I have a text file with thousands of lines of hex values:

0x20000804

0x20001004 

0x20002004

0x20004004

0x20008004
etc etc
...
(For a few thousand lines)

Is there a way to do an invert grep expression to exclude the lines with a specific character in a specific index/position?

Example: With the numbers above in a .txt file, I only want to keep the lines that DO NOT have an "8" in index/position #6

Starting with:

0x20008034

0x20000804

0x20001004

0x20002004

0x20004004

0x20008004

I should get an output of:

0x20000804

0x20001004

0x20002004

0x20004004

As these lines do NOT have the character "8" in index/position 6