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If you’ve ever worked with IBM DevOps Code ClearCase (formerly IBM Rational ClearCase) in a multi-branch development environment, you might have encountered the dreaded evil twin. The "evil twin" occurs when two independent branches have the same file or directory name of a ClearCase VOB. Therefore, when the files or directories are merged, it leads to merger conflicts.
We know several admins have experienced this evil twin issue in ClearCase. What did your team do to implement a trigger or policy to prevent them?
Share your experience — we’d love to hear how this classic ClearCase challenge has been tackled.
#IBMChampion
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It has always been solved here:
https://abs-consulting.com/_faq/clearcase_triggers.php?inhibit_duplicate_ele_pl
The user is warned BEFORE the evil twin is created when a new element is the movement of an existing element would create an evil twin. The solution is free and the source code is provided. This solution works for ClearCase 2.x and higher.
This is also handled in the ClearTrigger ClearCase add-on product. This solution also allows for the user to alternatively create a proper symbolic link to the existing element. You just need to turn on functionality bit #2. You can read about that bit here:
https://abs-consulting.com/products_cd/cleartrigger_distribution/dilbert/cleartrigger/help/key_functionality_bit2.shtml
or read about ClearTrigger in general or view a short movie about ClearTrigger here:
https://abs-consulting.com/_products/products_cleartrigger.php?details
Hope this helps.
This technote explains how to fix it:https://www.ibm.com/support/pages/about-evil-twins
There's also documentation on how to prevent it:https://www.ibm.com/docs/en/clearcase/11.0.0?topic=administration-managing-evil-twins
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Lettie Ar-Rahmaan
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