#! /bin/sh
# Usage : ./crontabintf

set -f
choice=0
while [ 0 ]
do 
    echo "1.Display crontab jobs."
    echo "2.Insert a job."
    echo "3.Remove a job."
    echo "4.Exit."
    echo -n "Select>"
    read choice

    case $choice in
      1)    line=1
        crontab -l > $HOME/.jobs
        res="`wc -l $HOME/.jobs`"
        set - $res;lines=$1;
        while [ $line -le $lines ] 
        do
            res="`head -$line $HOME/.jobs | tail -1`"
            set - $res;disp=" ";
            for arg
            do
                if [ "$arg" = '*' ]
                then 
                     disp="$disp Any"
                else
                    disp="$disp $arg"
                fi
            done 
            set - $disp
            echo "JOB $line-->"
            echo "minute: $1";shift;
            echo "Hour: $1";shift;
            echo "Date: $1/$2";shift;shift;
            echo "Day of week: $1";shift;
            echo "Command:$*"
            line=`expr $line + 1`
        done;;
       2)    crontab -l >$HOME/.newjobs
        selection=0
        minutes="any"
        hours="any"
        monthday="any"
        month="any"
        weekday="any"
              while [ $selection -ne 7 ]
        do
            echo "1.Set the command(-obligatory):"
            echo "Set periodicity of command."
            echo "2.Set minutes:0-59"
            echo "3.Set hours:0-23"
            echo "4.Set day of month:1-31"
            echo "5.Set month:1-12"
            echo "6.Set day of week:Mon-Sun"
            echo "7.Ready."
            echo -n "Enter>"
            read selection 
            case $selection in
            1)echo -n "Enter>"
                read command;;
2)    echo -n "If more than one choice,seperate by comma..Enter>"
                read minutes;;  
3)    echo -n "If more than one choice,seperate by comma..Enter>"
                read hours;;
4)    echo -n "If more than one choice,seperate by comma..Enter>"
                     read monthday;;
5)    echo -n "If more than one choice,seperate by comma..Enter>"
                read month;;
6)    echo -n "If more than one choice,seperate by comma..Enter>"
                read weekday;;
            7)     break;;
            *)        continue;;
            esac
        done
        periodicity=" "
        for inst in $minutes $hours $monthday $month $weekday
        do
            if [ "$inst" = "any" ] 
            then
                periodicity="$periodicity *"
            else
                periodicity="$periodicity $inst"
            fi
        done
        echo "$periodicity $command">>$HOME/.newjobs
            crontab $HOME/.newjobs;;
      3)    crontab -l >$HOME/.jobs
        echo "Job to remove"
            echo -n "Enter Job's number as listed above>"
            read jobnmb
                res="`wc -l $HOME/.jobs`"
            set - $res;
        rest=`expr $1 - $jobnmb`
            jobnmb=`expr $jobnmb - 1`
            head -$jobnmb $HOME/.jobs | cat >$HOME/.njobs
        tail -$rest $HOME/.jobs | cat >>$HOME/.njobs
        crontab $HOME/.njobs;;
        4)    rm $HOME/.jobs $HOME/.newjobs
         exit;;
      *)  continue;;
    esac
done