実用性はないといえばないかもしれないが……

環境：

• Ubuntu 16.04

apt-getで一発インストール。

$ sudo apt-get install sl
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following NEW packages will be installed:
  sl
0 upgraded, 1 newly installed, 0 to remove and 110 not upgraded.
Need to get 24.4 kB of archives.
After this operation, 86.0 kB of additional disk space will be used.
Get:1 http://archive.ubuntu.com/ubuntu xenial/universe amd64 sl amd64 3.03-17build1 [24.4 kB]
Fetched 24.4 kB in 1s (17.1 kB/s)
Selecting previously unselected package sl.
(Reading database ... 63096 files and directories currently installed.)
Preparing to unpack .../sl_3.03-17build1_amd64.deb ...
Unpacking sl (3.03-17build1) ...
Processing triggers for man-db (2.7.5-1) ...
Setting up sl (3.03-17build1) ...

で、ソースはGithubで管理しているんですね。
mtoyoda/sl