logview

#!/bin/bash
# ------------------------------------------------------------------
# [Paul Borowicz] System Admin Project 3 for MOBI
#          logfile viewer script
# ------------------------------------------------------------------

### UNCOMMENT NEXT 2 LINES FOR DEBUGGING
#set -x
#trap read debug

VERSION=0.1.0
SUBJECT=some-unique-id
#USAGE='This script will display log files
#	it accepts these flags:
#	-h # number of lines to display from top
#	-t # number of lines to display from bottom
#	-k <string> display lines with matching string
#	-v version
#
#	logview <options> <logfile1> <logfile2> ...'

### ---- FUNCTIONS ###

#This checknum function verifies that the variable is a number
function checknum {
test $1 -ge 0 &> /dev/null

if [ $? -gt 1 ]; then
    echo "This flag requires an integer, exiting."
exit
fi
}
#### -------- ###### ----------

USAGE=$(cat <<-END
	This script will display log files
        it accepts these flags:
        -h # number of lines to display from top
        -t # number of lines to display from bottom
        -k <srting> display lines with matching string
        -v version

        logview <options> <logfile1> <logfile2> ...
END
)


# --- Options processing -------------------------------------------

# display help if --help is appended to the command
if [ "$1" = "--help" ] 
	then
		echo "$USAGE"
	exit 1;
fi

#display usage is command has nothing appended
if [ $# == 0 ] ; then
    echo "$USAGE"
    exit 1;
fi

##process flags v, t, k, & h as specified below
## require flags to have options and exclude any flags not specified
while getopts ":v:t:k:h:" optname
  do
    case "$optname" in
	#display version
      "v")
        echo "Version $VERSION"
        exit 0;
        ;;
	# get -t, and put it in frombot
      "t")
	#set t flag arguement to frombot variable
	frombot=$OPTARG
	checknum $frombot
	;;
	# get -k and put it in matchme
      "k")
	#set k flag argument to matchme string
	matchme=$OPTARG
	;;	
	# get -h and put it in fromtop
      "h")
	#set h flag argument to fromtop variable
        fromtop=$OPTARG
	checknum $fromtop
        ;;
	# exclude any unspecified flags
      "?")
        echo "Unknown option $OPTARG"
        exit 0;
        ;;
	# error if no arguments given with flags
      ":")
        echo "No argument value for option $OPTARG"
        exit 0;
        ;;
	# exclude any longer uspecified flags
      *)
        echo "Unknown error while processing options"
        exit 0;
        ;;
    esac
  done

shift "$(($OPTIND - 1))"


# --- Locks -------------------------------------------------------
LOCK_FILE=/tmp/$SUBJECT.lock
if [ -f "$LOCK_FILE" ]; then
   echo "Script is already running"
   exit
fi

trap "rm -f $LOCK_FILE" EXIT
touch $LOCK_FILE

# --- Body --------------------------------------------------------
#  SCRIPT LOGIC GOES HERE

#make working directory /var/log, exit if it cannot
cd /var/log ||exit

#Tell user what's going on
echo "Processing the following log files: $@"
echo "$#" ' file(s)'
while [ "$1" ]
	do
	 echo "---------"
		if [ -f $1 ]
		then
			#check if fromtop (h) was provided
			if [ -n "$fromtop" ]; then
				#display lines from top of file as specified
				echo "Top $fromtop lines for $1:"
				head -$fromtop $1
			fi

			#check if matchme (k) was provided
			if [ -n "$matchme" ]; then
				#grep file for anything matching matchme string
				echo "displaying lines with $matchme:"
				grep $matchme $1
			fi
			#check if frombot (t) was provided, output specified number of lines form bottom
                        if [ -n "$frombot" ]; then
                       		# display the bottom lines of file as specifed in frombot variable
				echo "Bottom $frombot lines of $1:"
                        	tail -$frombot $1
			else 
				# check if other flags are present, skip default action if they are
				# if no other flags are present and frombottom is unset
				# perform these default actions
				if [ -z "$matchme" ] && [ -z "$fromtop" ]
				then
				#set frombot to 3, the default
				frombot=3
				echo "Bottom $frombot lines of $1:"
				tail -$frombot $1
				fi
			fi
		else
			echo "$1 not found."
		fi
	 shift
	done
# -----------------------------------------------------------------