pub get

Get is one of the commands of the pub tool. Learn more about pub.

$ pub get [--offline]

This command gets all the dependencies listed in the pubspec.yaml file in the current working directory, as well as their transitive dependencies. For example:

$ pub get
Got dependencies!

If the system cache doesn’t already contain the dependencies, pub get updates the cache, downloading dependencies if necessary. To map packages back to the system cache, this command creates one or more packages directories and, as of Dart 1.12, a .packages file.

Once the dependencies are acquired, they may be referenced in Dart code. For example, if a package depends on test:

import "package:test/test.dart;

When pub get gets new dependencies, it writes a lockfile to ensure that future gets will use the same versions of those dependencies. Application packages should check in the lockfile to source control; this ensures the application will use the exact same versions of all dependencies for all developers and when deployed to production. Library packages should not check in the lockfile, though, since they’re expected to work with a range of dependency versions.

If a lockfile already exists, pub get uses the versions of dependencies locked in it if possible. If a dependency isn’t locked, pub gets the latest version of that dependency that satisfies all the version constraints. This is the primary difference between pub get and pub upgrade, which always tries to get the latest versions of all dependencies.

Getting a new dependency

If a dependency is added to the pubspec and then pub get is run, it gets the new dependency and any of its transitive dependencies and updates the links in the packages directory, and the mapping in the .packages file. However, it won’t change the versions of any already-acquired dependencies unless that’s necessary to get the new dependency.

Removing a dependency

If a dependency is removed from the pubspec and then pub get is run, it removes the dependency from the packages directory, and the .packages file, thus making it unavailable for importing. Any transitive dependencies of the removed dependency are also removed, as long as no remaining immediate dependencies also depend on them. Removing a dependency never changes the versions of any already-acquired dependencies.

The system package cache

Dependencies downloaded over the internet, such as those from Git and pub.dartlang.org, are stored in a system-wide cache. This means that if multiple packages use the same version of the same dependency, it only needs to be downloaded and stored locally once. It also means that it’s safe to delete the packages directories, or the .packages file, without worrying about re-downloading packages.

By default, the system package cache is located in the .pub-cache subdirectory of your home directory (on Mac and Linux), or in AppData\Roaming\Pub\Cache (on Windows). However, it may be configured by setting the PUB_CACHE environment variable before running pub.

Getting while offline

If you don’t have network access, you can still run pub get. Since pub downloads packages to a central cache shared by all packages on your system, it can often find previous-downloaded packages there without needing to hit the network.

However, by default, pub always tries to go online when you get if you have any hosted dependencies so that it can see if newer versions of them are available. If you don’t want it to do that, pass the --offline flag when running pub. In this mode, it only looks in your local package cache and tries to find a set of versions that work with your package from what’s already available.

Keep in mind that pub generates a lockfile after it does this. If the only version of some dependency in your cache happens to be old, this locks your app to that version. The next time you are online, you will likely want to run pub upgrade to upgrade to a later version.

Options

For options that apply to all pub commands, see Global options.