flex-old software package provides Old version of the fast lexical analyzer generator, you can install in your Ubuntu 16.10 (Yakkety Yak) by running the commands given below on the terminal,
$ sudo apt-get update $ sudo apt-get install flex-old
flex-old is installed in your system.
Make ensure the flex-old package were installed using the commands given below,
$ sudo dpkg-query -l | grep flex-old *
You will get with flex-old package name, version, architecture and description in a table
| Distro | Ubuntu 16 10 yakkety yak |
| Section | Development |
| Package | flex-old |
| Version | 2.5.4a-10ubuntu1 |
| Description | Old version of the fast lexical analyzer generator |
| Sub Section | Devel |