What would be a convenient way to open Firefox in a separate, named instance which doesn't use my current preferences, whats the best way to do this?

2 Answers 2


If you specify an alternate home directory in a separate shell and run a new instance of Firefox from that same shell, that will achieve the outcome you're looking for.


export HOME=~/some_alternate_dir && exec firefox --new-instance

I use a script which does this but also gives me the option of running multiple alternate named instances of firefox (these named instances are also re-usable):

#!/usr/bin/env bash

# Check for a maximum of one arg
[ "$#" -gt 1 ] && echo "Usage: \"ffalt [alternate name]\", or;" && \
echo "\"ffalt\" to run default firefox alternate session" && exit

# Alt name = first arg; otherwise alt name = "default"
[ "$alt_name" == "" ] && alt_name="default"

# If XDG_DATA_HOME is set then use this:
# Otherwise:
[ -z ${XDG_DATA_HOME+x} ] && alt_ff_home="$HOME"/.local/share/firefox_alts/"$alt_name"

# Ensure that the firefox alternates data dir exists
! [ -d "$alt_ff_home" ] && mkdir -p "$alt_ff_home"

# This is where the magic happens
export HOME="$alt_ff_home"
exec firefox --new-instance &

Edit: Based on @xenoid's answer, you could replace the last two lines in the script above with:

exec firefox --profile "$alt_ff_home" --new-instance &

Use the --profile option to tell firefox to use another user profile:

firefox --profile /path/to/the/alternate/profile

Note that this firefox instance won't have any of you current bookmarks, saved logins, or plugins.

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .