Fix warnings reported by shellcheck

* SC2068: Double quote array expansions to avoid re-splitting elements.
* SC2186: tempfile is deprecated. Use mktemp instead.
* SC2124: Assigning an array to a string! Assign as array, or use * instead of @ to concatenate.
* SC2102: Ranges can only match single chars (mentioned due to duplicates).
* SC2005: Useless echo? Instead of 'echo $(cmd)', just use 'cmd'.

setup/functions.sh

@@ -9,12 +9,12 @@ function hide_output {
 	# and returns a non-zero exit code.
 
 	# Get a temporary file.
-	OUTPUT=$(tempfile)
+	OUTPUT=$(mktemp)
 
 	# Execute command, redirecting stderr/stdout to the temporary file. Since we
 	# check the return code ourselves, disable 'set -e' temporarily.
 	set +e
-	$@ &> $OUTPUT
+	"$@" &> $OUTPUT
 	E=$?
 	set -e
 
@@ -22,7 +22,7 @@ function hide_output {
 	if [ $E != 0 ]; then
 		# Something failed.
 		echo
-		echo FAILED: $@
+		echo FAILED: "$@"
 		echo -----------------------------------------
 		cat $OUTPUT
 		echo -----------------------------------------
@@ -53,8 +53,7 @@ function apt_install {
 	# install' for all of the packages.  Calling `dpkg` on each package is slow,
 	# and doesn't affect what we actually do, except in the messages, so let's
 	# not do that anymore.
-	PACKAGES=$@
-	apt_get_quiet install $PACKAGES
+	apt_get_quiet install "$@"
 }
 
 function get_default_hostname {

setup/mail-postfix.sh

@@ -191,7 +191,7 @@ tools/editconf.py /etc/postfix/main.cf \
 #
 # In a basic setup we would pass mail directly to Dovecot by setting
 # virtual_transport to `lmtp:unix:private/dovecot-lmtp`.
-tools/editconf.py /etc/postfix/main.cf virtual_transport=lmtp:[127.0.0.1]:10025
+tools/editconf.py /etc/postfix/main.cf "virtual_transport=lmtp:[127.0.0.1]:10025"
 # Because of a spampd bug, limit the number of recipients in each connection.
 # See https://github.com/mail-in-a-box/mailinabox/issues/1523.
 tools/editconf.py /etc/postfix/main.cf lmtp_destination_recipient_limit=1

setup/start.sh

@@ -78,7 +78,7 @@ if [ ! -d $STORAGE_ROOT ]; then
 	mkdir -p $STORAGE_ROOT
 fi
 if [ ! -f $STORAGE_ROOT/mailinabox.version ]; then
-	echo $(setup/migrate.py --current) > $STORAGE_ROOT/mailinabox.version
+	setup/migrate.py --current > $STORAGE_ROOT/mailinabox.version
 	chown $STORAGE_USER.$STORAGE_USER $STORAGE_ROOT/mailinabox.version
 fi