[L4D2] Use squashfs to save disk. This is an script that auto mounts images and create symbolic links.

mount_maps.sh

#!/bin/bash
# To make squashfs images, run:
# $ mksquashfs *.vpk /tmp/maps.squashfs -comp xz -all-root
# xz has the best compression ratio, lz4 is faster.
# The destination system should have losetup and kmod-loop to mount squashfs in kernel.
# Run this script as root.
# Debian/Ubuntu prerequisite: apt install squashfuse
# OpenVZ: make sure /dev/fuse exists, otherwise see https://iserversupport.com/forum/virtualization/enable-fuse-on-openvz/

# Point to the L4D2 addons directory
L4D2_ADDON_DIR=

# Specifies where the VPKs and squashfs images are located
IMG_DIR=$(pwd)

# The owner of the symbolic links
OWNER=rikka

# Specifies where to mount the squashfs images
MOUNT_DIR=$(pwd)/mounts

# ln command options
LN_OPTIONS="-srv"

# Unlink old maps
for map in "$L4D2_ADDON_DIR"/*.vpk; do
        map_filename=$(basename "$map")
        echo "Unlinking $map_filename"
        unlink "$map" || true
done

# Make sure the directory exists and is empty
if [ -d "$MOUNT_DIR" ]; then
        # Attempt to unmount old mount points
        for mount_point in "$MOUNT_DIR"/*; do
                if [ -d "$mount_point" ]; then
                        umount "$mount_point" || true
                fi
        done

        # Remove old mount points and empty folders
        find "$MOUNT_DIR"/* -maxdepth 1 -type d -empty -delete 2>/dev/null

        if [[ -d "$MOUNT_DIR" && -z "$(ls -A "$MOUNT_DIR")"  ]]; then
                echo "All old mount points removed."
        else
                echo "Mount folder(\"$MOUNT_DIR\") is not empty after umount!"
                exit -1
        fi
fi

# Check if we are running the clean command only
if [[ $1 == "clean" ]]; then
        exit 0
fi

echo ""
echo "Mounting new images"
for image_path in "$IMG_DIR"/*.squashfs
do
        image_filename=$(basename -s .squashfs "$image_path")
        if [[ $image_filename == '*' ]]; then
                echo "No squashfs image (*.squashfs) found!"
                break
        fi
        echo "Mounting \"$(basename "$image_path")\":"
        mount_path="$MOUNT_DIR/$image_filename"
        sudo -u "$OWNER" mkdir -p "$mount_path"
        if squashfuse -o allow_other "$image_path" "$mount_path"; then
                sudo -u "$OWNER" ln $LN_OPTIONS "$mount_path"/*.vpk "$L4D2_ADDON_DIR"
        fi
        echo ""
done

echo ""
echo "Mount sparse maps"
find "$IMG_DIR"/*.vpk -maxdepth 1 -type f 1>/dev/null 2>/dev/null && sudo -u "$OWNER" ln $LN_OPTIONS "$IMG_DIR"/*.vpk "$L4D2_ADDON_DIR"