Applejack includes memtest as an optional install.
http://www.macupdate.com/info.php/id/15667/
http://sourceforge.net/projects/applejack
AppleJack is a user friendly command line tool for troubleshooting Mac OS X. With AppleJack you can perform basic troubleshooting on a computer even if you can't load the GUI, or don't have a startup CD handy. AppleJack runs in Single User Mode and is menu-based for ease of use.
This package installs the following files:
/private/var/root/Library/Scripts/applejack.sh - the AppleJack script
/usr/share/man/man8/applejack.8 - man page for AppleJack
/Library/Documentation/AppleJack - ReadMe and License files
Additionally, if you choose 'Customize' during the installation process, you can choose to have the following files installed as well:
/usr/local/sbin/memtest - the memtest memory testing program
/usr/share/man/man8/memtest.8 - man page for memtest
/Library/Documentation/memtest414 - the documentation for memtest
The installer also modifies the root user's profile (/var/root/.profile) in order to create a friendly usage reminder message and alias at startup in single user mode.
After the installation is complete, type 'man applejack' in a Terminal window to get more information. I also recommend you print out the ReadMe document while you are installing AppleJack. It will likely save you a lot of head scratching once you endeavor to strike out beyond the basic applejack auto restart command.
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Memtest OSX
This is a distribution of Tony Scaminaci's Memtest OS X program (version 4.14). It allows you to check almost all available RAM for hardware errors. If installed together with AppleJack, you can use AppleJack's expert mode to easily run memory tests while in single user mode. See
http://www.memtestosx.org for more info.