Quotes when using grep?

Question

Grep acts differently depending on what kind of quotes I surround the regex with. I can\'t seem to get a clear understanding of why this is. Here is an example of the problem:

Answer 1

In order:

grep -e show( test.txt

does not work, because the shell interprets the ( as special, a parenthesis, not just a character, and can't find the closing ).

These both work:

grep -e 'show(' test.txt
grep -e "show(" test.txt

because the shell treats the quoted text as just text, and passes it to grep.

These do not work:

grep -e 'show\(' test.txt
grep -e "show\(" test.txt

because the shell passes show\( to grep, grep sees \( as special, a parenthesis, not just a character, and can't find the closing \).