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Glossary

Marc Thielemann edited this page Oct 17, 2025 · 8 revisions



Installer package

A file with a .pkg file extension which is used on macOS. It normally contains an archive of files to install and information on where to install them. It can also include additional resources like Read Me or license documents, as well as scripts to run before or after the installation. There are two types of installer packages:

  • Component packages: these are the standard type of installer package, which contain an archive of files to install and the information on where the files should be installed.
  • Distribution packages: These packages can contain one or more component packages, and may also include additional resources to customize and control the user interface shown in the Installer application.

Payload-free installer package

Payload-free packages are installer packages for macOS that exist only to run scripts. They don't install any files, which would be referred to as the installer package's payload. With no payload included with these installer packages, the installer packages built by this tool are referred to as payload-free.


Notarization

Notarization is an additional safeguard against signed installer packages being modified by a malicious third party. The Apple notary service is an automated system that scans an installer package for malicious content and checks for code-signing issues, so notarization of a signed installer package ensures that Apple has passed the signed code through an automated scanning process and verified that the signed code is free of malicious content. macOS's security tools can check the notarization status of a signed and notarized installer package.


Installer package receipt

Installer package receipt files are used by macOS to maintain a record of what the Installer application has installed. Normally, a receipt file is created each time you install new software via a package file but there is an exception to this rule: payload-free packages normally do not install any files and do not leave a receipt behind. The receipt files will contain the following information:

  • Package identifier: This is a string which is used to uniquely identify an installer package.
  • Package version: This is a string used to store version information for the installer package.

Note

There is an option available to enable packages created by this app to leave a receipt, so that installation of the payload-free packages created by this app leave a receipt to help track their installation.

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