How do you create a file from a string in Gulp?

This can also be done with vinyl-source-stream. See this document in the gulp repository.

var gulp = require('gulp'),
    source = require('vinyl-source-stream');

gulp.task('some-task', function() {
    var stream = source('file.txt');

    stream.end('some data');
    stream.pipe(gulp.dest('output'));
});

It's pretty much a one-liner in node:

require('fs').writeFileSync('dist/version.txt', '1.2.3');

Or from package.json:

var pkg = require('./package.json');
var fs = require('fs');
fs.writeFileSync('dist/version.txt', 'Version: ' + pkg.version);

---

I'm using it to specify a build date in an easily-accessible file, so I use this code before the usual return gulp.src(...) in the build task:

require('fs').writeFileSync('dist/build-date.txt', new Date());

According to the maintainer of Gulp, the preferred way to write a string to a file is using fs.writeFile with the task callback.

var fs = require('fs');
var gulp = require('gulp');

gulp.task('taskname', function(cb){
  fs.writeFile('filename.txt', 'contents', cb);
});

Source: https://github.com/gulpjs/gulp/issues/332#issuecomment-36970935

If you'd like to do this in a gulp-like way, you can create a stream of "fake" vinyl files and call pipe per usual. Here's a function for creating the stream. "stream" is a core module, so you don't need to install anything:

const Vinyl = require('vinyl')

function string_src(filename, string) {
  var src = require('stream').Readable({ objectMode: true })
  src._read = function () {
    this.push(new Vinyl({
      cwd: "",
      base: "",
      path: filename,
      contents: Buffer.from(string, 'utf-8')
    }))
    this.push(null)
  }
  return src
}

You can use it like this:

gulp.task('version', function () {
  var pkg = require('package.json')
  return string_src("version", pkg.version)
    .pipe(gulp.dest('build/'))
})