This script appends an automatically generated include guard to a specified header file. Optionally, you can provide a prefix that will be added to the guard macro.

guardhdr.sh

#!/bin/bash

if [ "$#" = "0" ]; then
	echo "at least one argument is required"
	exit 1
fi

FILE=$1
GUARD="$2$(printf "%s" $FILE | tr '.' '_' | tr '[[:lower:]]' '[[:upper:]]')"

cat <<EOF >> $FILE

#ifndef $GUARD
#define $GUARD



#endif /* $GUARD */

EOF