grep pattern single and double quotes

Question

Is there any difference between enclosing grep patterns in single and double quotes?

grep "abc" file.txt

and

grep 'abc' file.txt

I'm asking since there's no way I could test all possible cases on my own, and I don't want to stumble into a case that I get wrong :)

Answer 1

I see a difference if you have special characters :

Ex :

grep "foo$barbase" file.txt

The shell will try to expand the variable $barbase, this is maybe not what you intended to do.

If instead you type

grep 'foo$barbase' file.txt

$bar is taken literally.

Finally, always prefer single quotes by default, it's stronger.