C++ Compiling | Running script for competitive programming

run.sh

# compile
clear
if [ -z "$1" ]
then
    echo "$0 Usage:"
    echo "    $0 sourceCode.cpp [inputFile.in]"
    echo ""
    echo "Example:"
    echo "    $0 test.cpp"
    echo "    $0 test.cpp test.1.in"
    echo ""
    echo "This script compiles the C++ source code if the"
    echo "source is newer than the binary. Then pipe in the"
    echo "input if exists. Finally compare it with the output"
    echo "if exists."
else
    filename=$(basename "$1")
    extension="${filename##*.}"
    filename="${filename%.*}"

    if [ -z "$2" ]
    then
        casename=$filename
    else
        casename=$(basename "$2.in")
        casename="${casename%.*}"
    fi

    if [ ! -f "$filename" ] || [ "$1" -nt "$filename" ]
    then
        g++ -lm -Wall -Wconversion -g -O2 -std=c++11 -o $filename $1
    fi

    # run with input
    if [ $? -eq 0 ]
    then
        if [ -f "$casename.in" ]
        then
            if [ -f "$casename.out" ]
            then
                ./$filename < $casename.in | diff -y - $casename.out
            else
                ./$filename < $casename.in
            fi
        else
            ./$filename
        fi
    fi

fi