jiri is a multi-purpose command-line tool originally designed to aid Vanadium development. The jiri tool has since been extracted from Vanadium and is now used by various multi-repository projects.
jiri is open source and is available here: https://github.com/vanadium/go.jiri
The “fetch repositories” step of Vanadium installation installs the jiri tool in $JIRI_ROOT/devtools/bin.
Run jiri help to learn more about the tool. (Note, this command assumes your PATH contains $JIRI_ROOT/devtools/bin.)