rebase

Product	Command type
ClearCase®	cleartool subcommand

Platform
UNIX®
Linux®
Windows®

Description

The rebase command reconfigures a stream by adding, dropping, or replacing one or more of the stream's foundation baselines. The file and directory versions selected by those new baselines (and thus their associated activities) then become visible in the stream's views.

Only labeled baselines can serve as foundation baselines.

Any changes made in the stream before a rebase operation are preserved during the rebase. For any file modified in the stream, rebase merges any changes that are present in versions of that file in the new foundation baselines into the latest version of that file in the stream, thereby creating a new version. All such merged versions are captured in the change set of an integration activity that rebase creates. This integration activity becomes the view's current activity until the rebase operation is completed or canceled. No integration activity is created if there is nothing to merged; for example, when you rebase a newly created view, there is nothing to merge.

You must perform a rebase operation in a view belonging to the stream that is being rebased. Before starting the rebase operation, it is good practice to check in all files in that view. By default, the rebase operation stops when it encounters a checkout conflict. However, for a project or a stream enabled with the POLICY_REBASE_CO policy, and for single stream project, rebase skips the checked-out file and continue with other files.

If you want to recommend a baseline after rebasing to it, you must add it to the list of recommended baselines with chstream –recommended.

As a rule, you should rebase development streams often to pick up changes in the project's recommended baselines. By doing so, you can find integration problems early, when they are easier to fix. In addition, rebasing just before performing a deliver operation reduces or eliminates the need for manual merging during the delivery.

You cannot rebase when a deliver operation is in progress.

Rules for rebasing a stream

A stream can be rebased to a baseline that meets any of the following criteria:

The baseline is not from the stream that is being rebased.
The baseline is labeled. Baselines created by deliver operations are not labeled by default. For information about how to change a baseline's labeling status, see the chbl reference page.

Additional rules apply to integration streams and development streams in selecting a baseline:

An integration stream can be rebased only to a baseline created in another project or to an imported or initial baseline of that project.
A development stream can be rebased to a baseline that meets one of the following criteria:
- The baseline was created in its parent stream.
- The baseline is in its parent stream's foundation.
- The baseline is an ancestor of the development stream's parent foundation baseline and created on the same stream as the parent's foundation baseline.
- The baseline was created in a stream other than its parent stream and is contained in its parent stream. A baseline is contained in another baseline if all changes in the first baseline are included in the second baseline.
Note: Read-Only streams and nonmodifiable components in a development stream are exempt from the above rules. However, if the component's modifiability changes in the future, the development stream might not be able to modify the component at the baseline it is configured with. The development stream might be able to modify the component at the baseline it is configured with if the baseline is contained in its parent stream for this component. Otherwise, it may not until the baseline is rebased to a compatible baseline for that component.

Rebase is typically used to advance a stream's configuration, that is, to replace its current foundation baselines with more recent ones. However, under certain conditions, rebase can be used to revert a baseline, and to add or drop a component in a stream's configuration. It can also switch to a baseline that is neither an ancestor nor a descendant of the current foundation. The rules explained above are general rules for all rebase operations. You need to satisfy only the general rules when adding a component to a stream. When you advance, revert, drop, or switch a baseline, you need to satisfy the general rules and some additional ones.

To advance a stream's configuration, the new baseline must contain the current foundation baseline.
To revert or drop a baseline for a component in a stream, one of the following conditions must be met:
- The component is nonmodifiable.
- The component is modifiable but has not been modified in the stream, and the component is not in the configuration of any child streams.
To switch to a baseline that is neither an ancestor nor a descendant of the current foundation, one of the following conditions must be met:
- The component is nonmodifiable.
- The component is modifiable but has not been modified in the stream, and the component is not in the configuration of any child streams.
- The component has been modified but the new baseline contains the current foundation baseline, and the component is not in the configuration of any child streams.

These rules ensure that any changes made in a stream are not lost when the configuration changes.

Handling of elements of nondefault merge types

In a rebase operation, automatic merging is the default behavior for elements, unless user or never merge types were set for the elements. For information about setting merge behavior for an element type, see mkeltype.

Rebase and deliver operations handle elements of user or never merge types in much the same way. For more information, see this topic in the deliver reference page.

Restrictions

Identities

No special identity required.

Locks

An error occurs if one or more of these objects are locked: the project VOB, the development stream.

Mastership

(Replicated VOBs only) Your current replica must master the development stream.

Options and arguments

Invoking the graphical user interface

Default: Command-line interface.
–gr/aphical: Starts the graphical user interface for the rebase operation.

Specifying the rebase view

Default: If a stream is specified, the view attached to the stream (provided that only one view is attached to the stream; if multiple views are attached, a view must be specified.) If a stream is not specified, the current working UCM view.
–vie/w development-view_tag: Specifies the view in which to execute the rebase command. The view must be associated with a stream that is the stream to be rebased.
–reset –vie/w new-development-view_tag: Resets the target view to a new development view. Use this option should the target view become inaccessible.
–rmviewref: Removes references to the inaccessible view from every VOB in which the view is registered. This is equivalent to rmview –uuid. Errors result when you attempt to remove view references from VOBs that are inaccessible. However, if the command returns OK status, you can safely ignore such errors. Be cautious when using this option to avoid stranding checked out files.

Specifying the stream to be rebased

Default

If a view is specified, the stream attached to the view. If a view is not specified, the stream attached to the current UCM view.

–str/eam stream-selector

Specifies the stream to be rebased.

Specifying the stream alone is sufficient for canceling, previewing, resuming, completing, and checking status of a rebase operation. A view is not required. When beginning a new rebase operation, a view is required if it cannot be uniquely determined.

stream-selector is of the form [stream:]stream-name[@vob-selector], where vob-selector specifies the stream's project VOB.

Canceling a rebase operation

–can/cel: Cancels a rebase operation and restores the stream's previous configuration. The option deletes the integration activity and any versions created by the rebase operation that are not yet checked in.
If any new versions have been checked in, the cancellation process is halted, and you are informed of completed merges and any checked in versions that resulted from the rebase activity. After undoing the merges and checkins, you must issue the rebase –cancel command again to cancel the rebase operation.

Obtaining the status of a rebase operation

–sta/tus: Displays the status of a rebase operation. You are informed whether a rebase operation is in progress in the specified stream; and if so, this option displays the new foundation baselines and the list of new activities being brought into the stream.

Previewing the results of a rebase operation

–pre/view: Shows which baselines would change and which new activities would be brought into the stream if a rebase operation were to be executed. –preview fails if a rebase operation is in progress.

Controlling output verbosity

Default: Varies according to the kind of output that the options described here modify. See the descriptions of –status and –preview.
–l/ong: As a modifier of –status, displays a list of activities and change sets and a list of elements that will require merging, in addition to the default information displayed by –status.
As a modifier of –preview, displays a list of versions that potentially require merging, in addition to the default information displayed by –preview.
–s/hort: Modifies the –preview option. Displays only a list of the activities.

Specifying baselines

Default

None.

–rec/ommended

Specifies that a development stream is to be rebased to its parent stream's recommended baselines. Using this option clears the existing foundation baselines and replaces them with the recommended ones.

–bas/eline baseline-selector[,...]

Specifies one or more baselines to use as new foundation baselines for the stream. See Rules for rebasing a stream for criteria for specifying baselines. Using this option replaces only the baselines in the components for which newer baselines are explicitly specified.

baseline-selector is of the form [baseline:]baseline-name[@vob-selector], where vob-selector specifies the baseline's project VOB.

If you rebase to a composite baseline, you need not specify multiple baselines separately. Any additions to the composite baseline dependencies are propagated through subsequent rebase operations.

Note: Depending on whether –recommended or –baseline is used, the result of rebasing to a composite baseline may be different. For example, the foundation baseline for a development stream is composite baseline X1, which selects member baselines A1, B1 and C1. New baselines A2 and A3 are created in the parent stream and picked up by the development stream through rebase operations. Now the foundation baselines for the development stream are X1 and A3. (A3 now overrides the A1 that is a member of composite baseline X1.) Then, in the parent stream, a new composite baseline, X2, is made and recommended. This baseline selects A2, B2, and C2. Now, when you rebase –recommended, A3 is removed from the foundation of the development stream. The new foundation baselines for the development stream are X2 and its members. However, if you rebase to X2 using the –baseline option, A3 is not removed from the foundation, and the new foundation baselines for the development stream are X2 and A3.

–dba/seline baseline-selector[,...]: Specifies one or more baselines to remove from the stream's configuration. Files in those baseline's components are subsequently no longer visible or modifiable in the stream. See Rules for rebasing a stream for criteria for specifying baselines.
baseline-selector is of the form [baseline:]baseline-name[@vob-selector], where vob-selector specifies the baseline's project VOB.

Resuming a rebase operation

Default: None.
–res/ume: Restarts a rebase operation from the point at which it has been suspended. A rebase operation can be interrupted (as with CTRL+C) or when it encounters an external error or condition that requires more information. To continue the operation, reissue the rebase command with the –resume option. However, you cannot resume a rebase operation that has been successfully halted with the –cancel option.

Completing a rebase operation

Default: None.
–com/plete: Completes a rebase operation. Checking in merged versions in the development view does not complete the rebase operation; you must use –complete to complete a rebase operation. You can use this option after a rebase has been suspended, for example, to resolve file conflicts. It resumes the rebase operation, verifies that needed merges were made, checks in any versions that are checked out, and records changes in the change set for the rebase activity.

Merge options

Default: Works as automatically as possible, prompting you to make a choice in cases where two or more contributors differ from the base contributor. For general information, see the findmerge reference page.
-ok: Pauses for verification on each element to be merged, allowing you to process some elements and skip others. This option does not remain in effect after a rebase operation is interrupted.
–gm /erge: Performs a graphical merge for each element that requires it. This option does not remain in effect after a rebase operation is interrupted.
–q/uery: Prompts you for confirmation before proceeding with each change in the from-versions. Changes in the to-version are automatically accepted unless a conflict exists. This option does not remain in effect after a rebase operation is interrupted.
–abo/rt: Cancels a merge if it is not completely automatic. This option does not remain in effect after a rebase operation is interrupted.
–qal/l: Turns off all automated merging. Prompts you to specify whether to proceed with each change. This option does not remain in effect after a rebase operation is interrupted.
–qnt/rivial: Turns off automated merging and prompts you to determine whether you want to proceed except in the case where a trivial merge would be done. This option does not remain in effect after a rebase operation is interrupted.
–ser/ial: Reports differences with each line containing output from one contributor, instead of in a side-by-side format. This option does not remain in effect after a rebase operation is interrupted.

Controlling command-line prompts

Default: Prompt for user input.
–f/orce: Suppresses prompting for user input during the course of a rebase operation. The –force option does not remain in effect if the rebase is interrupted; you must respecify it when you restart the rebase operation with –resume or –complete. The merge options to the rebase command are not affected by the –force option.

Examples

The UNIX system and Linux examples in this section are written for use in csh. If you use another shell, you may need to use different quoting and escaping conventions.

The Windows examples that include wildcards or quoting are written for use in cleartool interactive mode. If you use cleartool single-command mode, you may need to change the wildcards and quoting to make your command interpreter process the command appropriately.

In cleartool single-command mode, cmd-context represents the UNIX system and Linux shells or Windows command interpreter prompt, followed by the cleartool command. In cleartool interactive mode, cmd-context represents the interactive cleartool prompt.

Start a rebase operation.
cmd-context rebase –recommended
Advancing to baseline "BL1.119" of component "webo_modeler" Updating rebase view's config spec... Creating integration activity... Setting integration activity... Merging files... No versions require merging in stream "chris_webo_dev". Build and test are necessary to ensure that the merges were completed correctly. When build and test are confirmed, run "cleartool rebase -complete".
Complete a rebase operation.
cmd-context rebase –completeRebase in progress on stream "chris_webo_dev". Started by "ktessier" at 06/06/00 15:36:42. Merging files... No versions require merging in stream "chris_webo_dev". Checking in files... Clearing integration activity... Updating stream's configuration... Cleaning up... Rebase completed.