tee
TextPackage: coreutils
Writes what it receives both to a file and to standard output. sudo tee is how you write a root-owned file from a pipe, where sudo echo > file fails.
What its options do in the lessons
From the same glossary the lessons render under their commands, so the two cannot disagree.
tee -a- Appends to the file instead of truncating it —
tee’s equivalent of>>.