Question

I am new to Unix and I am having trouble understanding the grep command, specifically special characters tacked on to the end of the command. I did a bunch of research but I cannot find the right terminology to search on. My question is as follows:

What is the difference between these two commands?

grep -r "Something" .

grep -r "Something" *

Is there a name for the special characters at the end of the command? (ie * and .)

Are they part of a Regex?

Answer 1

.

means current directory

and

*

mean all files in the current directory

It have nothing to do with regex but with globs.

See http://wiki.bash-hackers.org/syntax/expansion/globs