netdata/packaging/installer/functions.sh

# no shebang necessary - this is a library to be sourced
# SPDX-License-Identifier: GPL-3.0-or-later
# shellcheck disable=SC1091,SC1117,SC2002,SC2004,SC2034,SC2046,SC2059,SC2086,SC2129,SC2148,SC2154,SC2155,SC2162,SC2166,SC2181,SC2193

# make sure we have a UID
[ -z "${UID}" ] && UID="$(id -u)"

# -----------------------------------------------------------------------------

setup_terminal() {
	TPUT_RESET=""
	TPUT_BLACK=""
	TPUT_RED=""
	TPUT_GREEN=""
	TPUT_YELLOW=""
	TPUT_BLUE=""
	TPUT_PURPLE=""
	TPUT_CYAN=""
	TPUT_WHITE=""
	TPUT_BGBLACK=""
	TPUT_BGRED=""
	TPUT_BGGREEN=""
	TPUT_BGYELLOW=""
	TPUT_BGBLUE=""
	TPUT_BGPURPLE=""
	TPUT_BGCYAN=""
	TPUT_BGWHITE=""
	TPUT_BOLD=""
	TPUT_DIM=""
	TPUT_UNDERLINED=""
	TPUT_BLINK=""
	TPUT_INVERTED=""
	TPUT_STANDOUT=""
	TPUT_BELL=""
	TPUT_CLEAR=""

	# Is stderr on the terminal? If not, then fail
	test -t 2 || return 1

	if command -v tput 1>/dev/null 2>&1; then
		if [ $(($(tput colors 2>/dev/null))) -ge 8 ]; then
			# Enable colors
			TPUT_RESET="$(tput sgr 0)"
			TPUT_BLACK="$(tput setaf 0)"
			TPUT_RED="$(tput setaf 1)"
			TPUT_GREEN="$(tput setaf 2)"
			TPUT_YELLOW="$(tput setaf 3)"
			TPUT_BLUE="$(tput setaf 4)"
			TPUT_PURPLE="$(tput setaf 5)"
			TPUT_CYAN="$(tput setaf 6)"
			TPUT_WHITE="$(tput setaf 7)"
			TPUT_BGBLACK="$(tput setab 0)"
			TPUT_BGRED="$(tput setab 1)"
			TPUT_BGGREEN="$(tput setab 2)"
			TPUT_BGYELLOW="$(tput setab 3)"
			TPUT_BGBLUE="$(tput setab 4)"
			TPUT_BGPURPLE="$(tput setab 5)"
			TPUT_BGCYAN="$(tput setab 6)"
			TPUT_BGWHITE="$(tput setab 7)"
			TPUT_BOLD="$(tput bold)"
			TPUT_DIM="$(tput dim)"
			TPUT_UNDERLINED="$(tput smul)"
			TPUT_BLINK="$(tput blink)"
			TPUT_INVERTED="$(tput rev)"
			TPUT_STANDOUT="$(tput smso)"
			TPUT_BELL="$(tput bel)"
			TPUT_CLEAR="$(tput clear)"
		fi
	fi

	return 0
}
setup_terminal || echo >/dev/null

progress() {
	echo >&2 " --- ${TPUT_DIM}${TPUT_BOLD}${*}${TPUT_RESET} --- "
}

# -----------------------------------------------------------------------------

netdata_banner() {
	local l1="  ^" \
		l2="  |.-.   .-.   .-.   .-.   .-.   .-.   .-.   .-.   .-.   .-.   .-.   .-.   .-" \
		l3="  |   '-'   '-'   '-'   '-'   '-'   '-'   '-'   '-'   '-'   '-'   '-'   '-'  " \
		l4="  +----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+--->" \
		sp="                                                                              " \
		netdata="netdata" start end msg="${*}" chartcolor="${TPUT_DIM}"

	[ ${#msg} -lt ${#netdata} ] && msg="${msg}${sp:0:$((${#netdata} - ${#msg}))}"
	[ ${#msg} -gt $((${#l2} - 20)) ] && msg="${msg:0:$((${#l2} - 23))}..."

	start="$((${#l2} / 2 - 4))"
	[ $((start + ${#msg} + 4)) -gt ${#l2} ] && start=$((${#l2} - ${#msg} - 4))
	end=$((start + ${#msg} + 4))

	echo >&2
	echo >&2 "${chartcolor}${l1}${TPUT_RESET}"
	echo >&2 "${chartcolor}${l2:0:start}${sp:0:2}${TPUT_RESET}${TPUT_BOLD}${TPUT_GREEN}${netdata}${TPUT_RESET}${chartcolor}${sp:0:$((end - start - 2 - ${#netdata}))}${l2:end:$((${#l2} - end))}${TPUT_RESET}"
	echo >&2 "${chartcolor}${l3:0:start}${sp:0:2}${TPUT_RESET}${TPUT_BOLD}${TPUT_CYAN}${msg}${TPUT_RESET}${chartcolor}${sp:0:2}${l3:end:$((${#l2} - end))}${TPUT_RESET}"
	echo >&2 "${chartcolor}${l4}${TPUT_RESET}"
	echo >&2
}

# -----------------------------------------------------------------------------
# portable service command

service_cmd="$(command -v service 2>/dev/null)"
rcservice_cmd="$(command -v rc-service 2>/dev/null)"
systemctl_cmd="$(command -v systemctl 2>/dev/null)"
service() {

	local cmd="${1}" action="${2}"

	if [ -n "${systemctl_cmd}" ]; then
		run "${systemctl_cmd}" "${action}" "${cmd}"
		return $?
	elif [ -n "${service_cmd}" ]; then
		run "${service_cmd}" "${cmd}" "${action}"
		return $?
	elif [ -n "${rcservice_cmd}" ]; then
		run "${rcservice_cmd}" "${cmd}" "${action}"
		return $?
	fi
	return 1
}

# -----------------------------------------------------------------------------
# portable pidof

safe_pidof() {
	local pidof_cmd="$(command -v pidof 2>/dev/null)"
	if [ -n "${pidof_cmd}" ]; then
		${pidof_cmd} "${@}"
		return $?
	else
		ps -acxo pid,comm |
			sed "s/^ *//g" |
			grep netdata |
			cut -d ' ' -f 1
		return $?
	fi
}

# -----------------------------------------------------------------------------
find_processors() {
	local cpus
	if [ -f "/proc/cpuinfo" ]; then
		# linux
		cpus=$(grep -c ^processor /proc/cpuinfo)
	else
		# freebsd
		cpus=$(sysctl hw.ncpu 2>/dev/null | grep ^hw.ncpu | cut -d ' ' -f 2)
	fi
	if [ -z "${cpus}" ] || [ $((cpus)) -lt 1 ]; then
		echo 1
	else
		echo "${cpus}"
	fi
}

# -----------------------------------------------------------------------------
fatal() {
	printf >&2 "${TPUT_BGRED}${TPUT_WHITE}${TPUT_BOLD} ABORTED ${TPUT_RESET} ${*} \n\n"
	exit 1
}

run_ok() {
	printf >&2 "${TPUT_BGGREEN}${TPUT_WHITE}${TPUT_BOLD} OK ${TPUT_RESET} ${*} \n\n"
}

run_failed() {
	printf >&2 "${TPUT_BGRED}${TPUT_WHITE}${TPUT_BOLD} FAILED ${TPUT_RESET} ${*} \n\n"
}

ESCAPED_PRINT_METHOD=
printf "%q " test >/dev/null 2>&1
[ $? -eq 0 ] && ESCAPED_PRINT_METHOD="printfq"
escaped_print() {
	if [ "${ESCAPED_PRINT_METHOD}" = "printfq" ]; then
		printf "%q " "${@}"
	else
		printf "%s" "${*}"
	fi
	return 0
}

run_logfile="/dev/null"
run() {
	local user="${USER--}" dir="${PWD}" info info_console

	if [ "${UID}" = "0" ]; then
		info="[root ${dir}]# "
		info_console="[${TPUT_DIM}${dir}${TPUT_RESET}]# "
	else
		info="[${user} ${dir}]$ "
		info_console="[${TPUT_DIM}${dir}${TPUT_RESET}]$ "
	fi

	printf >>"${run_logfile}" "${info}"
	escaped_print >>"${run_logfile}" "${@}"
	printf >>"${run_logfile}" " ... "

	printf >&2 "${info_console}${TPUT_BOLD}${TPUT_YELLOW}"
	escaped_print >&2 "${@}"
	printf >&2 "${TPUT_RESET}\n"

	"${@}"

	local ret=$?
	if [ ${ret} -ne 0 ]; then
		run_failed
		printf >>"${run_logfile}" "FAILED with exit code ${ret}\n"
	else
		run_ok
		printf >>"${run_logfile}" "OK\n"
	fi

	return ${ret}
}

iscontainer() {
	# man systemd-detect-virt
	local cmd=$(command -v systemd-detect-virt 2>/dev/null)
	if [ -n "${cmd}" ] && [ -x "${cmd}" ]; then
		"${cmd}" --container >/dev/null 2>&1 && return 0
	fi

	# /proc/1/sched exposes the host's pid of our init !
	# http://stackoverflow.com/a/37016302
	local pid=$(cat /proc/1/sched 2>/dev/null | head -n 1 | {
		IFS='(),#:' read name pid th threads
		echo "$pid"
	})
	if [ -n "${pid}" ]; then
		pid=$(( pid + 0 ))
		[ ${pid} -gt 1 ] && return 0
	fi

	# lxc sets environment variable 'container'
	[ -n "${container}" ] && return 0

	# docker creates /.dockerenv
	# http://stackoverflow.com/a/25518345
	[ -f "/.dockerenv" ] && return 0

	# ubuntu and debian supply /bin/running-in-container
	# https://www.apt-browse.org/browse/ubuntu/trusty/main/i386/upstart/1.12.1-0ubuntu4/file/bin/running-in-container
	if [ -x "/bin/running-in-container" ]; then
		"/bin/running-in-container" >/dev/null 2>&1 && return 0
	fi

	return 1
}

issystemd() {
	local pids p myns ns systemctl

	# if the directory /lib/systemd/system OR /usr/lib/systemd/system (SLES 12.x) does not exit, it is not systemd
	[ ! -d /lib/systemd/system -a ! -d /usr/lib/systemd/system ] && return 1

	# if there is no systemctl command, it is not systemd
	# shellcheck disable=SC2230
	systemctl=$(command -v systemctl 2>/dev/null)
	[ -z "${systemctl}" -o ! -x "${systemctl}" ] && return 1

	# if pid 1 is systemd, it is systemd
	[ "$(basename $(readlink /proc/1/exe) 2>/dev/null)" = "systemd" ] && return 0

	# if systemd is not running, it is not systemd
	pids=$(safe_pidof systemd 2>/dev/null)
	[ -z "${pids}" ] && return 1

	# check if the running systemd processes are not in our namespace
	myns="$(readlink /proc/self/ns/pid 2>/dev/null)"
	for p in ${pids}; do
		ns="$(readlink "/proc/${p}/ns/pid" 2>/dev/null)"

		# if pid of systemd is in our namespace, it is systemd
		[ -n "${myns}" ] && [ "${myns}" = "${ns}" ] && return 0
	done

	# else, it is not systemd
	return 1
}

install_non_systemd_init() {
	[ "${UID}" != 0 ] && return 1

	local key="unknown"
	if [ -f /etc/os-release ]; then
		source /etc/os-release || return 1
		key="${ID}-${VERSION_ID}"

	elif [ -f /etc/redhat-release ]; then
		key=$(</etc/redhat-release)
	fi

	if [ -d /etc/init.d ] && [ ! -f /etc/init.d/netdata ]; then
		if [[ ${key} =~ ^(gentoo|alpine).* ]]; then
			echo >&2 "Installing OpenRC init file..."
			run cp system/netdata-openrc /etc/init.d/netdata &&
				run chmod 755 /etc/init.d/netdata &&
				run rc-update add netdata default &&
				return 0

		elif [ "${key}" =~ ^devuan* ] || [ "${key}" = "debian-7" ] || [ "${key}" = "ubuntu-12.04" ] || [ "${key}" = "ubuntu-14.04" ]; then
			echo >&2 "Installing LSB init file..."
			run cp system/netdata-lsb /etc/init.d/netdata &&
				run chmod 755 /etc/init.d/netdata &&
				run update-rc.d netdata defaults &&
				run update-rc.d netdata enable &&
				return 0
		elif [[ ${key} =~ ^(amzn-201[5678]|ol|CentOS release 6|Red Hat Enterprise Linux Server release 6|Scientific Linux CERN SLC release 6|CloudLinux Server release 6).* ]]; then
			echo >&2 "Installing init.d file..."
			run cp system/netdata-init-d /etc/init.d/netdata &&
				run chmod 755 /etc/init.d/netdata &&
				run chkconfig netdata on &&
				return 0
		else
			echo >&2 "I don't know what init file to install on system '${key}'. Open a github issue to help us fix it."
			return 1
		fi
	elif [ -f /etc/init.d/netdata ]; then
		echo >&2 "file '/etc/init.d/netdata' already exists."
		return 0
	else
		echo >&2 "I don't know what init file to install on system '${key}'. Open a github issue to help us fix it."
	fi

	return 1
}

NETDATA_START_CMD="netdata"
NETDATA_STOP_CMD="killall netdata"
NETDATA_INSTALLER_START_CMD="${NETDATA_START_CMD}"
NETDATA_INSTALLER_STOP_CMD="${NETDATA_STOP_CMD}"

install_netdata_service() {
	local uname="$(uname 2>/dev/null)"

	if [ "${UID}" -eq 0 ]; then
		if [ "${uname}" = "Darwin" ]; then

			if [ -f "/Library/LaunchDaemons/com.github.netdata.plist" ]; then
				echo >&2 "file '/Library/LaunchDaemons/com.github.netdata.plist' already exists."
				return 0
			else
				echo >&2 "Installing MacOS X plist file..."
				run cp system/netdata.plist /Library/LaunchDaemons/com.github.netdata.plist &&
					run launchctl load /Library/LaunchDaemons/com.github.netdata.plist &&
					return 0
			fi

		elif [ "${uname}" = "FreeBSD" ]; then

			run cp system/netdata-freebsd /etc/rc.d/netdata && NETDATA_START_CMD="service netdata start" &&
									   NETDATA_STOP_CMD="service netdata stop" &&
									   NETDATA_INSTALLER_START_CMD="service netdata onestart" &&
									   NETDATA_INSTALLER_STOP_CMD="${NETDATA_STOP_CMD}"
			myret=$?

			echo >&2 "Note: To explicitly enable netdata automatic start, set 'netdata_enable' to 'YES' in /etc/rc.conf"
			echo >&2 ""

			return ${myret}

		elif issystemd; then
			# systemd is running on this system
			NETDATA_START_CMD="systemctl start netdata"
			NETDATA_STOP_CMD="systemctl stop netdata"
			NETDATA_INSTALLER_START_CMD="${NETDATA_START_CMD}"
			NETDATA_INSTALLER_STOP_CMD="${NETDATA_STOP_CMD}"

			SYSTEMD_DIRECTORY=""

			if [ -d "/lib/systemd/system" ]; then
				SYSTEMD_DIRECTORY="/lib/systemd/system"
			elif [ -d "/usr/lib/systemd/system" ]; then
				SYSTEMD_DIRECTORY="/usr/lib/systemd/system"
			fi

			if [ "${SYSTEMD_DIRECTORY}x" != "x" ]; then
				ENABLE_NETDATA_IF_PREVIOUSLY_ENABLED="run systemctl enable netdata"
				IS_NETDATA_ENABLED="$(systemctl is-enabled netdata 2> /dev/null || echo "Netdata not there")"
				if [ "${IS_NETDATA_ENABLED}" == "disabled" ]; then
					echo >&2 "Netdata was there and disabled, make sure we don't re-enable it ourselves"
					ENABLE_NETDATA_IF_PREVIOUSLY_ENABLED="true"
				fi

				echo >&2 "Installing systemd service..."
				run cp system/netdata.service "${SYSTEMD_DIRECTORY}/netdata.service" &&
					run systemctl daemon-reload &&
					${ENABLE_NETDATA_IF_PREVIOUSLY_ENABLED} &&
					return 0
			else
				echo >&2 "no systemd directory; cannot install netdata.service"
			fi
		else
			install_non_systemd_init
			local ret=$?

			if [ ${ret} -eq 0 ]; then
				if [ -n "${service_cmd}" ]; then
					NETDATA_START_CMD="service netdata start"
					NETDATA_STOP_CMD="service netdata stop"
				elif [ -n "${rcservice_cmd}" ]; then
					NETDATA_START_CMD="rc-service netdata start"
					NETDATA_STOP_CMD="rc-service netdata stop"
				fi
				NETDATA_INSTALLER_START_CMD="${NETDATA_START_CMD}"
				NETDATA_INSTALLER_STOP_CMD="${NETDATA_STOP_CMD}"
			fi

			return ${ret}
		fi
	fi

	return 1
}

# -----------------------------------------------------------------------------
# stop netdata

pidisnetdata() {
	if [ -d /proc/self ]; then
		[ -z "$1" -o ! -f "/proc/$1/stat" ] && return 1
		[ "$(cat "/proc/$1/stat" | cut -d '(' -f 2 | cut -d ')' -f 1)" = "netdata" ] && return 0
		return 1
	fi
	return 0
}

stop_netdata_on_pid() {
	local pid="${1}" ret=0 count=0

	pidisnetdata "${pid}" || return 0

	printf >&2 "Stopping netdata on pid %s ..." "${pid}"
	while [ -n "$pid" ] && [ ${ret} -eq 0 ]; do
		if [ ${count} -gt 45 ]; then
			echo >&2 "Cannot stop the running netdata on pid ${pid}."
			return 1
		fi

		count=$((count + 1))

		run kill "${pid}" 2>/dev/null
		ret=$?

		test ${ret} -eq 0 && printf >&2 "." && sleep 2

	done

	echo >&2
	if [ ${ret} -eq 0 ]; then
		echo >&2 "SORRY! CANNOT STOP netdata ON PID ${pid} !"
		return 1
	fi

	echo >&2 "netdata on pid ${pid} stopped."
	return 0
}

netdata_pids() {
	local p myns ns

	myns="$(readlink /proc/self/ns/pid 2>/dev/null)"

	for p in \
		$(cat /var/run/netdata.pid 2>/dev/null) \
		$(cat /var/run/netdata/netdata.pid 2>/dev/null) \
		$(safe_pidof netdata 2>/dev/null); do
		ns="$(readlink "/proc/${p}/ns/pid" 2>/dev/null)"

		if [ -z "${myns}" ] || [ -z "${ns}" ] || [ "${myns}" = "${ns}" ]; then
			pidisnetdata "${p}" && echo "${p}"
		fi
	done
}

stop_all_netdata() {
	local p
	for p in $(netdata_pids); do
		# shellcheck disable=SC2086
		stop_netdata_on_pid ${p}
	done
}

# -----------------------------------------------------------------------------
# restart netdata

restart_netdata() {
	local netdata="${1}"
	shift

	local started=0

	progress "Restarting netdata instance"

	if [ "${UID}" -eq 0 ]; then
		echo >&2
		echo >&2 "Stopping all netdata threads"
		run stop_all_netdata

		echo >&2 "Starting netdata using command '${NETDATA_INSTALLER_START_CMD}'"
		run ${NETDATA_INSTALLER_START_CMD} && started=1

		if [ ${started} -eq 1 ] && [ -z "$(netdata_pids)" ]; then
			echo >&2 "Ooops! it seems netdata is not started."
			started=0
		fi

		if [ ${started} -eq 0 ]; then
			echo >&2 "Attempting another netdata start using command '${NETDATA_INSTALLER_START_CMD}'"
			run ${NETDATA_INSTALLER_START_CMD} && started=1
		fi
	fi

	if [ ${started} -eq 1 ] && [ -z "$(netdata_pids)" ]; then
		echo >&2 "Hm... it seems netdata is still not started."
		started=0
	fi

	if [ ${started} -eq 0 ]; then
		# still not started... another forced attempt, just run the binary
		echo >&2 "Netdata service still not started, attempting another forced restart by running '${netdata} ${@}'"
		run stop_all_netdata
		run "${netdata}" "${@}"
		return $?
	fi

	return 0
}

# -----------------------------------------------------------------------------
# install netdata logrotate

install_netdata_logrotate() {
	if [ "${UID}" -eq 0 ]; then
		if [ -d /etc/logrotate.d ]; then
			if [ ! -f /etc/logrotate.d/netdata ]; then
				run cp system/netdata.logrotate /etc/logrotate.d/netdata
			fi

			if [ -f /etc/logrotate.d/netdata ]; then
				run chmod 644 /etc/logrotate.d/netdata
			fi

			return 0
		fi
	fi

	return 1
}

# -----------------------------------------------------------------------------
# create netdata.conf

create_netdata_conf() {
	local path="${1}" url="${2}"

	if [ -s "${path}" ]; then
		return 0
	fi

	if [ -n "$url" ]; then
		echo >&2 "Downloading default configuration from netdata..."
		sleep 5

		# remove a possibly obsolete configuration file
		[ -f "${path}.new" ] && rm "${path}.new"

		# disable a proxy to get data from the local netdata
		export http_proxy=
		export https_proxy=

		if command -v curl 1>/dev/null 2>&1; then
			run curl -sSL --connect-timeout 10 --retry 3 "${url}" >"${path}.new"
		elif command -v wget 1>/dev/null 2>&1; then
			run wget -T 15 -O - "${url}" >"${path}.new"
		fi

		if [ -s "${path}.new" ]; then
			run mv "${path}.new" "${path}"
			run_ok "New configuration saved for you to edit at ${path}"
		else
			[ -f "${path}.new" ] && rm "${path}.new"
			run_failed "Cannnot download configuration from netdata daemon using url '${url}'"
			url=''
		fi
	fi

	if [ -z "$url" ]; then
		echo "# netdata can generate its own config which is available at 'http://<netdata_ip>/netdata.conf'" >"${path}"
		echo "# You can download it with command like: 'wget -O ${path} http://localhost:19999/netdata.conf'" >>"${path}"
	fi

}

portable_add_user() {
	local username="${1}" homedir="${2}"

	[ -z "${homedir}" ] && homedir="/tmp"

    # Check if user exists
	if cut -d ':' -f 1 </etc/passwd | grep "^${username}$" 1>/dev/null 2>&1; then
        echo >&2 "User '${username}' already exists."
        return 0
    fi

	echo >&2 "Adding ${username} user account with home ${homedir} ..."

	# shellcheck disable=SC2230
	local nologin="$(command -v nologin >/dev/null 2>&1 || echo '/bin/false')"

	# Linux
	if command -v useradd 1>/dev/null 2>&1; then
		run useradd -r -g "${username}" -c "${username}" -s "${nologin}" --no-create-home -d "${homedir}" "${username}" && return 0
	fi

	# FreeBSD
	if command -v pw 1>/dev/null 2>&1; then
		run pw useradd "${username}" -d "${homedir}" -g "${username}" -s "${nologin}" && return 0
	fi

	# BusyBox
	if command -v adduser 1>/dev/null 2>&1; then
		run adduser -h "${homedir}" -s "${nologin}" -D -G "${username}" "${username}" && return 0
	fi

	# mac OS
	if command -v sysadminctl 1> /dev/null 2>&1; then
		run sysadminctl -addUser  ${username} && return 0
	fi

	echo >&2 "Failed to add ${username} user account !"

	return 1
}

portable_add_group() {
	local groupname="${1}"

	# Check if group exist
	if cut -d ':' -f 1 </etc/group | grep "^${groupname}$" 1>/dev/null 2>&1; then
		echo >&2 "Group '${groupname}' already exists."
		return 0
	fi

	echo >&2 "Adding ${groupname} user group ..."

	# Linux
	if command -v groupadd 1>/dev/null 2>&1; then
		run groupadd -r "${groupname}" && return 0
	fi

	# FreeBSD
	if command -v pw 1>/dev/null 2>&1; then
		run pw groupadd "${groupname}" && return 0
	fi

	# BusyBox
	if command -v addgroup 1>/dev/null 2>&1; then
		run addgroup "${groupname}" && return 0
	fi

	# mac OS
	if command -v dseditgroup 1> /dev/null 2>&1; then
		dseditgroup -o create "${groupname}" && return 0
	fi

	echo >&2 "Failed to add ${groupname} user group !"
	return 1
}

portable_add_user_to_group() {
	local groupname="${1}" username="${2}"

	# Check if group exist
	if ! cut -d ':' -f 1 </etc/group | grep "^${groupname}$" >/dev/null 2>&1; then
		echo >&2 "Group '${groupname}' does not exist."
		return 1
	fi

	# Check if user is in group
	if [[ ",$(grep "^${groupname}:" </etc/group | cut -d ':' -f 4)," =~ ,${username}, ]]; then
		# username is already there
		echo >&2 "User '${username}' is already in group '${groupname}'."
		return 0
	else
		# username is not in group
		echo >&2 "Adding ${username} user to the ${groupname} group ..."

		# Linux
		if command -v usermod 1>/dev/null 2>&1; then
			run usermod -a -G "${groupname}" "${username}" && return 0
		fi

		# FreeBSD
		if command -v pw 1>/dev/null 2>&1; then
			run pw groupmod "${groupname}" -m "${username}" && return 0
		fi

		# BusyBox
		if command -v addgroup 1>/dev/null 2>&1; then
			run addgroup "${username}" "${groupname}" && return 0
		fi

		# mac OS
		if command -v dseditgroup 1> /dev/null 2>&1; then
			dseditgroup -u "${username}" "${groupname}" && return 0
		fi
		echo >&2 "Failed to add user ${username} to group ${groupname} !"
		return 1
	fi
}


safe_sha256sum() {
	# Within the contexct of the installer, we only use -c option that is common between the two commands
	# We will have to reconsider if we start non-common options
	if command -v sha256sum >/dev/null 2>&1; then
		sha256sum $@
	elif command -v shasum >/dev/null 2>&1; then
		shasum -a 256 $@
	else
		fatal "I could not find a suitable checksum binary to use"
	fi
}