tar-jpeg-optimizer.sh

#!/bin/bash

set -e

INPUT=$(realpath "$1")
INPUT_PATH=$(dirname "$INPUT")
TMP_DIR=$(mktemp -d -t tar-extract-XXXXX)
SRC_TMP_DIR="$TMP_DIR/in"
DST_TMP_DIR="$TMP_DIR/out"

mkdir -p "$SRC_TMP_DIR"
mkdir -p "$DST_TMP_DIR"

# Extract the archive
tar -xf $1 -C "$SRC_TMP_DIR"

while IFS= read -r -d $'\0'; do
    FILE="$REPLY"
    FILE_PATH=$(dirname $FILE)
    FILE_NAME=$(basename "$FILE")
    REL_PATH=$(realpath --relative-to="$SRC_TMP_DIR" "$FILE_PATH")
    mkdir -p "$DST_TMP_DIR/$REL_PATH"
    if [[ $(file -b "$FILE") =~ JPEG ]]; then
        # JPEG FILE
        mozjpeg -progressive -quality 75 "$FILE" > "$DST_TMP_DIR/$REL_PATH/$FILE_NAME"
    else
        cp "$FILE" "$DST_TMP_DIR/$REL_PATH/$FILE_NAME"
    fi;
done < <(find "$SRC_TMP_DIR" -type f -print0)

pushd "$DST_TMP_DIR"
tar -cvf "$INPUT_PATH/optimized-$1" *
popd

rm -rf "$TMP_DIR"