Learn Linux Shell Scripting - Fundamentals of Bash 4.4

at output

As you might have noticed, up until now we've only used commands that did not rely on stdout (a little sneaky, we know). However, once you think about it, this poses a real problem. Normally, when we deal with commands and scripts, we use stdout/stderr to get a feeling about the result of our actions. The same goes for interactive prompts: we use our keyboards to supply input via stdin. Now that we're scheduling non-interactive jobs, things will be different. For starters, we cannot use interactive constructs such as read anymore. Scripts will simply fail because there is no stdin available. But, again, there is no stdout available either, so we do not even see the scripts fail! Or is there?

Somewhere in the manpage of at, you can ...