Using the Mac's Hidden Archive Utility to Control Compression

The macOS' Finder uses the system's built-in Archive Utility to perform compression (archiving) and expansion of files in the background without opening a window for the utility itself. It relies on several preconfigured defaults: As installed, the Finder always uses the ZIP format and always saves archives in the same folder as the original. You can change these defaults for a bit more control over the archive format, what happens to the original files, and where expanded or compressed files are stored by using the Archive Utility directly.

Launch the Archive Utility Preferences

You'll find the Archive Utility in your computer's System folder at /System/Library/CoreServices/Applications (or at /System/Library/CoreServices in pre-Yosemite versions).

Archive Utility opens without presenting a window; instead, there's just a set of menus along the top of the screen. To change the utility's defaults, open Archive Utility > Preferences.

Manage Archive Utility Preferences

The Preferences window is broken into two sections: one for expanding files, and the other, for compressing them.

Expansion Options

The options for expanding files are:

Save expanded files: Select where you want to store expanded files on your Mac. The default location is the same folder that holds the archived file you're expanding. To change the destination for all file expansions, click the arrows to the right and navigate to the desired destination folder.

After expanding: This specifies what happens to the original file after it's expanded. The default action is to leave the archive file in its current location (leave archive alone), or you can choose from the drop-down menu to instead move the archive file to the trash, delete the archive, or move the archive file to specific folder. If you choose the last option, you are directed to navigate to the target folder. Remember, this folder will be used as the target location for all archived files that you expand. You can change your selections at any time, but it's usually simpler to select one location and stick to it.

Reveal expanded item(s) in Finder: When checked, this option causes the Finder to highlight the files you expanded. This can be handy when the files in an archive have different names than what you were expecting.

Keep expanding if possible: This box is checked by default and tells the Archive Utility to keep expanding items it finds within the archive. This is helpful when an archive contains other archives.

Compression Options

The configurable options for compression are:

Save archive: This drop-down menu controls where the archive file is stored after the selected files are compressed. The default is to create the archive file in the same folder where the selected files are located. If desired, select the Into option to pick a destination folder for all created archives.

Archive format: The Archive Utility supports three compression formats.

• Compressed archive, which is the same as a UNIX compression method called cpgz.
• Regular archive, also known in the UNIX world as cpio. This method actually doesn't perform any compression; instead, it just creates a container file made up of all of the selected files.
• ZIP is the final option, and the one most Mac users are familiar with. This is the standard ZIP format that has been used on Mac and Windows computers for years.

After archiving: Once you finish archiving files, you can leave the files alone, which is the default option; move the files to the trash; delete the files; or move the files to a folder of your choice.

Reveal archive in Finder: When checked, this box will cause the archive file to be highlighted in the current Finder window.

Use the Archive Utility to Compress Files

Launch Archive Utility, if it's not already open.

1. Select File in the Archive Utility menu bar and choose Create Archive.

2. A window opens that you can use to navigate to the folder that contains the items you want to compress. Make your selection and then click Archive.

Use the Archive Utility to Expand an Existing Archive

1. Select File in the Archive Utility menu bar and choose Expand Archive.

2. A window opens that you can use to navigate to the folder that contains the archive you want to expand. Make your selection, and then click Expand.