env
ShellPackage: coreutils
Prints the environment, or runs a command in a modified one. On a script's first line, #!/usr/bin/env bash finds bash wherever it is installed.
What its options do in the lessons
From the same glossary the lessons render under their commands, so the two cannot disagree.
env -i- Starts with an empty environment. This is how you reproduce the bare environment cron runs a job in.