math task generator

gistfile1.txt

#!/bin/bash 




answer_pattern="<ans>"
answer_text="____"
columns_per_row=3

export answer_pattern answer_text columns_per_row tasks

dbg() {

        echo "$*" >&2
}

replace_shell() {

        local row="$1" varname varvalue cmd res 

        if [[ "$row" =~ \{[^{}]+=[^{}]+\} ]] ; then
                # replace a line with a variable definition if { ... = ... } is found

                [[ $row =~ \{([^=]+)=([^}]+)\} ]] 
                varname="${BASH_REMATCH[1]}"

                # evaluate var definition twice, so a command to generate the value will be executed
                eval varvalue="${BASH_REMATCH[2]}"

                # replace $varname and remove variable definition
                sed -r <<<"$row"                        \
                        -e "s/\\\$$varname/$varvalue/g" \
                        -e "s/\{[^{}]+\}//g" 
        else
                # else replace shell code in template { ... } as long as there are still unresolved { ... } blocks
                while [[ $row =~ \{([^{}]+)\} ]] ;do 
                        [[ $row =~ \{([^{}]+)\} ]] 
                        cmd="${BASH_REMATCH[1]}"
                        res="$($cmd)"
                        row="$(sed -r -e "s/\{[^{}]+\}/$res/" <<<"$row")"
                done
                echo "$row"
        fi

}

task_output() {

        local idx task lines 

        # get total number of rows to be printed
        lines=$(( ($taskcount + $columns_per_row - 1) / $columns_per_row ))

        # generate randomized index for output
        idx=($(shuf -e $( seq 1 ${#tasks[@]} )))

        for((line=1,i=0;line<=lines;line++));do
                for((col=1;col<=columns_per_row;col++));do
                        ((i++))
                        task="${tasks[${idx[$i]}]}"
                        # change output field size here if necessary
                        [ -n "${idx[$i]}" ] && \
                        printf "%2d) %-20s" "$(( $line + (($col - 1) * $lines) ))" "$task"
                done

                echo -e "\n"
        done

}

main() {
        local line content result count tasks template=$1

        # read the template and render the requested number of the single tasks
        while read line ; do
                [[ $line =~ ^# ]] && continue
                content="${line%%|*}"
                count="${line##*|}"
                for((i=1;i<=count;i++)) ; do
                        result="$(replace_shell "$content")"
                        tasks[++taskcount]="${result//$answer_pattern/$answer_text}"
                done
        done <$template

        task_output 

}

# PROGRAM STARTS HERE

main ${1:-magnus.tmpl}

gistfile2.txt

#
#   example template file: magnus.tmpl
#
#    question                   | times
#-------------------------------+-----------------
{rnd1=$(shuf -i 1-9 -n 1)}$rnd1 + $rnd1 = <ans>|7
{shuf -i 10-20 -n 1} - 1 = <ans>|3
{shuf -i 10-20 -n 1} + 1 = <ans>|5
{shuf -i 1-9 -n 1} + <ans> = 10|5
{shuf -i 1-99 -n 1} - 10 = <ans>|5
10 - <ans> = {shuf -i 1-9 -n 1}|5
10 x {shuf -i 1-10 -n 1} = <ans>|5
{shuf -i 11-99 -n 1} + {shuf -n 1 -e 10 20 30 40 50 60 70 80 90} = <ans>|5
Is {shuf -i 1-9 -n 1} O / E  <ans>|5