Added check at start to ensure all required applications are installed (0.8)

checkssl

@@ -24,11 +24,12 @@
 # 2015-12-06 Added --renew argument to list domains ready for renew v0.4 - srvrco)
 # 2015-12-19 Added --command argument to perform action to renew certs ( or send email or anything else needed) (v0.5 srvrco)
 # 2016-01-07 Added option to just provide domain name on command line (v0.6 srvrco)
-# 2016-01-30 Ipdated after using shellcheck to maintain a better coding standard (0.7)
+# 2016-01-30 Updated after using shellcheck to maintain a better coding standard (0.7)
+# 2016-01-31 Added check at start to ensure all required applications are installed (0.8)
 # ---------------------------------------------------------------------------
 
 PROGNAME=${0##*/}
-VERSION="0.7"
+VERSION="0.8"
 RENEW_ALERT="30" # set to number of days to be alerted for certificate renewal ( default, can be changed with -expires argument)
 
 clean_up() { # Perform pre-exit housekeeping
@@ -61,7 +62,8 @@ signal_exit() { # Handle trapped signals
 }
 
 usage() {
-  echo -e "Usage: $PROGNAME [-h|--help] [-d|--debug] [-f|--file filename] [-s|--server stype] [-l|--location directory] [-e|--expires days] [-r:--renew] [-c:--command command] [domain]"
+  echo -e "Usage: $PROGNAME [-h|--help] [-d|--debug] [-f|--file filename] [-s|--server stype] [-l|--location directory] 
+                [-e|--expires days] [-r:--renew] [-c:--command command] [domain]"
 }
 
 log() {
@@ -74,31 +76,41 @@ debug() {
   fi
 }
 
+_requires() {
+  result=$(which "$1" 2>/dev/null)
+  debug "checking for required $1 ... $result"
+  if [ -z "$result" ]; then
+    error_exit "This script requires $1 installed"
+  fi
+}
+
 help_message() {
-   cat <<- _EOF_
-   $PROGNAME ver. $VERSION
-   checks ssl certs for a set of domains
-
-   $(usage)
-
-   Options:
-  -h, --help  Display this help message and exit.
-  -d, --debug  outputs debug information
-  -f, --file  filename
-    Where 'filename' is a file containing a list of domain names
-  -s, --server server_type
-    Where 'server_type' is the server type (cpanel, ISPconfig, apache2 ...)
-  -l, --location directory
-    Where 'directory' is where your lets encrypt live directory is
-       (typically /etc/letsencrypt/live/)
-  -e, --expires days
-    Where 'days' is the number of days to alert if cert expires in that time period
-  -r, --renew  this just lists domain names that need to be renewed.   This list could be used by an auto renew script, or to email you.
-  -c, --command run_command
-    Where 'run_command' is a command which will be run ( with domain name passed) for any certs due for renewal
-
-    a domain name can also be specified on the command line
-_EOF_
+  cat <<- _EOF_
+	$PROGNAME ver. $VERSION
+	Checks ssl certs for a set of domains
+
+	$(usage)
+
+	Options:
+	  -h, --help      Display this help message and exit.
+	  -d, --debug     Outputs debug information
+	  -f, --file  filename
+                  Where 'filename' is a file containing a list of domain names
+	  -s, --server server_type
+                  Where 'server_type' is the server type (cpanel, ISPconfig, apache2 ...)
+	  -l, --location directory
+                  Where 'directory' is where your lets encrypt live directory is
+                  (typically /etc/letsencrypt/live/)
+	  -e, --expires days
+                  Where 'days' is the number of days to alert if cert expires in that time period
+	  -r, --renew  this just lists domain names that need to be renewed.   
+                  This list could be used by an auto renew script, or to email you.
+	  -c, --command run_command
+                  Where 'run_command' is a command which will be run (with domain name passed) 
+                  for any certs due for renewal
+
+                  A domain name can also be specified on the command line
+	_EOF_
   return
 }
 
@@ -138,11 +150,20 @@ done
 
 # Main logic
 
+#check if required applications are included
+
+_requires openssl
+_requires mktemp
+_requires grep
+_requires awk
+_requires column
+
 if [[ ! $FILEARG && ! $SERVERARG && ! $LOCATIONARG && ! $DOMAINARG ]]; then
   help_message
   graceful_exit
 fi
 
+
 # create temporary file for the list of domains, and output
 LIST_OF_DOMAINS=$(mktemp)
 DATA_OUT=$(mktemp)