How to avoid overriding destination file if rename target already exists

[fedulovivan]

Hello, is it possible to perform additional check before writing destination file, and omit renaming operation if destination file already exists?

My usecase is creating real config files from samples:

gulp
  .src("config/*.sample")
  .pipe(rename({extname:""}))
  .pipe(gulp.dest("config/"));

[heikki]

https://github.com/hparra/gulp-rename#usage -> rename via function

[yocontra]

@fedulovivan gulp.dest has an overwrite option which you can set to false

[fedulovivan]

@contra Probably this is some kind undocumented dest option.

$ gulp -v
[10:09:06] CLI version 3.9.0
[10:09:06] Local version 3.9.0

In fact these two options below does not work:

.pipe(gulp.dest("config/", {overwrite: false}))
.pipe(gulp.dest("config/", {override: false}))

[heikki]

@fedulovivan It is in 4.0 branch -> https://github.com/gulpjs/gulp/blob/4.0/docs/API.md#optionsoverwrite

[fedulovivan]

@heikki Right, thanks! This new option actually listed in 4.0.0 change log. update: is it turned out gulp v4 is currently alpha

[dac514]

I would also like this feature but Gulp 4 is still in alpha?

Can someone post an example of how to do this without using the new feature? I looked at rename and it's not what I'm after.

Code:

gulp.task("steps", function stepsTask(cb) {
    var GulpYaddaSteps = require('gulp-yadda-steps');
    gulp.src(__dirname + '/tests/features/**/*.feature')
        .pipe(new GulpYaddaSteps())
        .pipe(gulp.dest(__dirname + '/tests/steps/, {overwrite: false}'));
});

Expected: Existing files are not overwritten Actual: Existing files are overwritten

[dewwwald]

If you would like to see two solutions check this out.

http://stackoverflow.com/questions/38827441/gulp-write-file-if-none-exist/38828128#38828128