Gulp4 watch不监听文件变更问题求助

Let's break down what's going on here and fix your issue. First, I've run into similar headaches with Gulp 4 on Linux systems, so this is likely a combination of Gulp 4's watch behavior and Linux file system quirks—not a bug, just an easy-to-miss gotcha.

First, Rule Out Simple Fixes #

1. Check Gulp Version Consistency: Make sure you're running the local Gulp 4 package, not a global Gulp 3 installation. Run npx gulp --version in your project directory—this guarantees you're using the Gulp 4 version you installed locally, not an outdated global copy that might conflict.

2. Fix the Watch Task's Async Handling: In your second Gulp 4 example, you have this:

   function watch( done ) {
     gulp.watch( 'src/style.scss', gulp.series( sass ) );
     done();
   }
   

   Calling done() tells Gulp the watch task is finished, but gulp.watch runs indefinitely to listen for changes. Remove the done() call here—this keeps the watch task active without signaling premature completion.

The Real Issue: Linux File System Watch Limitations #

On CentOS 7, Gulp 4 uses chokidar which relies on inotify by default. The problem? Many editors (like Vim, or Sublime in certain modes) save files by deleting the original file and writing a new one instead of modifying it. This changes the file's inode, and inotify (which monitors inodes) doesn't pick up the change.

The Fix: Enable Polling Mode #

To work around this, force gulp.watch to use polling (which checks for file changes at regular intervals, instead of relying on inotify events). Add the usePolling: true option to your watch call:

const gulp = require( 'gulp' );

function sass( done ) {
  console.log( 'Success!' );
  done();
}

function watch() {
  // Enable polling to detect file replacements on Linux
  gulp.watch( 'src/style.scss', { usePolling: true }, gulp.series( sass ) );
}

exports.default = watch;
exports.sass = sass;

Test It Out #

Run npx gulp (or npx gulp watch if you keep your original export name) and modify src/style.scss with your editor. You should now see the Success! log pop up in your console whenever you save changes.

Why This Worked in Gulp 3 #

Gulp 3 used a different watch implementation that handled file replacement more gracefully out of the box. Gulp 4 switched to chokidar for better cross-platform support, but this means we have to explicitly enable polling for Linux systems where editors use destructive saves.

内容的提问来源于stack exchange，提问作者A.N.M. Saiful Islam