Реализовать загрузочный скрипт Linux Bash systemd

#!/bin/bash
declare -a arr
echo -n "Size of Matrix NxN:"
read rows;
cols=$rows
 
maxmain=0
maxsecondary=0
 
 
 
#input elem matrix
row=0
while [ $row -lt $rows ]
do
    col=0
    while [ $col -lt $cols ]
    do
        echo -n "[$row][$col]:"
        read val
        index=$((row*rows+col))
        arr[$index]=$val
        let col+=1
    done
    let row+=1
done
 
echo "Initial Matrix:"
 
#vivod
row=0
while [ $row -lt $rows ]
do
    col=0
    while [ $col -lt $cols ]
    do
        index=$((row*rows+col))
        echo -n "${arr[index]} "
        let col+=1
    done
    let row+=1
    echo
done
 
 
#min
row=0
while [ $row -lt $rows ]
do
    col=0
    while [ $col -lt $cols ]
    do
        index=$((row*rows+col))
        
        if [ $row -eq $col ]
        then
            if [ ${arr[index]} -gt $maxmain ]
            then
                maxmain=${arr[index]}
            fi
        fi
        let col+=1
    done
    let row+=1
done
 
 
row=0
while [ $row -lt $rows ]
do
    col=0
    while [ $col -lt $cols ]
    do
        index=$((row*rows+col))
        
        if [ $row -eq $((rows-1-col)) ]
        then
            if [ ${arr[index]} -gt $maxsecondary ]
            then
                maxsecondary=${arr[index]}
            fi
        fi
        let col+=1
    done
    let row+=1
done
 
 
echo "Max main:$maxmain"
echo "Max maxsecondary:$maxsecondary"
 
#swap  
for (( i=0; i < $rows; i++ ))
do
    index=$((i*rows+i))
    swap=${arr[index]}
    if [ ${arr[index]} -ne $maxmain ]
    then
        arr[index]=${arr[(i+1)*$rows - (i+1)]}
    fi
    if [ ${arr[(i+1)*$rows - (i+1)]} -ne $maxsecondary ]
    then
        arr[(i+1)*$rows - (i+1)]=$swap
    fi
done
#vivod
row=0
while [ $row -lt $rows ]
do
    col=0
    while [ $col -lt $cols ]
    do
        index=$((row*rows+col))
        echo -n "${arr[index]} "
        let col+=1
    done
    let row+=1
    echo
done

[Unit] 
Description=My_Script 
After=runlevel4.target 
[Service] 
Type=simple 
ExecStart=/home/student/lab2/Lab2
WorkingDirectory=/etc/systemd/system 
[Install] 
WantedBy=runlevel4.target