Resizes and renames image files in the current directory using sips (osx). Can be rewritten to imagemagick easily to make it work on Linux too.

resize-images.sh

# Given a collection of image files, this function will resize
# the images in the current folder and saves them in the subfolder resized
#
# Usage: resize-images
# Note: the read command is specific for ZSH shells, for Bash, use -p param. Same for the setopt, it's shopt for bash.
#
## Resize and rename images in the current directory and writes them to a resized subfolder
function resize-images() {
  read "filename?What would you like the filename to be started with? []: "
  read "width?What max width in pixels would you like your images? [1024]: "
  read "height?What max height in pixels would you like your images? [768]: "

  width=${width:-1024}
  height=${height:-768}

  echo
  echo "All images will be renamed to $filename-xx.jpg with a maximum resolution of $width x $height pixels."
  echo

  mkdir -p resized

  # start renaming and resizing the images
  count=1
  total=$(find . -type f \( -name "*.jpg" -or -name "*.jpeg" -or -name "*.JPG" -or -name "*.JPEG" \) -maxdepth 1 | wc -l | sed 's/ //g')

  # shopt in bash
  setopt nullglob nocaseglob

  for file in *.jpg *.jpeg
  do
    # rename
    new=$(printf "${filename}_%03d.jpg" $count)
    echo
    echo "($count/$total) Processing $file and renaming to $new..."
    echo

    cp $file $new

    # resize and move
    sips --resampleHeightWidth $height $width --setProperty formatOptions 80 $new --out resized/

    # remove temp file
    rm $new

    let count=count+1
  done

  # open the directory in Finder
  open resized/
}