Fix issue covertsh#5: check for required commands portably

covertsh · web-flow · commit 5b93c57f05e5 · 2021-02-28T12:40:56.000Z
Use command -v to check for installed commands needed for the script. This should be more portable than checking absolute paths.
Also update the help output to show the correct names for SHA256SUM files when they are saved.
diff --git a/ubuntu-autoinstall-generator.sh b/ubuntu-autoinstall-generator.sh
@@ -2,30 +2,31 @@
 set -Eeuo pipefail
 
 function cleanup() {
-	trap - SIGINT SIGTERM ERR EXIT
-	if [ -n "${tmpdir+x}" ]; then
-		rm -rf "$tmpdir"
-		log "🚽 Deleted temporary working directory $tmpdir"
-	fi
+        trap - SIGINT SIGTERM ERR EXIT
+        if [ -n "${tmpdir+x}" ]; then
+                rm -rf "$tmpdir"
+                log "🚽 Deleted temporary working directory $tmpdir"
+        fi
 }
 
 trap cleanup SIGINT SIGTERM ERR EXIT
 script_dir=$(cd "$(dirname "${BASH_SOURCE[0]}")" &>/dev/null && pwd -P)
-today=$(/usr/bin/date +"%Y-%m-%d")
+[[ ! -x "$(command -v date)" ]] && echo "💥 date command not found." && exit 1
+today=$(date +"%Y-%m-%d")
 
 function log() {
-	echo >&2 -e "[$(date +"%Y-%m-%d %H:%M:%S")] ${1-}"
+        echo >&2 -e "[$(date +"%Y-%m-%d %H:%M:%S")] ${1-}"
 }
 
 function die() {
-	local msg=$1
-	local code=${2-1} # Bash parameter expansion - default exit status 1. See https://wiki.bash-hackers.org/syntax/pe#use_a_default_value
-	log "$msg"
-	exit "$code"
+        local msg=$1
+        local code=${2-1} # Bash parameter expansion - default exit status 1. See https://wiki.bash-hackers.org/syntax/pe#use_a_default_value
+        log "$msg"
+        exit "$code"
 }
 
 usage() {
-	cat <<EOF
+        cat <<EOF
 Usage: $(basename "${BASH_SOURCE[0]}") [-h] [-v] [-a] [-u user-data-file] [-m meta-data-file]
 
 💁 This script will create fully-automated Ubuntu 20.04 Focal Fossa installation media.
@@ -40,8 +41,8 @@ Available options:
                     For more information see: https://ubuntu.com/server/docs/install/autoinstall-quickstart
 -u, --user-data     Path to user-data file. Required if using -a
 -m, --meta-data     Path to meta-data file. Will be an empty file if not specified and using -a
--k, --no-verify     Disable GPG verification of the source ISO file. By default SHA256SUMS and
-                    SHA256SUMS.gpg in ${script_dir} will be used to verify the authenticity and integrity
+-k, --no-verify     Disable GPG verification of the source ISO file. By default SHA256SUMS-$today and
+                    SHA256SUMS-$today.gpg in ${script_dir} will be used to verify the authenticity and integrity
                     of the source ISO file. If they are not present the latest daily SHA256SUMS will be
                     downloaded and saved in ${script_dir}. The Ubuntu signing key will be downloaded and
                     saved in a new keyring in ${script_dir}
@@ -51,63 +52,63 @@ Available options:
 -d, --destination   Destination ISO file. By default ${script_dir}/ubuntu-autoinstall-$today.iso will be
                     created, overwriting any existing file.
 EOF
-	exit
+        exit
 }
 
 function parse_params() {
-	# default values of variables set from params
-	user_data_file=''
-	meta_data_file=''
-	source_iso="${script_dir}/ubuntu-original-$today.iso"
-	destination_iso="${script_dir}/ubuntu-autoinstall-$today.iso"
-	gpg_verify=1
-	all_in_one=0
-
-	while :; do
-		case "${1-}" in
-		-h | --help) usage ;;
-		-v | --verbose) set -x ;;
-		-a | --all-in-one) all_in_one=1 ;;
-		-k | --no-verify) gpg_verify=0 ;;
-		-u | --user-data)
-			user_data_file="${2-}"
-			shift
-			;;
-		-s | --source)
-			source_iso="${2-}"
-			shift
-			;;
-		-d | --destination)
-			destination_iso="${2-}"
-			shift
-			;;
-		-m | --meta-data)
-			meta_data_file="${2-}"
-			shift
-			;;
-		-?*) die "Unknown option: $1" ;;
-		*) break ;;
-		esac
-		shift
-	done
-
-	log "👶 Starting up..."
-
-	# check required params and arguments
-	if [ ${all_in_one} -ne 0 ]; then
-		[[ -z "${user_data_file}" ]] && die "💥 user-data file was not specified."
-		[[ ! -f "$user_data_file" ]] && die "💥 user-data file could not be found."
-		[[ -n "${meta_data_file}" ]] && [[ ! -f "$meta_data_file" ]] && die "💥 meta-data file could not be found."
-	fi
-
-	if [ "${source_iso}" != "${script_dir}/ubuntu-original-$today.iso" ]; then
-		[[ ! -f "${source_iso}" ]] && die "💥 Source ISO file could not be found."
-	fi
-
-	destination_iso=$(realpath "${destination_iso}")
-	source_iso=$(realpath "${source_iso}")
-
-	return 0
+        # default values of variables set from params
+        user_data_file=''
+        meta_data_file=''
+        source_iso="${script_dir}/ubuntu-original-$today.iso"
+        destination_iso="${script_dir}/ubuntu-autoinstall-$today.iso"
+        gpg_verify=1
+        all_in_one=0
+
+        while :; do
+                case "${1-}" in
+                -h | --help) usage ;;
+                -v | --verbose) set -x ;;
+                -a | --all-in-one) all_in_one=1 ;;
+                -k | --no-verify) gpg_verify=0 ;;
+                -u | --user-data)
+                        user_data_file="${2-}"
+                        shift
+                        ;;
+                -s | --source)
+                        source_iso="${2-}"
+                        shift
+                        ;;
+                -d | --destination)
+                        destination_iso="${2-}"
+                        shift
+                        ;;
+                -m | --meta-data)
+                        meta_data_file="${2-}"
+                        shift
+                        ;;
+                -?*) die "Unknown option: $1" ;;
+                *) break ;;
+                esac
+                shift
+        done
+
+        log "👶 Starting up..."
+
+        # check required params and arguments
+        if [ ${all_in_one} -ne 0 ]; then
+                [[ -z "${user_data_file}" ]] && die "💥 user-data file was not specified."
+                [[ ! -f "$user_data_file" ]] && die "💥 user-data file could not be found."
+                [[ -n "${meta_data_file}" ]] && [[ ! -f "$meta_data_file" ]] && die "💥 meta-data file could not be found."
+        fi
+
+        if [ "${source_iso}" != "${script_dir}/ubuntu-original-$today.iso" ]; then
+                [[ ! -f "${source_iso}" ]] && die "💥 Source ISO file could not be found."
+        fi
+
+        destination_iso=$(realpath "${destination_iso}")
+        source_iso=$(realpath "${source_iso}")
+
+        return 0
 }
 
 ubuntu_gpg_key_id="843938DF228D22F7B3742BC0D94AA3F0EFE21092"
@@ -117,105 +118,105 @@ parse_params "$@"
 tmpdir=$(mktemp -d)
 
 if [[ ! "$tmpdir" || ! -d "$tmpdir" ]]; then
-	die "💥 Could not create temporary working directory."
+        die "💥 Could not create temporary working directory."
 else
-	log "📁 Created temporary working directory $tmpdir"
+        log "📁 Created temporary working directory $tmpdir"
 fi
 
 log "🔎 Checking for required utilities..."
-[[ ! -f "/usr/bin/7z" ]] && die "💥 7z is not installed."
-[[ ! -f "/usr/bin/sed" ]] && die "💥 sed is not installed."
-[[ ! -f "/usr/bin/curl" ]] && die "💥 curl is not installed."
-[[ ! -f "/usr/bin/mkisofs" ]] && die "💥 mkisofs is not installed."
-[[ ! -f "/usr/bin/gpg" ]] && die "💥 gpg is not installed."
+[[ ! -x "$(command -v 7z)" ]] && die "💥 7z is not installed."
+[[ ! -x "$(command -v sed)" ]] && die "💥 sed is not installed."
+[[ ! -x "$(command -v curl)" ]] && die "💥 curl is not installed."
+[[ ! -x "$(command -v mkisofs)" ]] && die "💥 mkisofs is not installed."
+[[ ! -x "$(command -v gpg)" ]] && die "💥 gpg is not installed."
 log "👍 All required utilities are installed."
 
 if [ ! -f "${source_iso}" ]; then
-	log "🌎 Downloading current daily ISO image for Ubuntu 20.04 Focal Fossa..."
-	/usr/bin/curl -NsSL "https://cdimage.ubuntu.com/ubuntu-server/focal/daily-live/current/focal-live-server-amd64.iso" -o "${source_iso}"
-	log "👍 Downloaded and saved to ${source_iso}"
+        log "🌎 Downloading current daily ISO image for Ubuntu 20.04 Focal Fossa..."
+        curl -NsSL "https://cdimage.ubuntu.com/ubuntu-server/focal/daily-live/current/focal-live-server-amd64.iso" -o "${source_iso}"
+        log "👍 Downloaded and saved to ${source_iso}"
 else
-	log "☑️ Using existing ${source_iso} file."
-	if [ ${gpg_verify} -eq 1 ]; then
-		if [ "${source_iso}" != "${script_dir}/ubuntu-original-$today.iso" ]; then
-			log "⚠️ Automatic GPG verification is enabled. If the source ISO file is not the latest daily image, verification will fail!"
-		fi
-	fi
+        log "☑️ Using existing ${source_iso} file."
+        if [ ${gpg_verify} -eq 1 ]; then
+                if [ "${source_iso}" != "${script_dir}/ubuntu-original-$today.iso" ]; then
+                        log "⚠️ Automatic GPG verification is enabled. If the source ISO file is not the latest daily image, verification will fail!"
+                fi
+        fi
 fi
 
 if [ ${gpg_verify} -eq 1 ]; then
-	if [ ! -f "${script_dir}/SHA256SUMS-${today}" ]; then
-		log "🌎 Downloading SHA256SUMS & SHA256SUMS.gpg files..."
-		/usr/bin/curl -NsSL "https://cdimage.ubuntu.com/ubuntu-server/focal/daily-live/current/SHA256SUMS" -o "${script_dir}/SHA256SUMS-${today}"
-		/usr/bin/curl -NsSL "https://cdimage.ubuntu.com/ubuntu-server/focal/daily-live/current/SHA256SUMS.gpg" -o "${script_dir}/SHA256SUMS-${today}.gpg"
-	else
-		log "☑️ Using existing SHA256SUMS-${today} & SHA256SUMS-${today}.gpg files."
-	fi
-
-	if [ ! -f "${script_dir}/${ubuntu_gpg_key_id}.keyring" ]; then
-		log "🌎 Downloading and saving Ubuntu signing key..."
-		/usr/bin/gpg -q --no-default-keyring --keyring "${script_dir}/${ubuntu_gpg_key_id}.keyring" --keyserver "hkp://keyserver.ubuntu.com" --recv-keys "${ubuntu_gpg_key_id}"
-		log "👍 Downloaded and saved to ${script_dir}/${ubuntu_gpg_key_id}.keyring"
-	else
-		log "☑️ Using existing Ubuntu signing key saved in ${script_dir}/${ubuntu_gpg_key_id}.keyring"
-	fi
-
-	log "🔐 Verifying ${source_iso} integrity and authenticity..."
-	/usr/bin/gpg -q --keyring "${script_dir}/${ubuntu_gpg_key_id}.keyring" --verify "${script_dir}/SHA256SUMS-${today}.gpg" "${script_dir}/SHA256SUMS-${today}" 2>/dev/null
-	if [ $? -ne 0 ]; then
-		rm -f "${script_dir}/${ubuntu_gpg_key_id}.keyring~"
-		die "👿 Verification of SHA256SUMS signature failed."
-	fi
-
-	rm -f "${script_dir}/${ubuntu_gpg_key_id}.keyring~"
-	digest=$(sha256sum "${source_iso}" | cut -f1 -d ' ')
-	set +e
-	/usr/bin/grep -Fq "$digest" "${script_dir}/SHA256SUMS-${today}"
-	if [ $? -eq 0 ]; then
-		log "👍 Verification succeeded."
-		set -e
-	else
-		die "👿 Verification of ISO digest failed."
-	fi
+        if [ ! -f "${script_dir}/SHA256SUMS-${today}" ]; then
+                log "🌎 Downloading SHA256SUMS & SHA256SUMS.gpg files..."
+                curl -NsSL "https://cdimage.ubuntu.com/ubuntu-server/focal/daily-live/current/SHA256SUMS" -o "${script_dir}/SHA256SUMS-${today}"
+                curl -NsSL "https://cdimage.ubuntu.com/ubuntu-server/focal/daily-live/current/SHA256SUMS.gpg" -o "${script_dir}/SHA256SUMS-${today}.gpg"
+        else
+                log "☑️ Using existing SHA256SUMS-${today} & SHA256SUMS-${today}.gpg files."
+        fi
+
+        if [ ! -f "${script_dir}/${ubuntu_gpg_key_id}.keyring" ]; then
+                log "🌎 Downloading and saving Ubuntu signing key..."
+                gpg -q --no-default-keyring --keyring "${script_dir}/${ubuntu_gpg_key_id}.keyring" --keyserver "hkp://keyserver.ubuntu.com" --recv-keys "${ubuntu_gpg_key_id}"
+                log "👍 Downloaded and saved to ${script_dir}/${ubuntu_gpg_key_id}.keyring"
+        else
+                log "☑️ Using existing Ubuntu signing key saved in ${script_dir}/${ubuntu_gpg_key_id}.keyring"
+        fi
+
+        log "🔐 Verifying ${source_iso} integrity and authenticity..."
+        gpg -q --keyring "${script_dir}/${ubuntu_gpg_key_id}.keyring" --verify "${script_dir}/SHA256SUMS-${today}.gpg" "${script_dir}/SHA256SUMS-${today}" 2>/dev/null
+        if [ $? -ne 0 ]; then
+                rm -f "${script_dir}/${ubuntu_gpg_key_id}.keyring~"
+                die "👿 Verification of SHA256SUMS signature failed."
+        fi
+
+        rm -f "${script_dir}/${ubuntu_gpg_key_id}.keyring~"
+        digest=$(sha256sum "${source_iso}" | cut -f1 -d ' ')
+        set +e
+        grep -Fq "$digest" "${script_dir}/SHA256SUMS-${today}"
+        if [ $? -eq 0 ]; then
+                log "👍 Verification succeeded."
+                set -e
+        else
+                die "👿 Verification of ISO digest failed."
+        fi
 else
-	log "🤞 Skipping verification of source ISO."
+        log "🤞 Skipping verification of source ISO."
 fi
 log "🔧 Extracting ISO image..."
-/usr/bin/7z -y x "${source_iso}" -o"$tmpdir" >/dev/null
+7z -y x "${source_iso}" -o"$tmpdir" >/dev/null
 rm -rf "$tmpdir/"'[BOOT]'
 log "👍 Extracted to $tmpdir"
 
 log "🧩 Adding autoinstall parameter to kernel command line..."
-/usr/bin/sed -i -e 's/---/ autoinstall  ---/g' "$tmpdir/isolinux/txt.cfg"
-/usr/bin/sed -i -e 's/---/ autoinstall  ---/g' "$tmpdir/boot/grub/grub.cfg"
-/usr/bin/sed -i -e 's/---/ autoinstall  ---/g' "$tmpdir/boot/grub/loopback.cfg"
+sed -i -e 's/---/ autoinstall  ---/g' "$tmpdir/isolinux/txt.cfg"
+sed -i -e 's/---/ autoinstall  ---/g' "$tmpdir/boot/grub/grub.cfg"
+sed -i -e 's/---/ autoinstall  ---/g' "$tmpdir/boot/grub/loopback.cfg"
 log "👍 Added parameter to UEFI and BIOS kernel command lines."
 
 if [ ${all_in_one} -eq 1 ]; then
-	log "🧩 Adding user-data and meta-data files..."
-	mkdir "$tmpdir/nocloud"
-	cp "$user_data_file" "$tmpdir/nocloud/user-data"
-	if [ -n "${meta_data_file}" ]; then
-		cp "$meta_data_file" "$tmpdir/nocloud/meta-data"
-	else
-		touch "$tmpdir/nocloud/meta-data"
-	fi
-	/usr/bin/sed -i -e 's,---, ds=nocloud;s=/cdrom/nocloud/  ---,g' "$tmpdir/isolinux/txt.cfg"
-	/usr/bin/sed -i -e 's,---, ds=nocloud\\\;s=/cdrom/nocloud/  ---,g' "$tmpdir/boot/grub/grub.cfg"
-	/usr/bin/sed -i -e 's,---, ds=nocloud\\\;s=/cdrom/nocloud/  ---,g' "$tmpdir/boot/grub/loopback.cfg"
-	log "👍 Added data and configured kernel command line."
+        log "🧩 Adding user-data and meta-data files..."
+        mkdir "$tmpdir/nocloud"
+        cp "$user_data_file" "$tmpdir/nocloud/user-data"
+        if [ -n "${meta_data_file}" ]; then
+                cp "$meta_data_file" "$tmpdir/nocloud/meta-data"
+        else
+                touch "$tmpdir/nocloud/meta-data"
+        fi
+        sed -i -e 's,---, ds=nocloud;s=/cdrom/nocloud/  ---,g' "$tmpdir/isolinux/txt.cfg"
+        sed -i -e 's,---, ds=nocloud\\\;s=/cdrom/nocloud/  ---,g' "$tmpdir/boot/grub/grub.cfg"
+        sed -i -e 's,---, ds=nocloud\\\;s=/cdrom/nocloud/  ---,g' "$tmpdir/boot/grub/loopback.cfg"
+        log "👍 Added data and configured kernel command line."
 fi
 
 log "👷 Updating $tmpdir/md5sum.txt with hashes of modified files..."
-md5=$(/usr/bin/md5sum "$tmpdir/boot/grub/grub.cfg" | /usr/bin/cut -f1 -d ' ')
-/usr/bin/sed -i -e 's,^.*[[:space:]] ./boot/grub/grub.cfg,'"$md5"'  ./boot/grub/grub.cfg,' "$tmpdir/md5sum.txt"
-md5=$(/usr/bin/md5sum "$tmpdir/boot/grub/loopback.cfg" | /usr/bin/cut -f1 -d ' ')
-/usr/bin/sed -i -e 's,^.*[[:space:]] ./boot/grub/loopback.cfg,'"$md5"'  ./boot/grub/loopback.cfg,' "$tmpdir/md5sum.txt"
+md5=$(md5sum "$tmpdir/boot/grub/grub.cfg" | cut -f1 -d ' ')
+sed -i -e 's,^.*[[:space:]] ./boot/grub/grub.cfg,'"$md5"'  ./boot/grub/grub.cfg,' "$tmpdir/md5sum.txt"
+md5=$(md5sum "$tmpdir/boot/grub/loopback.cfg" | cut -f1 -d ' ')
+sed -i -e 's,^.*[[:space:]] ./boot/grub/loopback.cfg,'"$md5"'  ./boot/grub/loopback.cfg,' "$tmpdir/md5sum.txt"
 log "👍 Updated hashes."
 
 log "📦 Repackaging extracted files into an ISO image..."
 cd "$tmpdir"
-/usr/bin/mkisofs -quiet -D -r -V "ubuntu-autoinstall-$today" -cache-inodes -J -l -b isolinux/isolinux.bin -c isolinux/boot.cat -no-emul-boot -boot-load-size 4 -boot-info-table -eltorito-alt-boot -e boot/grub/efi.img -no-emul-boot -o "${destination_iso}" .
+mkisofs -quiet -D -r -V "ubuntu-autoinstall-$today" -cache-inodes -J -l -b isolinux/isolinux.bin -c isolinux/boot.cat -no-emul-boot -boot-load-size 4 -boot-info-table -eltorito-alt-boot -e boot/grub/efi.img -no-emul-boot -o "${destination_iso}" .
 cd "$OLDPWD"
 log "👍 Repackaged into ${destination_iso}"
 
