#!/bin/sh
#############################################################
# Course: Unix System Administration and Programming        #
# Assignment: assignment 2                                  #
# Author: Vicky Perdana                                     #
#############################################################
# Unset PATH variable to ensure subsequent commands
# do not rely on PATH environment variable
PATH=

# DEFPATH is a location of directory path for Configuration file
# TMPPATH is a location of directory path for temporary file
DEFPATH="/home/v/vsuryape/courses/cosc1133/assignments/part2"
TMPPATH="/tmp"

# Setting full path command variables
# These commands are specific to PATH environment variable
# Change/add below if your PATH is different
DEF="/usr/bin"
DEF1="/usr/ucb"
DEF2="/usr/local/bin"
GREP="$DEF/grep"
AWK="$DEF2/awk"
TEST="$DEF/test"
SED="$DEF/sed"
PS="$DEF/ps"
ECHO="$DEF/echo"
FIND="$DEF/find"
DATE="$DEF/date"
EXPR="$DEF/expr"
WC="$DEF/wc"
TOUCH="$DEF/touch"
MAILX="$DEF/mailx"
CAT="$DEF/cat"
DIRNAME="$DEF/dirname"
PWD="$DEF/pwd"
RM="$DEF/rm"

# Script Configuration file
CONF=$DEFPATH/script-conf
CONFTEMP=$TMPPATH/script-conf.temp.$$

# Temp file for stderr and stdout
ERRTEMP=$TMPPATH/${0}.1.$$

# Admin email Address
ADMIN="vsuryape"

# Function checkProcess() performs the fundamental part
# of this script. In overall, this script will check
# whether all commands specified in Configuration file are
# found and will try to start it if it's not available
# However, if problem persists, useful messages will
# be emailed to Admin
checkProcess()
{
   COUNTER=1

   LINENUM=`$WC -l $CONF | $AWK '{print $1}'` # get num of lines
   # Process the Config file
   while $TEST $COUNTER -le $LINENUM ; do

      LINE=`$SED -n "$COUNTER"p $CONF | $AWK '{sub(/^#\t..*/, ""); print}'`
      COMMAND=`$SED -n "$COUNTER"p $CONF | $AWK -F'[\t]' '{print $1}'`
      STARTCOMMAND=`$SED -n "$COUNTER"p $CONF | $AWK -F'[\t]' '{print $2}'`
      FPCOMMAND="`$ECHO $LINE | $AWK '{print $2}'`"

      # Checkpoint 1: Check for blank line and empty string
      # for field 1 and 2
      CHECK1=0
      if $TEST "$LINE" = "" -o "$COMMAND" = "" -o "$STARTCOMMAND" = ""
      then
         $ECHO "Could not process line number $COUNTER"
         COUNTER=`$EXPR $COUNTER + 1`
         CHECK1=1
         continue
      fi

      CONFCOMMAND=`$SED -n "$COUNTER"p $CONF | $AWK -F'[\t]' '{print $3}'`

      # Checkpoint 2: Check whether command is currently running
      # and attempt to run it if it isn't, if problem persists
      # set CHECK2 flag to false (1)
      CHECK2=0
      # Search for command in the list of processes
      $PS -ef | $GREP -v grep | $GREP $COMMAND > /dev/null 2>&1
      FOUND=$?
      if $TEST $FOUND -ne 0 ; then
         $TOUCH $ERRTEMP
         if $TEST ! -r $FPCOMMAND -a ! -s $FPCOMMAND ; then
            CHECK2=2
         else
            $STARTCOMMAND >$ERRTEMP 2>&1
            STATUS=$?
            if $TEST $STATUS -ne 0 ; then
               CHECK2=1
            fi
         fi
      fi

      # Checkpoint 3: Check for the existence of config file
      # if ONLY daemon config file was supplied
      # Store stderr message from find command into temp file
      # if any
      CHECK3=0
      if $TEST "$CONFCOMMAND" != "" ; then
         $FIND $CONFCOMMAND >>$ERRTEMP 2>&1
         if $TEST ! -r $CONFCOMMAND ; then
            CHECK3=1
         fi
      fi

      # Now, perform main operation, first create unique temp file
      # This is performed only if CHECK3=1
      if $TEST $CHECK2 -ne 0 ; then
         $TOUCH $CONFTEMP
         $ECHO "Configuration script file: $CONF" > $CONFTEMP
         $ECHO "\nProcess '$COMMAND' not listed in ps -ef" >> $CONFTEMP
         $ECHO "\nCould not start '$STARTCOMMAND'"  >> $CONFTEMP
         if $TEST $CHECK3 -eq 1 ; then
            $ECHO "\nDaemon configuration file could not be found and is not readable"  >> $CONFTEMP
         fi
         if $TEST -s "$ERRTEMP" ; then
            $ECHO "\nOutput from STDOUT and Error Messages from STDERR: "  >> $CONFTEMP
            $CAT $ERRTEMP >> $CONFTEMP # append STDERR & STDOUT info into Email
            $RM $ERRTEMP > /dev/null 2>&1
         fi
      # Send email to admin using mailx
      $MAILX -s "`$DATE` 3065944 Daemon Monitor" $ADMIN < $CONFTEMP
      fi

      COUNTER=`$EXPR $COUNTER + 1`
   done
}

# Main Method
# Check whether configuration file exist and not empty
# for convenience, one can provide one argument which is the filename
# of the config file
if $TEST "$#" -gt 1 ; then
   $ECHO "Only one argument is allowed to be passed\nAttempt to exit"
   exit 1
elif $TEST "$1" != "" ; then
   if $TEST -s "$1" ; then
      if $TEST "`$DIRNAME $1`" = "." ; then
         CONF="`$PWD`/$1"
      else
         CONF="$1"
      fi
   else
      $ECHO "Configuration file is not existed and/or empty\nAttempt to exit"
      exit 1
   fi
elif $TEST ! -s $CONF ; then
   $ECHO "Configuration file is not existed and/or empty\nAttempt to exit"
   exit 1
fi
checkProcess