# Pacifist overview

Pacifist is an application which can:

- Open up Mac OS X installer packages (.pkg and .mpkg) and extract individual files from them
  Pacifist allows you to pull just one file out of a package without having to run the whole installer. This can come in handy if your copy of one of the applications supplied with Mac OS X, such as Mail, iChat, or System Preferences, becomes damaged and you would like to reinstall it without having to reinstall Mac OS X in its entirety.
- Open up many other common archive types found on Mac OS X
  In addition to installer packages, Pacifist can open and extract files from a wide variety of other formats, including .zip, .dmg, .tar, .tar.gz, .tar.bz2, .cpio, .cpio.gz, .cpio.bz2, and .xar archives.
- Open some archive types directly over the World Wide Web
  Pacifist can open some archive types, including .zip and .xar archives, directly over HTTP. This allows you to extract an individual file from an archive without having to wait for the entire archive to download. Pacifist can also load .pkg installer packages over HTTP, although extracting from the package contents will require longer downloads than .zip and .xar archives.
- Verify existing installations
  Pacifist can examine an installer package, and scan your hard disk to determine whether all the files in the package are installed. You can be notified of any files from the package which are not present on the disk, as well as any files whose checksums or permissions do not match what is specified in the package*.
- Examine kernel extensions
  Pacifist can scan the contents of your /System/Library/Extensions folder to determine which kernel extensions were installed by the operating system, and which may have been put there by a third-party application.

*This product includes software developed by the University of California, Berkeley and its contributors.