MacOS – MacVim — how to make Ctrl+A go to beginning of line, Ctrl+E to the end of the line

The default shortcuts for moving to beginning or end of (wrapped) lines are ⌘← and ⌘→. ⌥↑ and ⌥↓ or ⌃A and ⌃E move to the beginning or end of unwrapped lines (or paragraphs). ⌥← and ⌥→ move backwards/forward by words, and all of these are compatible with holding Shift to select during the corresponding moves.

You could remap home and end by creating ~/Library/KeyBindings/ and saving a property list like this as DefaultKeyBinding.dict:

{
    "\UF729"  = moveToBeginningOfLine:; // home
    "\UF72B"  = moveToEndOfLine:; // end
    "$\UF729" = moveToBeginningOfLineAndModifySelection:; // shift-home
    "$\UF72B" = moveToEndOfLineAndModifySelection:; // shift-end
}

Most of the keybindings for editing text in OS X are defined in /System/Library/Frameworks/AppKit.framework/Resources/StandardKeyBinding.dict.

Applying changes requires reopening applications. DefaultKeyBinding.dict is ignored by some old versions of Xcode (works with latest version 6.3.1), Terminal, and many cross-platform applications.

See Cocoa Text System and my website for more information about the customizable keybindings.

Terminal's keybindings can be customized in Preferences > Settings > Keyboard. \033OH moves to the beginning of a line and \033OF to the end of a line.

In Eclipse, key bindings should be modified in Preferences > General > Keys. You need to modify default bindings for commands Line Start and Line End (replace ⌘← by ↖ and ⌘→ by ↘). For selection to work, also modify Select Line Start and Select Line End.

PS: You may need to logout and login again for the ~/Library/KeyBindings/DefaultKeyBinding.dict change to take effect.

Here's how you can get ⌃ Control+arrow keys to work like you describe. Copy the following property list into ~/Library/KeyBindings/DefaultKeyBinding.dict (you can create the directory if it doesn't already exist):

{
    "^\UF703" = ("moveWordForward:", "moveWordForward:", "moveWordBackward:");
    "^$\UF703" = ("moveWordForwardAndModifySelection:", "moveWordForwardAndModifySelection:", "moveWordBackwardAndModifySelection:");
}

This will set up ⌃ Control+arrow to navigate to the beginning of the next word (by using OS X's normal navigation three times: to the end of the current word, end of the next word, then back to the beginning of the next word). I also included a version that works with ⇧ Shift so you can select text as you go.

Caveat: this will only work in Cocoa apps, but I think the normal ⌥ Option+arrow navigation does too. Also, make sure to relaunch your apps!