acl software package provides Access control list utilities, 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 acl
acl is installed in your system.
Make ensure the acl package were installed using the commands given below,
$ sudo dpkg-query -l | grep acl *
You will get with acl package name, version, architecture and description in a table
| Distro | Debian 9 stretch |
| Section | Utilities |
| Package | acl |
| Version | 2.2.52-3 |
| Description | Access control list utilities |
| Sub Section | Utils |