Installer (OS X)

From Wikipedia, the free encyclopedia
  (Redirected from Installer (Mac OS X))
Jump to: navigation, search
Mac OS X Installer.png
Installer Screenshot.png
Installer 6.1.0 running on OS X Yosemite
Developer(s) Apple Inc.
Stable release 6.1.0 / October 16, 2014; 11 months ago (2014-10-16)[1]
Operating system OS X
Type Package management system
License Proprietary

Installer is an application included in OS X (and in its progenitors OPENSTEP and NeXTSTEP) that extracts and installs files out of .pkg packages. It was created by NeXT, and is now maintained by Apple Inc. Its purpose is to help software developers create uniform software installers.

Installer resides at /Applications/Utilities/ on Macintosh computers running OS X versions prior to 10.5, and launches when a package or metapackage file is opened. In OS X Yosemite, the Installer application is located at /System/Library/CoreServices/ The installation process itself can vary substantially, as Installer allows developers to customize the information the user is presented with. For example, it can be made to display a custom welcome message, software license and readme. Installer also handles authentication, checks that packages are valid before installing them, and allows developers to run custom scripts at several points during the installation process.[2]

There is also a command line version located at /usr/sbin/installer.[3]

Installer package[edit]

Installer packages have the file extension .pkg. Prior to OS X 10.5, installer packages were implemented as OS X packages.[4] These packages were a collection of files that resided in folders with a .pkg file extension.[5][6] In OS X 10.5 the software packaging method was changed to use the XAR (eXtensible ARchiver) file format; the directory tree containing the files is packaged as an xar archive file with a .pkg extension.[7] Instead of distributing multiple files for a package, this allowed all of the software files to be contained in a single file for easier distribution with the benefit of package signing.

See also[edit]


  1. ^ "OS X 10.10 Yosemite release date". Retrieved 16 November 2014. 
  2. ^ Package maker user guide
  3. ^ Command line installer man page
  4. ^ "Software Delivery Guide". Apple. Retrieved 15 March 2015. 
  5. ^ "The Flat Package". MacTech. Retrieved 15 March 2015. 
  6. ^ "OSX legacy packaging redux". Matthew Brett. Retrieved 15 March 2015. 
  7. ^ "XAR NEW MacOS X 10.5 package format". MacGeekBlog. Retrieved 15 March 2015.