Grep4j does not find strings which start with "-". about grep4j HOT 4 CLOSED

I'm sorry, I used the wrong example.
Actually the string I want to use is "-format=', not '-encoding='.
(If you use '-encoding=', you will get some results.)

And one more thing I've just found. That is, Linux's grep command does not 
allow us to use strings such as '-format' and '-option' for the expression, 
and now I'm wondering if that corresponds to this issue.

Hi,

yes you cannot grep the string -format in linux as it's probably used as an 
internal keyword for the grep command itself.
I can think of couple of options for you:
1st is to use regex saying anything that starts with (^...):

GrepResults results = grep(regularExpression("^-format="),on(profile));

This will do it.

Or, as 2nd option, you can just use constantExpression and grep for format=
GrepResults results = grep(constantExpression("format="), local);

> #2
Thank you for your quick reply, and thank you very much for the helpful answer!
I used a regular expression ".*-format.*" (which is the 1st idea you gave me) 
and it works just perfect!