bash function to watch if file size was changed for some period

watch_for_size_change.sh

#!/bin/bash

# function takes 2 arguments                                                                                                                                                
# $1 - file to watch for changes                                                                                                                                            
# $2 - how long to watch in seconds                                                                                                                                         
# it echoes "0" if file size was not changed during watching                                                                                                                
# and "1" if file does not exist or file size was changed                                                                                                                   
# example:                                                                                                                                                                  
# res=$(watch_for_size_change /path/to/file 10)                                                                                                                             
# ....                                                                                                                                                                      
watch_for_size_change() {
  SLEEP_TIME=1
  if [ -e $1 ]; then
    size=`du -bs $1`
    count=1
    sleep $SLEEP_TIME
    while [ $count -lt $2 ]; do
      new_size=`du -bs $1`
      if [ "$new_size" != "$size" ]; then
        echo "1";
        exit;
      fi;
      sleep $SLEEP_TIME
      let "count+=1"
    done;
    echo "0";
  else
    echo "1";
  fi;
}