmd) {
    return String(cp.execSync(cmd, { stdio: ['inherit', 'pipe', 'inherit'] })).trim();
  }
  
  function execSyncSilently(cmd) {
    cp.execSync(cmd, { stdio: ['ignore', 'ignore', 'ignore'] });
  }
  
  function validateEnv() {
    if (!process.env.CI || !process.env.TRAVIS) {
      throw new Error(`releasing is only available from Travis CI`);
    }
  
    if (process.env.TRAVIS_BRANCH !== 'master') {
      console.error(`not publishing on branch ${process.env.TRAVIS_BRANCH}`);
      return false;
    }
  
    if (process.env.TRAVIS_PULL_REQUEST !== 'false') {
      console.error(`not publishing as triggered by pull request ${process.env.TRAVIS_PULL_REQUEST}`);
      return false;
    }
  
    return true;
  }
  
  function calcNewVersion() {
    const latestVersion = execSyncRead(`npm view ${process.env.npm_package_name}@latest version`);
    console.log(`latest version is: ${latestVersion}`);
    console.log(`package version is: ${process.env.npm_package_version}`);
    if (semver.gt(process.env.npm_package_version, latestVersion)) {
      return semver.inc(process.env.npm_package_version, 'patch');
    } else {
      return semver.inc(latestVersion, 'patch');
    }
  }
  
  function copyNpmRc() {
    execSync(`rm -f package-lock.json`);
    const npmrcPath = p.resolve(`${__dirname}/.npmrc`);
    execSync(`cp -rf ${npmrcPath} .`);
  }
  
  function tagAndPublish(newVersion) {
    console.log(`new version is: ${newVersion}`);
    execSync(`npm version ${newVersion} -m "v${newVersion} [ci skip]"`);
    execSync(`npm publish --tag latest`);
    execSyncSilently(`git push deploy --tags`);
  }
  
  function run() {
    if (!validateEnv()) {
      return;
    }
    copyNpmRc();
    tagAndPublish(calcNewVersion());
  }
  
  run();
  