Running Firefox with a Temporary Profile

I was trying to book a hotel, but the somewhat-awful website wouldn’t let me complete the online purchase. I know the website is awful because it wouldn’t accept my plus-addressed email either.

Suspecting it was one of my tweaks to the privacy settings or a privacy-protecting add-on, I wanted a quick way to use the website without any of these alterations.

So, I found a very short shell script (which I’ve slightly modified) to do exactly that. It will start a fresh instance of Firefox and delete it when you are done.

# Start Firefox with a temporary profile

set -eu

PROFILEDIR=$(mktemp --tmpdir -d tmp-ff-profile.XXXXXX.d)
firefox -profile "$PROFILEDIR" -no-remote -new-instance
rm -rf "$PROFILEDIR"

It isn’t perfect because it does allow websites to use browser fingerprinting to identify you. However, this is a compromise I’m willing to make for the rare occasion that I will want to use it.

An idea that I had was to use firejail (or a similar application-sandboxer) to provide additional security. However, I suspect this blog post wouldn’t be posted this year if I went off exploring this!

This could also be useful when you do want to let websites track you across the internet. For example, when you use a cashback website that needs to track you across the shopping site.