#...

template_file="~/mytest_template.c";

if [[ -z $template_file ]]; then
   echo -e "#include <stdio.h>n#include <stdlib.h>nnnint main(int argc, char**argv){nntnnreturn 0;n}" > ~/mytest_template.c;
fi

#sleep 0.5; ---> I tried this too.

cp ~/mytest_template.c mytest.c;