Atom Debian amd64 auto upgrade script

atom-update.sh

#!/bin/bash

write_log() {
	echo "${1}"
	logger -t atom-update "${1}"
}

progressfilt ()
{
	local flag=false c count cr=$'\r' nl=$'\n'
	while IFS='' read -d '' -rn 1 c
	do
		if $flag
		then
			printf '%c' "$c"
		else
			if [[ $c != $cr && $c != $nl ]]
			then
				count=0
			else
				((count++))
				if ((count > 1))
				then
					flag=true
				fi
			fi
		fi
	done
}

TMP_DIR=$(mktemp -t -d atom-update.XXXXXXXXXX 2>/dev/null) || { write_log "Failed to create temp directory"; exit 1; }
TMP_LATEST="${TMP_DIR}/latest"
TMP_FILE="${TMP_DIR}/atom-amd64.deb"

clean_up() {
	[ -d "${TMP_DIR}" ] && { write_log "Cleaning up temporary files"; rm -rf "${TMP_DIR}"; }
	exit ${1:-0}
}

trap 'clean_up 1' SIGHUP SIGINT SIGTERM

write_log "Fetching latest Atom release"

LATEST=$(curl -s -I https://github.com/atom/atom/releases/latest -w "%{redirect_url}" -o /dev/null | awk -F'/' '{ print $NF }')

VER_LATEST=$(echo "${LATEST}" | sed 's/v//g')
VER_INST=$(dpkg -l atom 2> /dev/null | tail -n1 | tr -s ' ' | cut -d" " -f 3)
VER_INST=${VER_INST:-0}

write_log "Atom currently installed version is ${VER_INST}"
write_log "Atom last downloadable version is ${VER_LATEST}"

if dpkg --compare-versions "${VER_INST}" lt "${VER_LATEST}"
then
	write_log "Get: https://github.com/atom/atom/releases/latest atom amd64 ${VER_LATEST}"

	wget --show-progress --progress=bar:force  -q \
        "https://github.com/atom/atom/releases/download/${LATEST}/atom-amd64.deb" \
        -O "${TMP_FILE}" || \
        { write_log "Can't fetch atom package"; clean_up 1; }
	VER_DOWN=$(dpkg-deb -f "${TMP_FILE}" Version)
	write_log "Atom version seen in downloaded package is ${VER_DOWN}"

	if [ "${VER_DOWN}" == "${VER_LATEST}" ]; then
		sudo dpkg -i "${TMP_FILE}"
		write_log "Atom has been updated from ${VER_INST} to ${VER_LATEST}"
	else
		write_log "Atom version seen in downloaded package differ from fetched one"
		clean_up 1
	fi
else
	write_log "Atom version ${VER_INST} is the latest version, no update required"
fi

clean_up