It’s been almost eight years since I first updated Advanced Programming in the UNIX Environment, and already so much has changed. ? Before the second edition was published, The Open Group created a 2004 edition of the Single UNIX Specification, folding in the changes from two sets of corrigenda. In 2008, The Open Group created a new version of the Single UNIX Specification, updating the base definitions, adding new interfaces, and removing obsolete ones. This was called the 2008 version of POSIX.1, which included version 7 of the Base Specification and was published in 2009. In 2010, this was bundled with an updated curses interface and reissued as version 4 of the Single UNIX Specification. ? Versions 10.5, 10.6, and 10.8 of the Mac OS X operating system, running on Intel processors, have been certified to be UNIX? systems by The Open Group. ? Apple Computer discontinued development of Mac OS X for the PowerPC platform. From Release 10.6 (Snow Leopard) onward, new operating system versions are released for the x86 platform only. ? The Solaris operating system was released in open source form to try to compete with the popularity of the open source model followed by FreeBSD, Linux, and Mac OS X. After Oracle Corporation bought Sun Microsystems in 2010, it discontinued the development of OpenSolaris. Instead, the Solaris community formed the Illumos project to continue open source development based on OpenSolaris. For more information, see http://www.illumos.org.