Mac OS X has fairly good memory management but it’s not perfect, and sometimes RAM can be held unnecessarily in the “inactive” state despite the contents no longer being needed. If you’ve been participating in memory heavy activities or you just need to free up some available RAM you can actually force Mac OS X to clear out inactive memory.

• Launch Terminal, found in /Applications/Utilities/ and enter the following command

purge

• Give OS X a minute or two to complete the process

Open Activity Monitor to see the before and after results yourself, you’ll find dramatic changes at the “Free”, “Used”, and “Inactive” meters under System Memory.

 

You may have noticed that “yum install apt” results in “nothing to do.” However, you can install it using YUM (centos uses YUM instead of APT). Since it requires downloading from a third party source (RPMforge). Please do so at your own risk.

Download and install the rpm forge release, which will enable YUM to access:
wget http://packages.sw.be/rpmforge-release/rpmforge-release-0.3.6-1.el5.rf.i386.rpm
rpm -i rpmforge-release-0.3.6-1.el5.rf.i386.rpm
After this is installed (it takes a long time), you can install APT.
You should now be able to use apt-get and install the apt repositories. You will have to add your sources at /etc/apt/sources.list.d