Mathematica "prelude"

There are several configuration files that you can use to load functionality at startup. They have the form

($BaseDirectory | $UserBaseDirectory)/(Kernel | FrontEnd)/init.m

where

$BaseDirectory 

is for every user on the system and

$UserBaseDirectory

is for you along and Kernel or FrontEnd specifies what you are configuring. In fact, a lot of the settings under the Preferences menu automatically write to $UserBaseDirectory/FrontEnd/init.m.

In your case, you are looking to add to $UserBaseDirctory/Kernel/init.m.

With $UserBaseDirectory/Kernel/init.m the most obvious place to put code which should be autoloaded has been mentioned.

But I think it might be worth mentioning that there is also the Autoload directory within $UserBaseDirectory where you can put any package file or package directory and those will automatically be loaded at startup. For the purpose mentioned I think that might be an even better place (after having the code set up as a proper package of course...).

---

Note that init.m files and Autoload packages are loaded during kernel initialization when certain functions, such as Throw/Catch, cannot be safely evaluated. A lot of complex functionality depends on these, and is therefore unsafe to use in init files. It is generally best to limit initialization files to issuing definitions and basic operations.

---

The initialization is done in this order:

• load paclet manager
• load $BaseDirectory/Kernel/init.m
• load $UserBaseDirectory/Kernel/init.m
• load files passed with the -initfile command line option
• load Autoload packages

The loading is triggered in SystemFiles/Kernel/SystemResources/$SystemID/sysinit.m, which you can examine for more information on the initialization process. Some documentation is here.

Subkernels used by the parallel tools are launched with -noinit, so they don't load the standard Kernel/init.m files. They do load Autoload packages.