Shell Programming and Scripting

ls

while true
do
        if [ ! -f filename ]
        then
                sleep 300
        else
                ./scriptname
                break
        fi
done

nohup watch -n300 "test -f /path/to/your/directory/*.*; if [ $? -eq 0 ]; then /your/script; else :; fi" &> /dev/null &

#!/bin/bash
until ls * ; do sleep 300; done    # Wait until a file is present
while true    # Wait until the file stops growing
do
    X="$(ls -l)"
    [ "$X" = "$Y" ] && break
    Y="$X"
    sleep 1
done
# Put your code here