Append to file only if it exists

Question

I\'ve seen several answers on SO about how to append to a file if it exists and create a new file if it doesn\'t (echo \"hello\" >> file.txt) or overwrite

Answer 1

Just check:

if [ -f file.txt ]; then
  echo "hello" >> file.txt
else
  echo "No file.txt" >&2
  exit 1
fi

There's no way in bash to alter how >> works; it will always (try to) create a file if it doesn't already exist.