Batch convert NEF to jpg in Linux/macOS [Prerequisites: ImageMagick, ufraw-batch]

batch_convert.sh

#!/bin/bash
# Change to directory at first argument or use the current folder
if [ ! -z "$1" ]; then
  cd "$1"
fi

mkdir -p jpeg
for file in *.NEF; do
  filename="${file%.NEF}.jpg"
  echo "Converting $file to $filename"
  # Add these flags to convert and attempt auto enhancement
  # --channel rgb -auto-level -enhance -equalize -contrast
  convert $file $filename
  mv $filename jpeg/ 2>/dev/null
  rm $file
done

What does jpeg/ 2>/dev/null mean?