Install ckmux

Download packages from the latest release. Choose the operating system and architecture of the machine that will run ckmux. In filenames below, VERSION means the release number shown on that page.

Linux packages require a compatible modern system runtime; they are not universal static binaries. Ubuntu 20.04 is unsupported. For Linux ARM64, Intel Macs, or another system without a matching binary, see Building from source; no matching prebuilt archive is published. Windows packages are checked on Windows 11 ARM64 and Windows Server x64; manual Windows Terminal and installer acceptance remains pending.

macOS

With Homebrew:

brew install cklukas/ckmux/ckmux
ckmux --version
ckmux

The prebuilt Apple Silicon archive and source builds using Apple's system C++ library require macOS 26 or newer. For installation without Homebrew, use the archive instructions. Older macOS versions would need a separately verified alternative standard library; see the build requirements.

Linux

Download only the package you intend to install into a fresh directory, then run the appropriate command there.

Debian and Ubuntu

sudo apt install ./ckmux_*_amd64.deb
ckmux --version
ckmux

APT resolves the package's runtime dependencies. If the distribution cannot satisfy them, use a supported newer system or build from source.

Fedora and other RPM distributions

sudo dnf install ./ckmux-*.x86_64.rpm
ckmux --version
ckmux

The RPM is built on the same Ubuntu baseline as the other Linux binaries. Its format alone does not establish compatibility with every Fedora or RHEL release; DNF must be able to resolve its runtime dependencies.

Windows

Use Windows Terminal. Choose arm64 for Windows on ARM, or x64 for Intel/AMD Windows. WSL is separate: install the Linux package inside WSL if that is where you want your sessions to run.

Per-user MSI

1. Download and open the matching .msi from the release page.
2. Install for your current user. Administrator access is not required.
3. Open PowerShell in Windows Terminal and launch the installed executable.

The installer places ckmux under your LocalAppData folder unless you select another destination. Note the installation folder shown in the installer. In PowerShell, change to that folder (the one containing bin) and run:

.\bin\ckmux.exe --version
.\bin\ckmux.exe

The MSI does not add ckmux to the global PATH. Optionally add that installation's bin folder to your user PATH and open a new terminal to use ckmux by name.

Portable ZIP

Extract the matching ZIP to a folder you control. Open PowerShell in the extracted package directory that contains bin, then run:

.\bin\ckmux.exe --version
.\bin\ckmux.exe

Keep the entire package together, including the ConPTY DLL, architecture subdirectories, runtime identity record, and license notice. Copying only ckmux.exe does not preserve the packaged runtime.

The default shell is cmd.exe. To choose PowerShell, set an explicit shell path in configuration. See Native Windows for runtime details and build/test instructions.

macOS and Linux archives

Download the archive for your platform and its .sha256 sidecar. Use a user-owned installation prefix so no administrator access is needed. The example below uses Linux; on macOS choose Darwin-arm64 instead:

archive=ckmux-VERSION-Linux-x86_64.tar.gz
mkdir -p "$HOME/.local/opt"
tar -xzf "$archive" -C "$HOME/.local/opt"

The archive contains a top-level directory matching its filename without .tar.gz. Keep its bin/ and share/ directories together, then add that installation's bin directory to PATH:

export PATH="$HOME/.local/opt/ckmux-VERSION-Linux-x86_64/bin:$PATH"
ckmux --version
ckmux

To keep this setting, add the export line to your shell's startup file with the actual version/platform. The manual is in share/man/man1/ckmux.1 and the Markdown guide in share/doc/ckmux/ under that same installation directory.

Verify a download

Binary packages and archives have SHA-256 sidecars. Run these commands in the directory holding the downloaded file and its matching .sha256 file, substituting the exact filename:

# Linux
sha256sum -c ckmux-VERSION-Linux-x86_64.tar.gz.sha256
# macOS
shasum -a 256 -c ckmux-VERSION-Darwin-arm64.tar.gz.sha256

In PowerShell:

$file = 'ckmux-VERSION-Windows-arm64.zip'
$expected = ((Get-Content "$file.sha256" -Raw).Trim() -split '\s+')[0]
if ((Get-FileHash $file -Algorithm SHA256).Hash -ine $expected) {
    throw 'Checksum mismatch'
}

Upgrade or remove

Before upgrading, finish or save work in your running sessions. Stop the old server with ckmux kill-server only when you are ready to end all its programs. Client and server build identities must match; replacing the client does not upgrade an already-running server.

Windows uninstall preserves configuration and durable logs. Configuration locations on every platform are listed in Configuration.

If something does not work

• Command not found: check PATH, or run the executable by its full path.
• Client/server version mismatch: use the matching client to save work and stop the old server, then start the newly installed version.
• No Sixel images: the outer terminal must support Sixel; text remains usable without it. On Windows, keep all packaged runtime files together.
• Windows cannot start a detached server: some parent process jobs forbid independent child processes. Start from a normal Windows Terminal session; see Native Windows.

Continue with your first session.