First time poster, long time lurker, searched, couldn’t find etc, etc.

I’m running vim in tmux, in iTerm2. I’m running a server with Grunt.js, which I have running in the background, out of my way. I start my grunt server in the background like this:

grunt server &

Grunt also watches a bunch of files, and runs some tasks when any of the watched files have been written to. The problem is, when I am in vim and I write a file, the output from grunt starts rendering in vim! Here are some screenshots to illustrate the problem:

Before writing the file:

enter image description here

And after writing the file:

enter image description here

What have I tried?

I’ve tried running a ‘stock’ vim by starting with this:

vim -u NONE

…But the problem remains. This suggests to me that the problem is not with my .vimrc. Perhaps it’s an issue with iTerm2, I don’t know. Help.

  • Is the rogue text actually saved to the file and is still present when you reload it? – FreudianSlip Nov 7 '13 at 9:08
  • No, it’s cleared when vim redraws that region. I noticed this after disabling lazyredraw, and moving the cursorline over the artefacts. – Jezen Thomas Nov 7 '13 at 10:13

Starting a process as a background one does not automatically redirect its output. So what the background process sends to stdout or stderr appears in the terminal you started the process in.


  • Redirect the output of the background process during start:
    grunt server >grunt-server.log 2>&1 &
  • Start the background process in a separate tmux session.
  • nohup automatically redirects the output to nohup.out:
    nohup grunt server &
  • if you do not need the output you can discard it:
    grunt server >/dev/null 2>&1 &

You can't fix that issue from Vim itself: grunt is just spitting stuff via stdout an that output is leaking in anything you do in that shell, Vim included. Normally, a simple <C-l> should cleanup the screen.

Either you find a way to silence grunt completely or you launch it in another iTerm pane/tab/window.

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