Pipelines - documentation for use of regular expressions in variables is very brief
Problem to solve
Pattern matching with variables is documented with just the following line
It is possible perform pattern matching against a variable and regular expression.
Complicated by the fact that - at present - only a subset of regular expressions work (bug: #35438 (closed)) customers trying to use this feature can spend a lot of effort trying to find complex ways to insert regular expressions into variables and to then use them, and in actual fact, regular expressions such as .* just don't work.
Customer ticket (internal)
Further details
Customer's example was setting regular expressions in variables globally in the CI yaml, allowing multiple jobs to be switched on and off with the same regular expression.
Setting variables in the GUI could also be a way to use this feature.