scripts: add os-specific requirements check

scripts/install.sh

@@ -43,14 +43,27 @@ is_little_endian() {
 # machine.  The required software (only one requirement for now):
 #
 #   curl
+#   unzip (macOS)
+#   tar (linux)
 #
 check_required() {
+	readonly spec_darwin="unzip"
+	readonly spec_linux="tar"
+
 	# Split with space.
-	readonly required="curl"
+	required="curl"
+	if [ "$os" = 'linux' ]
+	then
+		required="$required $spec_linux"
+	elif [ "$os" = 'darwin' ]
+	then
+		required="$required $spec_darwin"
+	fi
 
 	# Don't use quotes to get word splitting.
 	for cmd in ${required}
 	do
+		echo "checking $cmd"
 		if ! is_command "$cmd"
 		then
 			log "the full list of required software: [$required]"
@@ -454,13 +467,12 @@ cpu=''
 os=''
 out_dir='/opt'
 pkg_ext='tar.gz'
-
 parse_opts $*
-check_required
 
 echo 'starting AdGuard Home installation script'
 
 configure
+check_required
 
 if ! is_root
 then