macOS Applications, File Types, and System Folders for A+
Short answer
- .dmg: Disk images that when opened mount as a volume. Technicians should expect to drag an .app out of a mounted .dmg to /Applications or run an included installer. - .pkg: Installer packages that run Installer and may alter multiple system locations; often require admin credentials. Uninstallation may require a provided uninstaller or manual removal of installed files. - .app: Application bundles that can often be installed by copying to /Applications and removed by deleting the bundle; some apps create additional support files in /Library or ~/Library. - App Store: Installs and updates are managed and tied to an Apple ID.
Why it appears on the exam
- Identify which package type mounts as a volume (.dmg) versus which runs Installer (.pkg). - Given a symptom isolated to one user, choose whether to inspect ~/Library or /Library first. - Determine the correct uninstall approach for an App Store app vs a web-downloaded .app.
Key concepts
Concept 1
Required terms
.dmg: A disk-image container file commonly used to distribute macOS applications; mounting a .dmg presents a virtual volume. .pkg: A macOS installer package that runs an installer script to place files and possibly run pre/post-install actions. .app (application bundle): A directory presented as a single application file in Finder; contains executable and resources. App Store: Apple's curated distribution channel for macOS apps with managed installation, updates, and license ties to Apple ID.
Example
Installing an app downloaded as a .dmg: double-click .dmg, drag the .app to /Applications, eject the mounted image.
Concept 2
How macOS Applications, File Types, and System Folders works
- .dmg: Disk images that when opened mount as a volume. Technicians should expect to drag an .app out of a mounted .dmg to /Applications or run an included installer. - .pkg: Installer packages that run Installer and may alter multiple system locations; often require admin credentials. Uninstallation may require a provided uninstaller or manual removal of installed files. - .app: Application bundles that can often be installed by copying to /Applications and removed by deleting the bundle; some apps create additional support files in /Library or ~/Library. - App Store: Installs and updates are managed and tied to an Apple ID.
Example
Installing a .pkg: double-click runs Installer, follow prompts, may require administrator password.
Concept 3
Common confusion
- Confusing .dmg and .pkg. Remember: .dmg is a container; .pkg is an installer. - Thinking deleting an .app always fully uninstalls it. Many apps leave files in /Library or ~/Library. - Expecting to freely modify /System; recent macOS versions protect /System for integrity.
Example
Removing an app installed from App Store: delete from Launchpad or Applications and sign out of Apple ID if transferring ownership; App Store maintains licensing.
Concept 4
Core 2 (220-1202) question cues
Identify which package type mounts as a volume (.dmg) versus which runs Installer (.pkg); Given a symptom isolated to one user, choose whether to inspect ~/Library or /Library first; Determine the correct uninstall approach for an App Store app vs a web-downloaded .app.
Example
Fixing a per-user preference issue: check ~/Library/Preferences before altering /Library.
Sample questions
Select an answer to reveal the explanation. For tracked practice and weak-area review, use the Cultiv8 app.
Q1.An A+ support scenario describes this situation: Installing an app downloaded as a .dmg: double-click .dmg, drag the .app to /Applications, eject the mounted image. Which answer fits best?
Q2.A support ticket includes this clue: Installing a .pkg: double-click runs Installer, follow prompts, may require administrator password. Which concept is being tested?
Q3.Read this A+ scenario: Removing an app installed from App Store: delete from Launchpad or Applications and sign out of Apple ID if transferring ownership; App Store maintains licensing. Which term or action matches it?
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