Mac OSX (El Capitan) Software Update tool via CLI

List available software updates via CLI (but don't install them):

$ sudo softwareupdate -l
Software Update Tool
Copyright 2002-2015 Apple Inc.

Finding available software
Software Update found the following new or updated software:
   * OS X El Capitan Update-10.11.5
OS X El Capitan Update (10.11.5), 740450K [recommended] [restart]
   * RAWCameraUpdate6.19-6.19
Digital Camera RAW Compatibility Update (6.19), 7575K [recommended]
   * iTunesXPatch-12.4
iTunes (12.4), 144804K [recommended]



Install all pending software updates via CLI:

$ sudo softwareupdate -i -a
Software Update Tool
Copyright 2002-2015 Apple Inc.

Finding available software

Downloading OS X El Capitan Update
Downloading Digital Camera RAW Compatibility Update
Downloading iTunes
Downloaded Digital Camera RAW Compatibility Update
Downloaded iTunes
Downloaded OS X El Capitan Update
Installing OS X El Capitan Update, Digital Camera RAW Compatibility Update, iTunes
Done with OS X El Capitan Update
Done with Digital Camera RAW Compatibility Update
Done with iTunes
Done.

You have installed one or more updates that requires that you restart your

computer.  Please restart immediately.