terminal - Where can I find documentation for shell commands?

Closed. This question is off-topic. It is not currently accepting answers.

Closed 12 months ago.

Locked. This question and its answers are locked because the question is off-topic but has historical significance. It is not currently accepting new answers or interactions.

For using a shell commands through a terminal program, where can I find documentation or help or man pages for the commands as implemented in Android?

While it would be nice to have them on the device via man, PDF or web-based would be fine, too.

When I run "man" from terminal, I get an error and I haven't found a good source online.