Q:

Download different version of grep in cygwin? 

I'd like to download a different version of grep in Cygwin.  Currently, I have version 2.21, but I'd like to get version 2.5.1 (this is what runs on Mac OS by default, and I'm more familiar with that). 
I obviously don't want to run the entire setup again.   Is  there a way to get the Mac OS version (i.e. 2.5.1)  without running setup all over again?   Thanks.  <3

A:

Compiling is always a possible choice: grep lives here: ftp://ftp.gnu.org/gnu/grep/, and given the tarball (ftp://ftp.gnu.org/gnu/grep/grep-2.5.1.tar.gz), 
tar xf 2.5.1.tar.gz
cd 2.5.1
./configure
make && make install

(this will probably install into /usr/local/bin — you should read the instructions, e.g., the --prefix option to suit your own needs). 
That assumes you are developing, and have installed gcc (the Cygwin setup program helps in that case).