answer to a friend's friend's question

sp2011.sh

#!/bin/bash

error () {
# USAGE: error <message> <is_fatal>
    echo -n "!!ERROR!! " 1>&2
    echo "$1" 1>&2
    if (( "$2" )); then
        exit 1
    fi
}

write_menu () {
    echo "1. Current date"
    echo "2. Show content of file"
    echo "3. Compile a C++ program"
    echo "0. Exit"
}

clear

while true; do
    write_menu
    read -p "Your choice? (0-3) "
    echo # add a blank line
    case $REPLY in
        1)
            date +%d-%b-%Y | tr [:lower:] [:upper:]
            ;;
        2)
            read -p "Input filename: " filename
            if [ -e "$filename" ]; then
                echo "$filename exists"
                if [ -r "$filename" ]; then
                    echo "<Begin content of $filename>"
                    cat "$filename"
                    echo "<End content of $filename>"
                else
                    error "$filename is not readable" 0
                fi
            else
                error "$filename does not exist" 0
            fi
            ;;
        3)
            read -p "Input filename: " filename
# redirect errors to where? I redirect them to /dev/null here
            g++ "$filename" 2>/dev/null
            if [ $? -eq 0 ]; then
                echo "Successfully built the program"
                mv -i a.out "${filename%\.*}"
            else
                error "Something went wrong on the g++ side" 0
            fi
            ;;
        0)
            echo "Quitting..."
            exit
            ;;
        *)
            error "Invalid choice" 0
            ;;
    esac
    echo # add a blank line
done