Bash script for webpage changes monitoring

I wrote a simple bash script for monitoring changes in a webpage. I was able to find a couple or more such scripts on the web but non of those worked for https websites with non-valid cerfificates. So here is one that does:

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
#!/bin/bash

while true; do

if [[ -f new_page.html ]]; then
  mv new_page.html old_page.html
fi
wget --tries=45 --wait=10 $1 -O new_page.html --no-check-certificate > /dev/null 2>&1
diff ./new_page.html ./old_page.html > /dev/null
if [[ $? -ne 0 ]]; then
  echo "The webpage has changed!"
  date
  # mpg123 -q /home/user/latin_rhythm_guitar.mp3
  firefox $1
else
  echo "No change"
  date
fi
# sleep some time
sleep 1800
done

The line mpg123 -q /home/user/latin_rhythm_guitar.mp3 is commented out. If you choose to play a song each time a change in the webpage occurs change the filename and un-comment.

Part of the source code is from the script found here.