Learn to use grep's extended regular expressions to describe more complex patterns. The ?
and +
special characters describe optional patterns. The ?
character matches zero or one instance of the preceding term, and the +
character matches one or more instances of the preceding term. To use these characters, you'll need to either escape them with backslashes or turn on extended regular expressions with the -E
flag.
I dont understand why we need to scape these characters and not the single dot "." character?