Note: the second command line is optional, it is used to download source packages.
Resynchronize your package index files:
$ sudo apt update
Packages installation
Install the binary packages; the "plugins" package is highly recommended but not mandatory, scripting API packages are optional (popular languages are python and perl).
deb [arch=amd64,i386 signed-by=/etc/apt/keyrings/weechat.asc] https://weechat.org/debian sid main deb-src [arch=amd64,i386 signed-by=/etc/apt/keyrings/weechat.asc] https://weechat.org/debian sid main
deb [arch=amd64,i386 signed-by=/etc/apt/keyrings/weechat.asc] https://weechat.org/debian trixie main deb-src [arch=amd64,i386 signed-by=/etc/apt/keyrings/weechat.asc] https://weechat.org/debian trixie main
deb [arch=amd64,i386,arm64,armhf signed-by=/etc/apt/keyrings/weechat.asc] https://weechat.org/debian bookworm main deb-src [arch=amd64,i386,arm64,armhf signed-by=/etc/apt/keyrings/weechat.asc] https://weechat.org/debian bookworm main
deb [arch=amd64,i386,arm64,armhf signed-by=/etc/apt/keyrings/weechat.asc] https://weechat.org/debian bullseye main deb-src [arch=amd64,i386,arm64,armhf signed-by=/etc/apt/keyrings/weechat.asc] https://weechat.org/debian bullseye main
deb [arch=amd64,i386 signed-by=/etc/apt/keyrings/weechat.asc] https://weechat.org/debian buster main deb-src [arch=amd64,i386 signed-by=/etc/apt/keyrings/weechat.asc] https://weechat.org/debian buster main
deb [arch=amd64,i386 signed-by=/etc/apt/keyrings/weechat.asc] https://weechat.org/debian stretch main deb-src [arch=amd64,i386 signed-by=/etc/apt/keyrings/weechat.asc] https://weechat.org/debian stretch main
deb [arch=amd64,i386 signed-by=/etc/apt/keyrings/weechat.asc] https://weechat.org/debian jessie main deb-src [arch=amd64,i386 signed-by=/etc/apt/keyrings/weechat.asc] https://weechat.org/debian jessie main
deb [arch=amd64,arm64 signed-by=/etc/apt/keyrings/weechat.asc] https://weechat.org/ubuntu plucky main deb-src [arch=amd64,arm64 signed-by=/etc/apt/keyrings/weechat.asc] https://weechat.org/ubuntu plucky main
deb [arch=amd64,arm64 signed-by=/etc/apt/keyrings/weechat.asc] https://weechat.org/ubuntu oracular main deb-src [arch=amd64,arm64 signed-by=/etc/apt/keyrings/weechat.asc] https://weechat.org/ubuntu oracular main
deb [arch=amd64,arm64 signed-by=/etc/apt/keyrings/weechat.asc] https://weechat.org/ubuntu noble main deb-src [arch=amd64,arm64 signed-by=/etc/apt/keyrings/weechat.asc] https://weechat.org/ubuntu noble main
deb [arch=amd64 signed-by=/etc/apt/keyrings/weechat.asc] https://weechat.org/ubuntu mantic main deb-src [arch=amd64 signed-by=/etc/apt/keyrings/weechat.asc] https://weechat.org/ubuntu mantic main
deb [arch=amd64 signed-by=/etc/apt/keyrings/weechat.asc] https://weechat.org/ubuntu lunar main deb-src [arch=amd64 signed-by=/etc/apt/keyrings/weechat.asc] https://weechat.org/ubuntu lunar main
deb [arch=amd64 signed-by=/etc/apt/keyrings/weechat.asc] https://weechat.org/ubuntu kinetic main deb-src [arch=amd64 signed-by=/etc/apt/keyrings/weechat.asc] https://weechat.org/ubuntu kinetic main
deb [arch=amd64 signed-by=/etc/apt/keyrings/weechat.asc] https://weechat.org/ubuntu jammy main deb-src [arch=amd64 signed-by=/etc/apt/keyrings/weechat.asc] https://weechat.org/ubuntu jammy main
deb [arch=amd64 signed-by=/etc/apt/keyrings/weechat.asc] https://weechat.org/ubuntu impish main deb-src [arch=amd64 signed-by=/etc/apt/keyrings/weechat.asc] https://weechat.org/ubuntu impish main
deb [arch=amd64 signed-by=/etc/apt/keyrings/weechat.asc] https://weechat.org/ubuntu hirsute main deb-src [arch=amd64 signed-by=/etc/apt/keyrings/weechat.asc] https://weechat.org/ubuntu hirsute main
deb [arch=amd64 signed-by=/etc/apt/keyrings/weechat.asc] https://weechat.org/ubuntu groovy main deb-src [arch=amd64 signed-by=/etc/apt/keyrings/weechat.asc] https://weechat.org/ubuntu groovy main
deb [arch=amd64 signed-by=/etc/apt/keyrings/weechat.asc] https://weechat.org/ubuntu focal main deb-src [arch=amd64 signed-by=/etc/apt/keyrings/weechat.asc] https://weechat.org/ubuntu focal main
deb [arch=amd64,i386 signed-by=/etc/apt/keyrings/weechat.asc] https://weechat.org/ubuntu eoan main deb-src [arch=amd64,i386 signed-by=/etc/apt/keyrings/weechat.asc] https://weechat.org/ubuntu eoan main
deb [arch=amd64,i386 signed-by=/etc/apt/keyrings/weechat.asc] https://weechat.org/ubuntu disco main deb-src [arch=amd64,i386 signed-by=/etc/apt/keyrings/weechat.asc] https://weechat.org/ubuntu disco main
deb [arch=amd64,i386 signed-by=/etc/apt/keyrings/weechat.asc] https://weechat.org/ubuntu cosmic main deb-src [arch=amd64,i386 signed-by=/etc/apt/keyrings/weechat.asc] https://weechat.org/ubuntu cosmic main
deb [arch=amd64,i386 signed-by=/etc/apt/keyrings/weechat.asc] https://weechat.org/ubuntu bionic main deb-src [arch=amd64,i386 signed-by=/etc/apt/keyrings/weechat.asc] https://weechat.org/ubuntu bionic main
deb [arch=amd64,i386 signed-by=/etc/apt/keyrings/weechat.asc] https://weechat.org/ubuntu artful main deb-src [arch=amd64,i386 signed-by=/etc/apt/keyrings/weechat.asc] https://weechat.org/ubuntu artful main
deb [arch=amd64,i386 signed-by=/etc/apt/keyrings/weechat.asc] https://weechat.org/ubuntu zesty main deb-src [arch=amd64,i386 signed-by=/etc/apt/keyrings/weechat.asc] https://weechat.org/ubuntu zesty main
deb [arch=amd64,i386 signed-by=/etc/apt/keyrings/weechat.asc] https://weechat.org/ubuntu yakkety main deb-src [arch=amd64,i386 signed-by=/etc/apt/keyrings/weechat.asc] https://weechat.org/ubuntu yakkety main
deb [arch=amd64,i386 signed-by=/etc/apt/keyrings/weechat.asc] https://weechat.org/ubuntu xenial main deb-src [arch=amd64,i386 signed-by=/etc/apt/keyrings/weechat.asc] https://weechat.org/ubuntu xenial main
deb [arch=amd64,i386 signed-by=/etc/apt/keyrings/weechat.asc] https://weechat.org/ubuntu wily main deb-src [arch=amd64,i386 signed-by=/etc/apt/keyrings/weechat.asc] https://weechat.org/ubuntu wily main
deb [arch=amd64,i386 signed-by=/etc/apt/keyrings/weechat.asc] https://weechat.org/ubuntu vivid main deb-src [arch=amd64,i386 signed-by=/etc/apt/keyrings/weechat.asc] https://weechat.org/ubuntu vivid main
deb [arch=amd64,i386 signed-by=/etc/apt/keyrings/weechat.asc] https://weechat.org/ubuntu utopic main deb-src [arch=amd64,i386 signed-by=/etc/apt/keyrings/weechat.asc] https://weechat.org/ubuntu utopic main
deb [arch=amd64,i386 signed-by=/etc/apt/keyrings/weechat.asc] https://weechat.org/ubuntu trusty main deb-src [arch=amd64,i386 signed-by=/etc/apt/keyrings/weechat.asc] https://weechat.org/ubuntu trusty main
deb [arch=amd64,i386 signed-by=/etc/apt/keyrings/weechat.asc] https://weechat.org/ubuntu precise main deb-src [arch=amd64,i386 signed-by=/etc/apt/keyrings/weechat.asc] https://weechat.org/ubuntu precise main
deb [arch=armhf,arm64 signed-by=/etc/apt/keyrings/weechat.asc] https://weechat.org/raspbian bookworm main deb-src [arch=armhf,arm64 signed-by=/etc/apt/keyrings/weechat.asc] https://weechat.org/raspbian bookworm main
deb [arch=armhf,arm64 signed-by=/etc/apt/keyrings/weechat.asc] https://weechat.org/raspbian bullseye main deb-src [arch=armhf,arm64 signed-by=/etc/apt/keyrings/weechat.asc] https://weechat.org/raspbian bullseye main
deb [arch=armhf signed-by=/etc/apt/keyrings/weechat.asc] https://weechat.org/raspbian buster main deb-src [arch=armhf signed-by=/etc/apt/keyrings/weechat.asc] https://weechat.org/raspbian buster main
deb [arch=armhf signed-by=/etc/apt/keyrings/weechat.asc] https://weechat.org/raspbian stretch main deb-src [arch=armhf signed-by=/etc/apt/keyrings/weechat.asc] https://weechat.org/raspbian stretch main
deb [arch=armhf signed-by=/etc/apt/keyrings/weechat.asc] https://weechat.org/raspbian jessie main deb-src [arch=armhf signed-by=/etc/apt/keyrings/weechat.asc] https://weechat.org/raspbian jessie main
deb [arch=armhf signed-by=/etc/apt/keyrings/weechat.asc] https://weechat.org/raspbian wheezy main deb-src [arch=armhf signed-by=/etc/apt/keyrings/weechat.asc] https://weechat.org/raspbian wheezy main