How to check if a program is run in Bash on Ubuntu on Windows and not just plain Ubuntu?

Question

Pretty straightforward, the usual places to figure out the OS you\'re on seem to be identical to plain Ubuntu on Ubuntu for Windows. For example uname -a is ide

Answer 1

Updating answer by @per-lundberg:

if [[ ! -z "$IS_WSL" && ! -z "$WSL_DISTRO_NAME" ]]; then
    echo "You are not in wsl!"
else
    echo "You are in wsl!"
fi

Note: IS_WSL existed in older verion while WSL_DISTRO_NAME exist in current version.