Command: Update

$ pub update [PACKAGE]

Without any additional arguments, pub update installs the latest versions of all the dependencies listed in the pubspec.yaml file in the current working directory, as well as their transitive dependencies, to the packages directory located next to the pubspec. For example:

$ pub update
Dependencies updated!

When pub update updates dependency versions, it writes a lockfile to ensure that future pub installs 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 update will ignore it and generate a new one from scratch using the latest versions of all dependencies. This is the primary difference between pub update and pub install, which always tries to install the dependency versions specified in the existing lockfile.

Updating specific dependencies

It’s possible to tell pub update to update specific dependencies to the latest version while leaving the rest of the dependencies alone as much as possible. For example:

$ pub update unittest args
Dependencies updated!

Updating a dependency updates its transitive dependencies to their latest versions as well. Usually, no other dependencies are updated; they stay at the versions that are locked in the lockfile. However, if the requested updates cause incompatibilities with these locked versions, they will be selectively unlocked until a compatible set of versions is found.

Installing a new dependency

If a dependency is added to the pubspec before pub update is run, it will install the new dependency and any of its transitive dependencies to the packages directory. This is the same behavior as pub install.

Uninstalling a dependency

If a dependency is removed from the pubspec before pub update is run, it will remove the dependency from the packages directory, thus making it unavailable for importing. Any transitive dependencies of the removed dependency will also be removed, as long as no remaining immediate dependencies also depend on them. This is the same behavior as pub install.