The script to monitor a folder for uploaded file and their compression.

upload.sh

#!/bin/bash

# Use the newline character
# as the field separator.
IFS=$'\n'

# The folder to watch.
dir="/home/bbf/upload/"

# Get the folder's content, recurively.
for item in $(find "${dir}")
do

        # If the item is a regular file.
        if [ -f "${item}" ]
        then
        
                # Check if the file is in use by someone else.
                lsof -n "${item}" > /dev/null
                
                # If no one is using the file.
                if [ "$?" -ne 0 ]
                then
                
                        # Get the file extension.
                        ext=$(echo "${item}" | awk -F "." '{ print $NF }')
                        
                        # If the file is not a zip archive
                        # and does not exists a zip archive fo it
                        if [ "${ext}" != "zip" -a ! -f "${item}.zip" ]
                        then
                                # Create the zip archive but
                                # do not compress it (store it).
                                zip -0 "${item}.zip" "${item}" > /dev/null
                        fi
                        
                fi
                
        fi
        
done