github.com/guilhermebr/docker@v1.4.2-0.20150428121140-67da055cebca/hack/install.sh

#!/bin/sh
set -e
#
# This script is meant for quick & easy install via:
#   'curl -sSL https://get.docker.com/ | sh'
# or:
#   'wget -qO- https://get.docker.com/ | sh'
#
#
# Docker Maintainers:
#   To update this script on https://get.docker.com,
#   use hack/release.sh during a normal release,
#   or the following one-liner for script hotfixes:
#     s3cmd put --acl-public -P hack/install.sh s3://get.docker.com/index
#

url='https://get.docker.com/'

command_exists() {
	command -v "$@" > /dev/null 2>&1
}

echo_docker_as_nonroot() {
	your_user=your-user
	[ "$user" != 'root' ] && your_user="$user"
	# intentionally mixed spaces and tabs here -- tabs are stripped by "<<-EOF", spaces are kept in the output
	cat <<-EOF

	If you would like to use Docker as a non-root user, you should now consider
	adding your user to the "docker" group with something like:

	  sudo usermod -aG docker $your_user

	Remember that you will have to log out and back in for this to take effect!

	EOF
}

do_install() {
	case "$(uname -m)" in
		*64)
			;;
		*)
			cat >&2 <<-'EOF'
			Error: you are not using a 64bit platform.
			Docker currently only supports 64bit platforms.
			EOF
			exit 1
			;;
	esac

	if command_exists docker || command_exists lxc-docker; then
		cat >&2 <<-'EOF'
		Warning: "docker" or "lxc-docker" command appears to already exist.
		Please ensure that you do not already have docker installed.
		You may press Ctrl+C now to abort this process and rectify this situation.
		EOF
		( set -x; sleep 20 )
	fi

	user="$(id -un 2>/dev/null || true)"

	sh_c='sh -c'
	if [ "$user" != 'root' ]; then
		if command_exists sudo; then
			sh_c='sudo -E sh -c'
		elif command_exists su; then
			sh_c='su -c'
		else
			cat >&2 <<-'EOF'
			Error: this installer needs the ability to run commands as root.
			We are unable to find either "sudo" or "su" available to make this happen.
			EOF
			exit 1
		fi
	fi

	curl=''
	if command_exists curl; then
		curl='curl -sSL'
	elif command_exists wget; then
		curl='wget -qO-'
	elif command_exists busybox && busybox --list-modules | grep -q wget; then
		curl='busybox wget -qO-'
	fi

	# perform some very rudimentary platform detection
	lsb_dist=''
	if command_exists lsb_release; then
		lsb_dist="$(lsb_release -si)"
	fi
	if [ -z "$lsb_dist" ] && [ -r /etc/lsb-release ]; then
		lsb_dist="$(. /etc/lsb-release && echo "$DISTRIB_ID")"
	fi
	if [ -z "$lsb_dist" ] && [ -r /etc/debian_version ]; then
		lsb_dist='debian'
	fi
	if [ -z "$lsb_dist" ] && [ -r /etc/fedora-release ]; then
		lsb_dist='fedora'
	fi
	if [ -z "$lsb_dist" ] && [ -r /etc/os-release ]; then
		lsb_dist="$(. /etc/os-release && echo "$ID")"
	fi

	lsb_dist="$(echo "$lsb_dist" | tr '[:upper:]' '[:lower:]')"
	case "$lsb_dist" in
		amzn|fedora|centos)
			if [ "$lsb_dist" = 'amzn' ]; then
				(
					set -x
					$sh_c 'sleep 3; yum -y -q install docker'
				)
			else
				(
					set -x
					$sh_c 'sleep 3; yum -y -q install docker-io'
				)
			fi
			if command_exists docker && [ -e /var/run/docker.sock ]; then
				(
					set -x
					$sh_c 'docker version'
				) || true
			fi
			echo_docker_as_nonroot
			exit 0
			;;

		ubuntu|debian|linuxmint|'elementary os'|kali)
			export DEBIAN_FRONTEND=noninteractive

			did_apt_get_update=
			apt_get_update() {
				if [ -z "$did_apt_get_update" ]; then
					( set -x; $sh_c 'sleep 3; apt-get update' )
					did_apt_get_update=1
				fi
			}

			# aufs is preferred over devicemapper; try to ensure the driver is available.
			if ! grep -q aufs /proc/filesystems && ! $sh_c 'modprobe aufs'; then
				if uname -r | grep -q -- '-generic' && dpkg -l 'linux-image-*-generic' | grep -q '^ii' 2>/dev/null; then
					kern_extras="linux-image-extra-$(uname -r) linux-image-extra-virtual"

					apt_get_update
					( set -x; $sh_c 'sleep 3; apt-get install -y -q '"$kern_extras" ) || true

					if ! grep -q aufs /proc/filesystems && ! $sh_c 'modprobe aufs'; then
						echo >&2 'Warning: tried to install '"$kern_extras"' (for AUFS)'
						echo >&2 ' but we still have no AUFS.  Docker may not work. Proceeding anyways!'
						( set -x; sleep 10 )
					fi
				else
					echo >&2 'Warning: current kernel is not supported by the linux-image-extra-virtual'
					echo >&2 ' package.  We have no AUFS support.  Consider installing the packages'
					echo >&2 ' linux-image-virtual kernel and linux-image-extra-virtual for AUFS support.'
					( set -x; sleep 10 )
				fi
			fi

			# install apparmor utils if they're missing and apparmor is enabled in the kernel
			# otherwise Docker will fail to start
			if [ "$(cat /sys/module/apparmor/parameters/enabled 2>/dev/null)" = 'Y' ]; then
				if command -v apparmor_parser &> /dev/null; then
					echo 'apparmor is enabled in the kernel and apparmor utils were already installed'
				else
					echo 'apparmor is enabled in the kernel, but apparmor_parser missing'
					apt_get_update
					( set -x; $sh_c 'sleep 3; apt-get install -y -q apparmor' )
				fi
			fi

			if [ ! -e /usr/lib/apt/methods/https ]; then
				apt_get_update
				( set -x; $sh_c 'sleep 3; apt-get install -y -q apt-transport-https ca-certificates' )
			fi
			if [ -z "$curl" ]; then
				apt_get_update
				( set -x; $sh_c 'sleep 3; apt-get install -y -q curl ca-certificates' )
				curl='curl -sSL'
			fi
			(
				set -x
				if [ "https://get.docker.com/" = "$url" ]; then
					$sh_c "apt-key adv --keyserver hkp://p80.pool.sks-keyservers.net:80 --recv-keys 36A1D7869245C8950F966E92D8576A8BA88D21E9"
				elif [ "https://test.docker.com/" = "$url" ]; then
					$sh_c "apt-key adv --keyserver hkp://p80.pool.sks-keyservers.net:80 --recv-keys 740B314AE3941731B942C66ADF4FD13717AAD7D6"
				else
					$sh_c "$curl ${url}gpg | apt-key add -"
				fi
				$sh_c "echo deb ${url}ubuntu docker main > /etc/apt/sources.list.d/docker.list"
				$sh_c 'sleep 3; apt-get update; apt-get install -y -q lxc-docker'
			)
			if command_exists docker && [ -e /var/run/docker.sock ]; then
				(
					set -x
					$sh_c 'docker version'
				) || true
			fi
			echo_docker_as_nonroot
			exit 0
			;;

		gentoo)
			if [ "$url" = "https://test.docker.com/" ]; then
				# intentionally mixed spaces and tabs here -- tabs are stripped by "<<-'EOF'", spaces are kept in the output
				cat >&2 <<-'EOF'

				  You appear to be trying to install the latest nightly build in Gentoo.'
				  The portage tree should contain the latest stable release of Docker, but'
				  if you want something more recent, you can always use the live ebuild'
				  provided in the "docker" overlay available via layman.  For more'
				  instructions, please see the following URL:'

				    https://github.com/tianon/docker-overlay#using-this-overlay'

				  After adding the "docker" overlay, you should be able to:'

				    emerge -av =app-emulation/docker-9999'

				EOF
				exit 1
			fi

			(
				set -x
				$sh_c 'sleep 3; emerge app-emulation/docker'
			)
			exit 0
			;;
	esac

	# intentionally mixed spaces and tabs here -- tabs are stripped by "<<-'EOF'", spaces are kept in the output
	cat >&2 <<-'EOF'

	  Either your platform is not easily detectable, is not supported by this
	  installer script (yet - PRs welcome! [hack/install.sh]), or does not yet have
	  a package for Docker.  Please visit the following URL for more detailed
	  installation instructions:

	    https://docs.docker.com/en/latest/installation/

	EOF
	exit 1
}

# wrapped up in a function so that we have some protection against only getting
# half the file during "curl | sh"
do_install