CAL

#!/bin/bash
#Author: John Bohne
#Date: 12/3/2012
#Program: CAL
#Program Description: Accepts more than one month in the command line ie CAL feb mar jun or CAL jan - oct and displays the months.
#					  Currently only works for the year 2013.
number_of_args=$#
if [ $# -eq 0 ] #no arguments
then
   set `date`
    m=$2
	case $m in
        jan*|Jan*) m=1 ;; #if month is begins with jan or Jan, set it to month 1
        feb*|Feb*) m=2 ;;
        mar*|Mar*) m=3 ;;
        apr*|Apr*) m=4 ;;
        may*|May*) m=5 ;;
        jun*|Jun*) m=6 ;;
        jul*|Jul*) m=7 ;;
        aug*|Aug*) m=8 ;;
        sep*|Sep*) m=9 ;;
        oct*|Oct*) m=10 ;;
        nov*|Nov*) m=11 ;;
        dec*|Dec*) m=12 ;;
        [1-9]|10|11|12) ;; #if month is 1-9, 10, 11, or 12, do nothing
        *) y=$m, m="";; #if there is no month given, set year to $m and m to empty string
	esac
	cal $m 2013 #use 2013
elif [ $# -eq 1 ] || [ $# -eq 2 ] #only one or two months as arguments
then
    for n in $*
	do
     m=$n
    case $m in
        jan*|Jan*) m=1 ;; #if month is begins with jan or Jan, set it to month 1
        feb*|Feb*) m=2 ;;
        mar*|Mar*) m=3 ;;
        apr*|Apr*) m=4 ;;
        may*|May*) m=5 ;;
        jun*|Jun*) m=6 ;;
        jul*|Jul*) m=7 ;;
        aug*|Aug*) m=8 ;;
        sep*|Sep*) m=9 ;;
        oct*|Oct*) m=10 ;;
        nov*|Nov*) m=11 ;;
        dec*|Dec*) m=12 ;;
        [1-9]|10|11|12) ;; #if month is 1-9, 10, 11, or 12, do nothing
        *) y=$m, m="";; #if there is no month given, set year to $m and m to empty string
     esac
	 cal $m 2013 #call cal and use the month from the argument
	done
elif [ $number_of_args -eq 3 -a $2 = "-" ] #3 arguments only, month - month format
then
         beginMonth=$1
         endMonth=$3
         case $beginMonth in
                jan*|Jan*) beginMonth=1 ;; #if month is begins with jan or Jan, set it to month 1
        feb*|Feb*) beginMonth=2 ;;
        mar*|Mar*) beginMonth=3 ;;
        apr*|Apr*) beginMonth=4 ;;
       may*|May*) beginMonth=5 ;;
        jun*|Jun*) beginMonth=6 ;;
        jul*|Jul*) beginMonth=7 ;;
        aug*|Aug*) beginMonth=8 ;;
        sep*|Sep*) beginMonth=9 ;;
        oct*|Oct*) beginMonth=10 ;;
                nov*|Nov*) beginMonth=11 ;;
                dec*|Dec*) beginMonth=12 ;;
                [1-9]|10|11|12) ;; #if month is 1-9, 10, 11, or 12, do nothing
                *) y=$beginMonth, beginMonth="";; #if there is no month given, set year to $m and m to empty string
                esac
        case $endMonth in
        jan*|Jan*) endMonth=1 ;; #if month is begins with jan or Jan, set it to month 1
        feb*|Feb*) endMonth=2 ;;
        mar*|Mar*) endMonth=3 ;;
        apr*|Apr*) endMonth=4 ;;
        may*|May*) endMonth=5 ;;
        jun*|Jun*) endMonth=6 ;;
        jul*|Jul*) endMonth=7 ;;
        aug*|Aug*) endMonth=8 ;;
        sep*|Sep*) endMonth=9 ;;
        oct*|Oct*) endMonth=10 ;;
                nov*|Nov*) endMonth=11 ;;
                dec*|Dec*) endMonth=12 ;;
                [1-9]|10|11|12) ;; #if month is 1-9, 10, 11, or 12, do nothing
                *) y=$endMonth, endMonth="";; #if there is no month given, set year to $m and m to empty string
                esac
monthResult=`expr $endMonth - $beginMonth`
                while [ `expr $monthResult + 1`  -gt 0 ] #continue loop until it goes through all of the months
                do
                        cal $beginMonth 2013 #call cal and use the month from range
                        beginMonth=`expr $beginMonth + 1`
                        monthResult=`expr $monthResult - 1` #decrease monthResult
                done
elif [ $number_of_args -ge 3 -a $2 != "-" ] # 3 or more months, NOT month - month format
then
        for j in $*
        do
         m=$j
        case $m in
        jan*|Jan*) m=1 ;; #if month is begins with jan or Jan, set it to month 1
        feb*|Feb*) m=2 ;;
        mar*|Mar*) m=3 ;;
        apr*|Apr*) m=4 ;;
        may*|May*) m=5 ;;
        jun*|Jun*) m=6 ;;
        jul*|Jul*) m=7 ;;
        aug*|Aug*) m=8 ;;
        sep*|Sep*) m=9 ;;
        oct*|Oct*) m=10 ;;
        nov*|Nov*) m=11 ;;
        dec*|Dec*) m=12 ;;
        [1-9]|10|11|12) ;; #if month is 1-9, 10, 11, or 12, do nothing
        *) y=$m, m="";; #if there is no month given, set year to $m and m to empty string
        esac
                cal $m 2013 #call cal and use the month from the argument
        done
else
		echo "Can only accept months for the year 2013 in the format of Jan or January, Feb or February etc."
fi