Download latest release from GitHub, extract archive and install an executable for your operating system.
Alternatively if you have Go compiler installed you may want to run:
go get kkn.fi/cmd/gist
% gist -h
usage: gist [-v] [-d string] [-p] [-a] file ... | -f file
-a create anonymous Gist
-d string
description for Gist
-f string
file name of the Gist. Reads file contents from stdin
-p create a public Gist
-token file
read GitHub personal access token from file (default $HOME/.github-gist-token)
-v print version and exit
BSD-3-Clause. See LICENSE for details.