dopptx.sh

#!/usr/bin/env bash

function dopptx {
    source_folder=$(basename -- $1)
    tmp_folder="${source_folder}_tmp"
    slides_name="${source_folder%%_*}.pptx"
    
    cp -r $source_folder $tmp_folder

    find $tmp_folder -type f -name "*.xml" -exec  sh -c "cat {} | xmllint --noblanks - | sponge {}" \;
    find $tmp_folder -type f -name "*.rels" -exec  sh -c "cat {} | xmllint --noblanks - | sponge {}" \;

    cd ./$tmp_folder; zip -qq -r -X ../$slides_name *

    cd ..; rm -rf ./$tmp_folder
}

for d in *_slides/ ; do
    dopptx "$d"
done

unpptx.sh

#!/usr/bin/env bash

function unpptx {
    filename=$(basename -- $1)
    source=$1
    folder="${filename%.*}_slides"

    unzip -qq -o -d $folder $source

    find ./$folder -type f -name "*.xml" -exec  sh -c "cat {} | xmllint --format - | sponge {}" \;
    find ./$folder -type f -name "*.rels" -exec  sh -c "cat {} | xmllint --format - | sponge {}" \;
}

for i in `find . -name "*.pptx" -type f`; do
    unpptx "$i"
done