optijpg.sh

#!/bin/bash

#line break for "for"
IFS=`echo -en "\n\b"`

# Function to optimize a jpeg image.
function optimize() {
  ORIGINAL_FILE_SIZE=`du -b $1 | awk {'print $1'}`
  jpegtran -copy none -optimize -perfect -outfile "$1-opt" "$1"
  OPTIMIZED_FILE_SIZE=`du -b "$1-opt" | awk {'print $1'}`

  if [ $ORIGINAL_FILE_SIZE -gt $OPTIMIZED_FILE_SIZE ]
  then
    mv -f "$1-opt" "$1"
    echo -n '.'
  else
    rm "$1-opt"
    echo -n 'x'
  fi
}

if [ -z "$1" ]
then
  DIRECTORY="."
else
  DIRECTORY="$1"
fi

echo "[+] Optimizing jpegs under $DIRECTORY"
cd $DIRECTORY
STARTER_SIZE=`du -b $DIRECTORY | awk {'print $1'}`
echo "[i] Starting size: $STARTER_SIZE"


export -f optimize
PARALLEL_SHELL=/bin/bash \
  parallel --no-notice --env optimize optimize "{}" ::: `ls $DIRECTORY/*.jpg`
echo '';

END_SIZE=`du -b $DIRECTORY | awk {'print $1'}`
PERCENT=`echo "scale = 5;$END_SIZE/$STARTER_SIZE*100" | bc`
echo "[i] End size: $END_SIZE ($PERCENT%)"

IFS=$ORIGIFS