Yes, you will need the GNU grep. Personally I do not miss the "-r" flag because you can do the same with a combination of
grep but this reminds that having the GNU tools available on your Solaris box is what I would consider best practice. So here we go:
I wouldn't go about downloading source code from various places on the Internet and then building yourself. That is not necessary. If you simply want your Solaris to have the typical GNU tools available then do as follows:
If you are on Solaris 10 you should get the Solaris 10 Companion Disk. This used to be distributed by Sun but it now lives here. Personally I would make it a habbit always to install the contents of this disk or at least the most important GNU parts. Make it part of your JumpStart (or whatever you use) for new servers in your organisation !
If you are on Solaris 11 life is a lot simpler. The GNU tools are typically installed by default but do not all of them get propagated into local zones. IFS, the packaging system on Solaris 11, makes your life a lot easier so you really should be moving to Solaris 11 (lots of other reasons as well). The list of packages that you should consider always to have available for any zone are these:
and if you use the host for development/build purpose you might want to add:
Personally I would make the above (potentially less the dev tools) part of my company's default install for new servers / zones. Solaris sysadmins often insist on being different from Linux world but there's really no need to. Just do it and make it part of your default install. You won't regret it.