echo “#!” fails — “event not found”

Question

The following fails and I don\'t understand why:

$ echo \"#!\"

the following also fails with the same error message:

$ echo         


        

Answer 1

echo '#!'

Basically, with double quotes (") aka "weak quoting", Bash does some wacky things with the string, like variable substitution. With single (') aka "strong quoting" the string is taken literally.

See e.g. here for a more in-depth explanation of quoting.