Bash script to rename/symlink SkyrimSELauncher.exe and skse64_loader.exe to enable/disable SKSE for launch via Steam.

skse_swap.sh

#!/bin/bash

# This script manipulates SkyrimSELauncher.exe and skse64_loader.exe so that
# tools like Steam that expect to run SkyrimSELauncher.exe will transparently
# run skse64_loader.exe instead.

# When SKSE is "enabled", SkyrimSELauncher.exe will have been renamed to 
# SkyrimSELauncher.exe.orig and replaced with a symlink to skse64_loader.exe

# When SKSE is "disabled", that symlink will be named SkyrimSELauncher.exe.skse

if [ -f "SkyrimSELauncher.exe.skse" ]; then
    # skse disabled. enable it.
    mv "SkyrimSELauncher.exe" "SkyrimSELauncher.exe.orig" &&
    mv "SkyrimSELauncher.exe.skse" "SkyrimSELauncher.exe" &&
    echo "SKSE now enabled" &&
    exit 0 ||
    echo "Failed to enable SKSE" &&
    exit 1
elif [ -f "SkyrimSELauncher.exe.orig" ]; then
    # skse enabled. disable it.
    mv "SkyrimSELauncher.exe" "SkyrimSELauncher.exe.skse" &&
    mv "SkyrimSELauncher.exe.orig" "SkyrimSELauncher.exe" &&
    echo "SKSE now disabled" &&
    exit 0 ||
    echo "Failed to disable SKSE" &&
    exit 1
elif [ -f "skse64_loader.exe" ]; then
    # skse symlink not set up. set it up and enable it.
    mv "SkyrimSELauncher.exe" "SkyrimSELauncher.exe.orig" &&
    ln -s "skse64_loader.exe" "SkyrimSELauncher.exe" &&
    echo "SKSE symlink set up and enabled" &&
    exit 0 ||
    echo "Failed to set up SKSE symlink and enable it" &&
    exit 1
else
    echo "skse64_loader.exe is missing, cannot proceed"
    exit 1
fi