sudo yum install [thing] keeps being unable to find the package I'm looking for. This includes simple things like 'sl', things like 'virtualenv', and 'gcc'.

My first instinct is to check my yum repos, but they seem to contain everything that they should from Red Hat. I've exhausted both my know-how and google's...

Try "yum search package_name" and see what results it showing...

And this IS in fact RHEL 6.5 or RHEL7.0 and not CentOS 6.5 or Centos 7.0

if it is redhat
you MUST buy the required license
now there is a 30 day free trial
BUT
you have to register the install !
--- a single desktop install is $299 per year for the standard one year contract
https://www.redhat.com/wapps/store/catalog.html

for gcc you install the software group
You might want to read , then reread the redhat documentation
https://access.redhat.com/documentat...erprise_Linux/

My university has a site-wide license. I'm 90% sure I followed the steps to register through the university, but I'll check it

can you please post the output of this

Red Hat Enterprises Linux Workstation release 6.5 (Santiago)
It was 6.4 upon installation, but I ran yum update about a week ago.

Show the output of 'yum repolist'.

Also, are you using RHN or RHSM? (iow, subscription-manager, or rhn_register). RHSM is pretty specific, so it has fine-grained access control over your repos.

I suggest using yum search, as well.

I am using RHN. Looking into it, I can confirm that I am subscribed to a RHN satellite update server through my university.

what pop's up with a yum search ?
also posting the output of
would help track down a problem

$ sudo yum repolist all
Loaded plugins: product-id, refresh-packagekit, rhnplugin, security,
: subscription-manager
This system is not registered to Red Hat Subscription Management. You can use subscription-manager to register.
This system is receiving updates from RHN Classic or RHN Satellite.
repo id repo n status
InstallMedia Red Ha disabled
adobe-linux-x86_64 Adobe enabled: 2
dl.atrpms.net_el6-x86_64_atrpms_stable added enabled: 3,330
rhel-source Red Ha disabled
rhel-source-beta Red Ha disabled
rhel-x86_64-workstation-6 Red Ha enabled: 13,602
rhel-x86_64-workstation-optional-6 RHEL W enabled: 6,213
rhel-x86_64-workstation-supplementary-6 RHEL W enabled: 368
rhn-tools-rhel-x86_64-workstation-6 RHN To enabled: 122
springdale.princeton.edu_data_puias_6.5_x86_64_os added enabled: 6,489
springdale.princeton.edu_data_puias_DevToolset_6.5_x86_64 added enabled: 246
repolist: 30,372

The GCC search produces a lot of results:

devtoolset-1.0-gcc.x86_64 : GCC version 4.7
devtoolset-1.0-gcc-c++.x86_64 : C++ support for GCC version 4.7
devtoolset-1.0-gcc-debuginfo.x86_64 : Debug information for package
: devtoolset-1.0-gcc
devtoolset-1.0-gcc-gfortran.x86_64 : Fortran support for GCC 4.7
devtoolset-1.0-gcc-plugin-devel.x86_64 : Support for compiling GCC plugins
devtoolset-1.1-gcc.x86_64 : GCC version 4.7
devtoolset-1.1-gcc-c++.x86_64 : C++ support for GCC version 4.7
devtoolset-1.1-gcc-debuginfo.x86_64 : Debug information for package
: devtoolset-1.1-gcc
devtoolset-1.1-gcc-gfortran.x86_64 : Fortran support for GCC 4.7
devtoolset-1.1-gcc-plugin-devel.x86_64 : Support for compiling GCC plugins
devtoolset-2-gcc.x86_64 : GCC version 4.8
devtoolset-2-gcc-c++.x86_64 : C++ support for GCC version 4.8
devtoolset-2-gcc-debuginfo.x86_64 : Debug information for package
: devtoolset-2-gcc
devtoolset-2-gcc-gfortran.x86_64 : Fortran support for GCC 4.8
devtoolset-2-gcc-plugin-devel.x86_64 : Support for compiling GCC plugins
gcc-c++.x86_64 : C++ support for GCC
gcc-gnat.x86_64 : Ada 95 support for GCC
gcc-java.x86_64 : Java support for GCC
gcc-objc.x86_64 : Objective-C support for GCC
gcc-objc++.x86_64 : Objective-C++ support for GCC
libgcc.i686 : GCC version 4.4 shared support library
libgcc.x86_64 : GCC version 4.4 shared support library
mingw32-gcc.x86_64 : MinGW Windows cross-compiler (GCC) for C
compat-gcc-34.x86_64 : Compatibility GNU Compiler Collection
compat-gcc-34-c++.x86_64 : C++ support for compatibility compiler
compat-gcc-34-g77.x86_64 : Fortran 77 support for compatibility compiler
devtoolset-1.0-libquadmath-devel.x86_64 : GCC 4.7 __float128 support
devtoolset-1.1-libquadmath-devel.x86_64 : GCC 4.7 __float128 support
devtoolset-2-libquadmath-devel.x86_64 : GCC 4.8 __float128 support
gcc.x86_64 : Various compilers (C, C++, Objective-C, Java, ...)
gcc-gfortran.x86_64 : Fortran support
libgcj.i686 : Java runtime library for gcc
libgcj.x86_64 : Java runtime library for gcc
libgcj-devel.i686 : Libraries for Java development using GCC
libgcj-devel.x86_64 : Libraries for Java development using GCC
libgcj-src.x86_64 : Java library sources from GCC4 preview
libgomp.i686 : GCC OpenMP v3.0 shared support library
libgomp.x86_64 : GCC OpenMP v3.0 shared support library
libmudflap.i686 : GCC mudflap shared support library
libmudflap.x86_64 : GCC mudflap shared support library
libmudflap-devel.i686 : GCC mudflap support
libmudflap-devel.x86_64 : GCC mudflap support
mingw32-gcc-c++.x86_64 : MinGW Windows cross-compiler for C++
mingw32-gcc-gfortran.x86_64 : MinGW Windows cross-compiler for FORTRAN
mingw32-gcc-objc.x86_64 : MinGW Windows cross-compiler support for Objective C
mingw32-gcc-objc++.x86_64 : MinGW Windows cross-compiler support for Objective
: C++

so it is working

install the development group
or
use the 100% by chance "short cut"
but using the development group is preferred
to see a list of software groups that can be installed see

Development tools shows up as a group that is already installed.
Running yum install gcc++ gives me:
No package gcc++ available.

Doing a sanity check, I still have
$ gcc --version
gcc (GCC) 4.4.7 20120313 (Red Hat 4.4.7-4)

and yet
$ cat /etc/redhat-release yields
Red Hat Enterprise Linux Workstation release 6.5 (Santiago)

:/

So run `yum install gcc-c++`.

Won't that give you what you need?

There is no 'gcc++' package in our stock repos, so yum is correct (not even in dev-tools).

But it looks like if you want C++ libs for GCC, then you should install 'gcc-c++'. If you want regular GCC, then 'gcc.[arch]', where [arch] is x86_64 or god forbid, i686.

Also, 4.4.7-4 is the correct version for RHEL 6.5 for both GCC as well as GCC C++.