DockerCLI/scripts/warn-outside-container

#!/usr/bin/env bash
set -eu

target="${1:-}"

if [[ "$target" != "help" && -z "${DISABLE_WARN_OUTSIDE_CONTAINER:-}" ]]; then
    (
        echo
        echo
        echo "WARNING: you are not in a container."
        echo "Use \"make -f docker.Makefile $target\" or set"
        echo "DISABLE_WARN_OUTSIDE_CONTAINER=1 to disable this warning."
        echo
        echo "Press Ctrl+C now to abort."
        echo
    ) >&2
    sleep 10
fi