at software package provides Delayed job execution and batch processing, you can install in your Debian 9 (Stretch) by running the commands given below on the terminal,
$ sudo apt-get update $ sudo apt-get install at
at is installed in your system.
Make ensure the at package were installed using the commands given below,
$ sudo dpkg-query -l | grep at *
You will get with at package name, version, architecture and description in a table
| Distro | Debian 9 stretch |
| Section | Administration Utilities |
| Package | at |
| Version | 3.1.16-1 |
| Description | Delayed job execution and batch processing |
| Sub Section | admin |