Add check requirement

... and some shell fixes

check_ssl

@@ -16,10 +16,11 @@
 #
 # 2017-03-03  v1.0  ah,ds
 # 2020-03-05  v1.1  <axel.hahn@iml.unibe.ch> switch to ph.* helper functions
+# 2023-02-13  v1.2  <axel.hahn@unibe.ch>     some shell fixes
 # ======================================================================
 
 
-. `dirname $0`/inc_pluginfunctions
+. $(dirname $0)/inc_pluginfunctions
 
 sDomain=
 iPort=443
@@ -41,7 +42,7 @@ function showHelp(){
   echo
   echo ----- SSL Check v1.0
   echo
-  echo "SYNTAX: `basename $0` [domain] [[port]]"
+  echo "SYNTAX: $(basename $0) [domain] [[port]]"
   echo "   domain - domain to verify the ssl vertificate from (required)"
   echo "   port   - port number to connect (default: 443)"
   echo
@@ -81,7 +82,7 @@ function showHelp(){
     ph.exit
   fi
 
-  echo | openssl s_client -connect ${sDomain}:${iPort} 2>/dev/null | openssl x509 -noout -subject | fgrep ${sDomain} >/dev/null
+  echo | openssl s_client -connect ${sDomain}:${iPort} 2>/dev/null | openssl x509 -noout -subject | grep -F ${sDomain} >/dev/null
   if [ $? -ne 0 ]; then
     ph.setStatus "unknown"
     echo SORRY, openssl was unable to fetch the right certificate - this happens on multiple ssl webs - it finds
@@ -91,13 +92,13 @@ function showHelp(){
 
 # --- unix timestamps valid from .. to
 
-  dateFrom=`echo | openssl s_client -connect ${sDomain}:${iPort} 2>/dev/null | openssl x509 -noout -startdate | cut -f 2 -d "="`
-  dateTo=`echo   | openssl s_client -connect ${sDomain}:${iPort} 2>/dev/null | openssl x509 -noout -enddate   | cut -f 2 -d "="`
+  dateFrom=$(echo | openssl s_client -connect ${sDomain}:${iPort} 2>/dev/null | openssl x509 -noout -startdate | cut -f 2 -d "=")
+  dateTo=$(echo   | openssl s_client -connect ${sDomain}:${iPort} 2>/dev/null | openssl x509 -noout -enddate   | cut -f 2 -d "=")
 
-  tsFrom=`date -d "${dateFrom}" +%s`
-  tsTo=`date -d "${dateTo}" +%s`
+  tsFrom=$(date -d "${dateFrom}" +%s)
+  tsTo=$(date -d "${dateTo}" +%s)
 
-  tsNow=`date +%s`
+  tsNow=$(date +%s)
   typeset -i iDaysLeft=($tsTo-$tsNow)/60/60/24