Watch directory A, and copy into directory B when something in directory A changes.

directory_monitor.sh

#!/bin/sh
#Simple script to watch directory, and when something changes copy all of contents of directory A into directory B
#Requires: md5
#Tomasz Malisiewicz

#the directory to watch
SOURCE_DIR=/tmp/input/

#the directory we copy files into
TARGET_DIR=/tmp/output/

#the temporary file we use to monitor directory contents
#NOTE: this has to be different for each directory you want to monitor
TEMP_FILE=/tmp/list

#how many seconds to wait before checking directory contents
SLEEP_TIME=1

touch ${TEMP_FILE}
while [ true ]
do
    
    F=`ls -l ${SOURCE_DIR} | md5`    
    O=`cat ${TEMP_FILE}`
    if [ "$F" = "$O" ]
    then
        echo "not changed"
    else
        echo "Copying files"
        cp $SOURCE_DIR/* $TARGET_DIR
    fi
    echo $F > $TEMP_FILE
    sleep ${SLEEP_TIME}
done