using escapes

me@box:~$ cat demo.txt

The price is $5.00 per unit, for a total of $50.

me@box:~$ cat demo.txt | egrep ‘$’

The price is $5.00 per unit, for a total of $50.

me@box:~$ cat demo.txt | egrep ‘$[0-9]*’

me@box:~$ cat demo.txt | egrep ‘\$[0-9]*’

The price is $5.00 per unit, for a total of $50.

me@box:~$ cat demo.txt | egrep ‘\$[0-9]*.[0-9]*’

The price is $5.00 per unit, for a total of $50.

me@box:~$ cat demo.txt | egrep ‘\$[0-9]*\.[0-9]*’

The price is $5.00 per unit, for a total of $50.

me@box:~$ cat demo.txt | egrep ‘\$[0-9]*\.[0-9]+’

The price is $5.00 per unit, for a total of $50.