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Bug: Alert title without single quotes.

    1: #!/bin/bash
    2: 
    3: # canardien 0.0.4
    4: # (c) 2005-2019 under GPL by Adrian Zaugg
    5: 
    6: 
    7: # canardien [<host> [<host> ...]]
    8: 
    9: # canardiens pings a machine, originally ente.limmat.ch thus its name, 
   10: # to determine wether she is gone diving.
   11: 
   12: 
   13: ## Settings
   14: #
   15: 
   16: # Hosts to ping. use a space separated list for multiple targets. All
   17: # hosts of the list are checked and their results reported individually.
   18: # Hosts given on the command line overwrite this setting.
   19: HOSTS=""
   20: 
   21: # eMail Alerts
   22: # Send alert email messages to the following address(es). Leave empty
   23: # for no alert. For multiple destinations use a comma separated list.
   24: ALERT_TO="root"
   25: 
   26: # Subject of alert email
   27: ALERT_SUBJECT='"Attention: no answer from $HOST anymore!"'
   28: 
   29: # Text of Message (Put variables in 'single quotes' to protect them. They
   30: # should get expanded at the time the message is sent!)
   31: ALERT_TEXT='"\n[$TIME_STAMP]\n\nALERT!!\n\n\t$HOST is down!\n\nYou should probably do something, please.\n\nKind regards, $PINGHOST."'
   32: 
   33: # Path to fping
   34: PING=""
   35: 
   36: # Answer of fping to reachable hosts
   37: ALIVE_ANSWER="is alive"
   38: 
   39: # Max number of pakets to send before giving up. Time increases exponentially,
   40: # use a number < 7.
   41: RETRIES=4
   42: 
   43: # Temporary file path
   44: TMPDIR="/tmp"
   45: 
   46: # This hosts name
   47: PINGHOST="$(uname -n)"
   48: 
   49: # Set to an empty string to avoid debug output,
   50: # to "low" for a few, output and to anything else
   51: # for verbose output
   52: DEBUG=verbose
   53: 
   54: # For silent (non-error) operation set to anything,
   55: # comment out to enable text output
   56: #SILENT=shshsh
   57: 
   58: 
   59: # -----------functions-----------
   60: 
   61: # Initialize.
   62: function init() {
   63: 
   64: 	# check fping existence
   65: 	if [ -z "$PING" ]; then
   66: 		PING="$(which fping)"
   67: 	fi
   68: 	if [ ${#PING} -eq 0 ]; then
   69: 		echo "Error: fping external program not found or not set. Exitting." >&2
   70: 		exit 1
   71: 	fi
   72: 	if [ ! -x "$PING" ]; then
   73: 		echo "Error: Can't execute the program set to use as fping. Please enter the correct path to \"fping\"." >&2
   74: 		exit 1
   75: 	fi
   76: 
   77: 	# get hostset
   78: 	if [ -n "$*" ]; then
   79: 		HOSTS="$*"
   80: 	fi
   81: 	if [ -z "$HOSTS" ]; then
   82: 		echo "Error: No host to ping." >&2
   83: 		exit 0
   84: 	fi
   85: }
   86: 
   87: 
   88: # If a host responds to pings, it is considered up.
   89: function checkconnection() {
   90: 	
   91: 	while read -r HOST; do
   92: 		unset UP
   93: 
   94: 		# ping host
   95: 		PING_ANSWER="$($PING -R -B 2 -r $RETRIES -p 50 "$HOST" 2>&1)"
   96: 		PING_ERRNUM=$?
   97: 		if [ $PING_ERRNUM -gt 2 ]; then
   98: 			echo "Error: Got error $PING_ERRNUM from fping $(head -1 "$PING_ANSWER"). Disregarding $HOST." >&2
   99: 			continue;
  100: 		fi
  101: 
  102: 		# parse answer
  103: 		if [ $(echo "$PING_ANSWER" | grep -c "$ALIVE_ANSWER") -gt 0 ]; then
  104: 			UP=true
  105: 		fi
  106: 		TIME_STAMP="$(date +"%a %e.%m.%y %H:%M:%S")"
  107: 		if [ -n "$UP" ]; then
  108: 			if [ ! "$DEBUG" = "low" ] && [ -n "$DEBUG"  ]; then
  109: 				shout "The connection to $HOST is up."
  110: 			fi
  111: 		else 
  112: 			if [ -n "$DEBUG" ]; then
  113: 				shout "The connection to $HOST is down."
  114: 			fi
  115: 		fi
  116: 		
  117: 		# remember a hosts state
  118: 		rememberstate
  119: 		
  120: 	done <<< "$(echo "$HOSTS" | tr ' ' '\n')"
  121: }
  122: 
  123: 
  124: # Rember recent state of host, trigger alert
  125: function rememberstate() {
  126: 	# Put a simple time stamp in a tmp file, when host is detected as down for the first time
  127: 	if [ -z "$UP" ]; then
  128: 		if [ ! -e "$TMPDIR/.canardien-$PINGHOST-$HOST" ]; then 
  129: 				# set time stamp
  130: 				echo -ne "$TIME_STAMP" > "$TMPDIR/.canardien-$PINGHOST-$HOST"
  131: 				# send alert
  132: 				sendalert
  133: 			elif [ -n "$DEBUG" ]; then
  134: 				shout "Down since `cat $TMPDIR/.canardien-$PINGHOST-$HOST`."
  135: 			fi
  136: 	else 
  137: 	  # Host is up
  138: 		if [ -e "$TMPDIR/.canardien-$PINGHOST-$HOST" ]; then
  139: 			if [ -n "$DEBUG" ]; then
  140: 				shout "$HOST is up again."
  141: 			fi
  142: 		  # send alert
  143: 			 ALERT_SUBJECT='"The host $HOST answers again!"'
  144: 			 ALERT_TEXT='"[$(date +"%a %e.%m.%y %H:%M:%S")]\n\n\n$HOST is up again.\n--------------------------------------\n(downtime began $(cat "$TMPDIR/.canardien-$PINGHOST-$HOST"))\n\n\n		Kind regards, $PINGHOST."'
  145: 			 sendalert
  146: 			# delete tmp file
  147: 			rm "$TMPDIR/.canardien-$PINGHOST-$HOST"
  148: 		else 
  149: 			# still running
  150: 			if [ ! "$DEBUG" = "low" ] && [ -n "$DEBUG"  ]; then
  151: 				shout "$HOST is up."
  152: 			fi
  153: 		fi
  154: 	fi
  155: }
  156: 
  157: 
  158: # Send an email alert
  159: function sendalert() {
  160: 	# send mail
  161: 	if [ ! -z "$ALERT_TO" ]; then
  162: 			eval alert_subject=\$$ALERT_SUBJECT
  163: 			eval MSG=\$$ALERT_TEXT
  164: 			echo -e -n "$MSG" | mail -s "$alert_subject" "$ALERT_TO"
  165: 			if [ -n "$DEBUG" ]; then
  166: 				shout "Alert sent to $ALERT_TO."
  167: 			fi
  168: 	fi
  169: }
  170: 
  171: 
  172: # To avoid any output in case of a silent operation,
  173: # shout instead of echo.
  174: function shout() {
  175: 	if [ -z "$SILENT" ]; then
  176: 		echo -e "$1"
  177: 	fi
  178: }
  179: 
  180: 
  181: # -----------main-----------
  182: 
  183: init "$*"
  184: checkconnection
  185: exit 0