Is there a way to grep all lines that do NOT have somethign in them?

So if I had lines:

#Hi my name is
Blah Blah
#ok thanks

And I want to grep the file to only display all lines that don't have a # in them is that possible? And if so what is the command to do it?

From man grep:

-v, --invert-match
Invert the sense of matching, to select non-matching lines.

so, to find lines that do NOT contain "foo":
grep -v foo

--Rounan

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Here's an example. You need to escape the # because it's a special character.

cat test.txt | grep -v "#"

note that # is a special character & needs to be escaped. <edit> or quoted.