How to download and install cmake (latest version) in ubuntu

1>Download cmake form https://cmake.org/download/

Download the (for example) this .sh file

Linux x86_64	cmake-4.4.2-linux-x86_64.sh
	cmake-4.4.2-linux-x86_64.tar.gz
Linux aarch64	cmake-4.4.2-linux-aarch64.sh
	cmake-4.4.2-linux-aarch64.tar.gz

Based on you PC 

2> make that file executable using 

chmod +x <your cmake downloaded file>

3> Run command (for example)

sudo ./cmake-4.4.2-linux-x86_64.sh --prefix=/usr/local

How to install libwebsocket form git? (discussion with gemenie)

Installing libwebsockets (LWS) directly from GitHub uses standard CMake.

Step-by-Step Installation (Linux / macOS)

1. Install System Dependencies

LWS requires cmake, gcc/g++ (or clang), and SSL headers (OpenSSL/WolfSSL).

• Ubuntu / Debian:
  
  
  Bash

  sudo apt update
  sudo apt install -y git cmake build-essential libssl-dev zlib1g-dev
  

• Fedora / RHEL / CentOS:
  
  
  Bash

  sudo dnf install -y git cmake gcc gcc-c++ openssl-devel zlib-devel
  

• macOS (Homebrew):
  
  
  Bash

  brew install git cmake openssl zlib
  

2. Clone the Official Repository

Clone the repository and check out a stable release tag (recommended over main for production reliability):

Bash

# Clone the repository
git clone https://github.com/warmcat/libwebsockets.git
cd libwebsockets

# (Optional) Checkout a stable release tag
git checkout v4.3-stable

3. Build and Install via CMake

LWS requires an out-of-source build directory:

Bash

# Create and enter build directory
mkdir build && cd build

# Configure build files
cmake .. \
  -DCMAKE_BUILD_TYPE=Release \
  -DCMAKE_INSTALL_PREFIX=/usr/local \
  -DLWS_WITH_SSL=ON \
  -DLWS_WITH_HTTP2=ON

# Compile using all CPU cores
make -j$(nproc)

# Install system-wide
sudo make install

# Refresh shared library link cache (Linux)
sudo ldconfig

Key CMake Options (Customizing Your Build)

You can pass extra flags to cmake .. depending on your requirements:

Flag	Default	Description
-DLWS_WITH_SSL=ON	ON	Enables OpenSSL/TLS support.
-DLWS_WITH_HTTP2=ON	ON	Enables HTTP/2 protocol support.
-DLWS_WITH_MINIMAL_EXAMPLES=ON	OFF	Builds sample client/server code in the build folder.
-DLWS_MAX_SMP=8	1 / Auto	Sets maximum SMP thread count for multi-threaded service loops.
-DCMAKE_INSTALL_PREFIX=/usr	/usr/local	Changes the default installation target directory.

Verifying the Installation

To verify your installation, create a minimal C test file (test.c):

C

#include <libwebsockets.h>
#include <stdio.h>

int main() {
    printf("LWS Version: %s\n", lws_get_library_version());
    return 0;
}

Compile and run it:

Bash

gcc test.c -o test -lwebsockets
./test