Install snapd

Arch

sudo pacman -S snapd

# enable the snapd systemd service:
sudo systemctl enable --now snapd.socket

Debian

# On Sid:
sudo apt install snapd

Fedora

sudo dnf copr enable zyga/snapcore
sudo dnf install snapd

# enable the snapd systemd service:
sudo systemctl enable --now snapd.service

# SELinux support is in beta, so currently:
sudo setenforce 0

# to persist, edit /etc/selinux/config
to set SELINUX=permissive and reboot.

Gentoo

Install the gentoo-snappy overlay.

OpenEmbedded/Yocto

Install the snap meta layer.

openSUSE

sudo zypper addrepo http://download.opensuse.org/repositories/system:/snappy/openSUSE_Leap_42.2/ snappy
sudo zypper install snapd

OpenWrt

Enable the snap-openwrt feed.

Ubuntu

sudo apt install snapd