A bash script for adding build tags to an ELF file

elftagger.sh

#!/bin/bash

date_format_str=""
git_describe=""
user_name=""
version_str=""

while getopts "d:g:u:v:h?" opt; do
    case "$opt" in
        d)
            date_format_str=$OPTARG
            ;;
        g)
            git_describe=$OPTARG
            ;;
        u)
            user_name=$OPTARG
            ;;
        v)
            version_str=$OPTARG
            ;;
        h|?)
            echo "Help!! Please write a help string"
            exit
            ;;
    esac
done
shift $((OPTIND-1))

tmpfile=$(mktemp)
echo "BuildTags ver0.1" >> $tmpfile
if [[ ! -z "$date_format_str" ]]; then
    echo "Build Time:" $date_format_str >> $tmpfile
fi
if [[ ! -z "$git_describe" ]]; then
    echo "Git Describe:" $git_describe >> $tmpfile
fi
if [[ ! -z "$user_name" ]]; then
    echo "using user name"
    echo "User Name:" $user_name >> $tmpfile/tmp/tmp.urNJtFf7cf
fi
if [[ ! -z "$version_str" ]]; then
    echo "Version:" $version_str >> $tmpfile
fi
if [[ -z "$1" || ! -f $1 ]]; then
    echo "File does not exist. Exiting"
    exit
fi


tmpfile_elf=$(mktemp)
objcopy --add-section BuildTags=$tmpfile $1 $tmpfile_elf
mv $tmpfile_elf $1.new