GETOPTS command does not work in my shell script - shell

Question

Can anybody help me please?
i wrote a script and in my script i used GETOPTS to make options but it does not work
it had some error and i check it in shellcheck.net and fixed them but it's not working
#!/bin/bash
while getopts 'n:c2rFt' option; do
case "$option" in
n) export Field="$OPTARG"
;;
c) #Question 1
cat "$1" | awk '{print $1}' | sort | uniq -c | sort -nrk 1,1 > file1
awk 'NR=="$Field" {print}' file1
;;
2) #Question 2
cat "$1" | awk '{ if($9 == 200) print $1,$9 }' | sort | uniq -c | sort -nrk 1,1 > file1
awk 'NR=="$Field" {print}' file1
;;
r) #Question 3
cat "$1" | awk '{print $1,$9}' | sort | uniq -c | sort -nrk 1,1 > file1
awk 'NR=="$Field" {print}' file1
;;
F) #Question 4
cat "$1" | awk '{if($9 >= 400 && $9 <= 451)} {print $1,$9}' | sort | uniq -c | sort -nrk 1,1 > file1
awk 'NR=="$Field" {print}' file1
;;
t) #Question 5
cat "$1" | awk '{print $1,$10}' | sort | uniq -c | sort -nrk 3,3 > file1
awk 'NR=="$Field" {print}' file1
;;
?)
echo "You used wrong option"
echo "USAGE: log_sum.sh [-n N] (-c|-2|-r|-F|-t|-f) <filename>"
echo " -n: Limit the number of results to N"
echo " -c: shows th IP address makes the most number of connection attempts"
echo " -2: shows th most number of seccessful attempts "
echo " -r: shows th most common result codes and their IP addresses"
echo " -F: shows the most common result codes that indicate failure"
echo " -t: shows the IP addresses that get the most bytes sent to them"
exit 1
;;
esac
done

Answer 1

You have your "business logic" in the wrong place: your code assumes that the user will provide the -n option first. That's not required by getopts. You have to write this kind of program with 3 stages: option parsing, validation and actions:
#!/bin/bash
usage() {
local program=$(basename "$0")
cat <<END_USAGE >&2
USAGE: $program -n N (-c|-2|-r|-F|-t|-f) <filename>
-n: Limit the number of results to N
-c: shows th IP address makes the most number of connection attempts
-2: shows th most number of seccessful attempts
-r: shows th most common result codes and their IP addresses
-F: shows the most common result codes that indicate failure
-t: shows the IP addresses that get the most bytes sent to them
END_USAGE
}
# Option parsing
while getopts ':n:c2rFt' option; do
case "$option" in
n) num_results=$OPTARG ;;
c) show_connections=yes ;;
2) show_successful=yes ;;
r) show_common_results=yes ;;
F) show_common_failures=yes ;;
t) show_most_bytes=yes ;;
?) echo "Error: unknown option $OPTARG"; usage; exit 1 ;;
esac
done
shift $((OPTIND - 1))
filename=$1
# Validation
if [[ -z $num_results ]]; then
echo "Error: you must provide the -n option" >&2
usage >&2
exit 1
fi
if [[ -z $filename ]]; then
echo "Error: you must provide a filename" >&2
usage >&2
exit 1
fi
# Actions
# helper function to encapsulate repeated code
top_results() { sort | uniq -c | sort -nrk 1,1 | sed "${num_results}q"; }
if [[ $show_connections == yes ]]; then
awk '{print $1}' "$filename" | top_results
fi
if [[ $show_successful == yes ]]; then
awk '$9 == 200 {print $1,$9}' "$filename" | top_results
fi
if [[ $show_common_results == yes ]]; then
awk '{print $1,$9}' "$filename" | top_results
fi
if [[ $show_common_failures == yes ]]; then
awk '$9 >= 400 && $9 <= 451 {print $1,$9}' "$filename" | top_results
fi
if [[ $show_most_bytes == yes ]]; then
awk '{print $1,$10}' "$filename" | top_results
fi