yq/pkg/yqlib/doc/headers/Multiply.md

Like the multiple operator in jq, depending on the operands, this multiply operator will do different things. Currently only objects are supported, which have the effect of merging the RHS into the LHS.

Upcoming versions of yq will add support for other types of multiplication (numbers, strings).

To concatenate when merging objects, use the *+ form (see examples below). This will recursively merge objects, appending arrays when it encounters them.

Note that when merging objects, this operator returns the merged object (not the parent). This will be clearer in the examples below.

Merging files

Note the use of eval-all to ensure all documents are loaded into memory.

yq eval-all 'select(fileIndex == 0) * select(fileIndex == 1)' file1.yaml file2.yaml