make sure getopt tool is present

gencert.sh

@@ -2,7 +2,7 @@
 # Filename: gencert.sh
 # Description: This script generates x509 server certificate (with all IPs in
 #              SAN) signed by a self-signed CA.
-# Version: 1.0 - 2018 July 11
+# Version: 1.1 - 2018 July 15
 # Author: Andrey Arapov <andrey.arapov@nixaid.com>
 # License: GPLv3
 
@@ -123,7 +123,7 @@ set -e
 #  install openssl
 ##
 
-install_openssl() {
+has_openssl() {
   set +e
   type openssl >/dev/null 2>&1
   if [ $? -eq 0 ]; then
@@ -157,6 +157,44 @@ install_openssl() {
   set -e
 }
 
+#  install getopt
+##
+
+has_getopt() {
+  set +e
+  type getopt >/dev/null 2>&1
+  if [ $? -eq 0 ]; then
+    return;
+  fi
+
+  if [ $(id -u) -ne 0 ]; then
+     echo "This script must be run as root in order to install getopt tool."
+     echo "If you cannot run this script as root, then make sure you have the getopt tool."
+     exit 1
+  fi
+
+  if [ -f /etc/debian_version ]; then
+    echo "[${ME}] Installing getopt in Debian/Ubuntu"
+    export DEBIAN_FRONTEND=noninteractive
+    apt-get update
+    apt-get -y install util-linux
+  elif [ -f /etc/alpine-release ]; then
+    echo "[${ME}] Installing getopt in Alpine"
+    apk add --update busybox
+    ln -sv $(type -p busybox) /usr/bin/getopt
+  elif [ -f /etc/centos-release ]; then
+    echo "[${ME}] Installing getopt in CentOS"
+    yum -y install util-linux
+  fi
+
+  type getopt >/dev/null
+  if [ $? -ne 0 ]; then
+    echo "[${ME}] ERROR: Could not install getopt. Exitting."
+    exit 1
+  fi
+  set -e
+}
+
 #  generate openssl config
 ##
 
@@ -212,7 +250,8 @@ gen_server_x509() {
 start() {
   echo "[${ME}] Started in ${PWD} directory."
 
-  install_openssl;
+  has_openssl;
+  has_getopt;
   gen_openssl_config;
   
   if [ ! -f "${CA_KEY}" ]; then