#!/bin/bash
print_info() {
:
}
configure_func_1() {
:
}
configure_func_2() {
:
}
#...
configure_func_k() {
:
}
print_oplist() {
cat <<oplist
1. Print network info
2. Configure_1
3. Configure_2
...
k. Configure_k
0. Exit
oplist
}
 
#Main
echo "Choose operation:"
print_oplist
read op
while [ "$op" != "0" ]; do
case "$op" in
    1) print_info ;;
    2) configure_func_1 ;;
    3) configure_func_2 ;;
#...
    k) configure_func_k ;;
    0) : ;;
    *) echo "Illegal operation" ;;
esac
if [ "$op" != "0" ]; then
    print_oplist
fi
read op
done

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MA==

Standard input is empty