Firefox: Sink the Slack morgue to /dev/null to avoid disk usage

firefox-morgue-sink.sh

#!/bin/bash

# https://gist.github.com/echuber2/c85fadf936db3e0f54df4369e99dcd12

# Running Slack in Firefox creates a lot of temporary data in a "morgue"
# subdirectory of the local storage in your user profile. This doesn't seem to
# be necessary for it to function correctly, although it can eat up a lot of
# disk space (sometimes up to 1GB or more). Clearing the directory frequently
# helps but this process wastes disk writes on an SSD.

# To avoid any "morgue" items being created, you can try recreating a fake
# morgue item as a symlink to a non-existent directory or to /dev/null. I'm
# not really sure what the long-term side effects of doing this might be, but
# Slack still seems to work.

if [ "$(id -u)" -eq 0 ]; then
    echo "Don't run this as root"
    exit 1
fi

# You can find your profile directory from about:support
FF_PROFILE="$HOME/.mozilla/firefox/whatever7abcd.default"

# This part should be predictable. Make sure it matches what you already have
# on your system within the profile directory.
MORGUE_RELPATH="storage/default/https+++app.slack.com/cache/morgue"

# Doing this is in several steps to help avoid mistakes...
cd "$FF_PROFILE" || {
    echo "Wrong Firefox profile directory path. Please edit the FF_PROFILE variable in the script."
    exit 1
}
if [ ! -e "$MORGUE_RELPATH" ]; then
    mkdir -p "$MORGUE_RELPATH"
fi
rm -rfv "$MORGUE_RELPATH" || exit
echo "Linking..."
ln -sv /dev/null "$MORGUE_RELPATH" || exit

# This can happen if you try to run this script while Firefox is still open
# and the morgue is recreated before the link step. Then you would create a
# symlink called "morgue" inside the morgue directory without a clear error
# message.
if [[ "$(realpath "$MORGUE_RELPATH")" != "/dev/null" ]]; then
    echo "Error: The symlink to /dev/null was not created successfully."
    exit 1
fi

echo Done