Installation in Linux

@next_tutorial{tutorial_linux_gcc_cmake}


Original author	Ana Huamán
Compatibility	OpenCV >= 3.0

@tableofcontents

Quick start

Build core modules

@snippet linux_quick_install.sh body

Build with opencv_contrib

@snippet linux_quick_install_contrib.sh body

Detailed process

This section provides more details of the build process and describes alternative methods and tools. Please refer to the @ref tutorial_general_install tutorial for general installation details and to the @ref tutorial_config_reference for configuration options documentation.

Install compiler and build tools

To compile OpenCV you will need a C++ compiler. Usually it is G++/GCC or Clang/LLVM:
- Install GCC... @snippet linux_install_a.sh gcc
- ... or Clang: @snippet linux_install_b.sh clang
OpenCV uses CMake build configuration tool: @snippet linux_install_a.sh cmake
CMake can generate scripts for different build systems, e.g. make, ninja:
- Install Make... @snippet linux_install_a.sh make
- ... or Ninja: @snippet linux_install_b.sh ninja
Install tool for getting and unpacking sources:
- wget and unzip... @snippet linux_install_a.sh wget
- ... or git: @snippet linux_install_b.sh git

Download sources

There are two methods of getting OpenCV sources:

Download snapshot of repository using web browser or any download tool (~80-90Mb) and unpack it... @snippet linux_install_a.sh download
... or clone repository to local machine using git to get full change history (>470Mb): @snippet linux_install_b.sh download

@note Snapshots of other branches, releases or commits can be found on the GitHub and the official download page.

Configure and build

Create build directory: @snippet linux_install_a.sh prepare
Configure - generate build scripts for the preferred build system:
- For make... @snippet linux_install_a.sh configure
- ... or for ninja: @snippet linux_install_b.sh configure
Build - run actual compilation process:
- Using make... @snippet linux_install_a.sh build
- ... or ninja: @snippet linux_install_b.sh build

@note Configure process can download some files from the internet to satisfy library dependencies, connection failures can cause some of modules or functionalities to be turned off or behave differently. Refer to the @ref tutorial_general_install and @ref tutorial_config_reference tutorials for details and full configuration options reference.

@note If you experience problems with the build process, try to clean or recreate the build directory. Changes in the configuration like disabling a dependency, modifying build scripts or switching sources to another branch are not handled very well and can result in broken workspace.

@note Make can run multiple compilation processes in parallel, -j<NUM> option means "run jobs simultaneously". Ninja will automatically detect number of available processor cores and does not need -j option.

Check build results

After successful build you will find libraries in the build/lib directory and executables (test, samples, apps) in the build/bin directory: @snippet linux_install_a.sh check

CMake package files will be located in the build root: @snippet linux_install_a.sh check cmake

Install

@warning The installation process only copies files to predefined locations and does minor patching. Installing using this method does not integrate opencv into the system package registry and thus, for example, opencv can not be uninstalled automatically. We do not recommend system-wide installation to regular users due to possible conflicts with system packages.

By default OpenCV will be installed to the /usr/local directory, all files will be copied to following locations:

/usr/local/bin - executable files
/usr/local/lib - libraries (.so)
/usr/local/cmake/opencv5 - cmake package
/usr/local/include/opencv5 - headers
/usr/local/share/opencv5 - other files (e.g. trained cascades in XML format)

Since /usr/local is owned by the root user, the installation should be performed with elevated privileges (sudo): @snippet linux_install_a.sh install or @snippet linux_install_b.sh install

Installation root directory can be changed with CMAKE_INSTALL_PREFIX configuration parameter, e.g. -DCMAKE_INSTALL_PREFIX=$HOME/.local to install to current user's local directory. Installation layout can be changed with OPENCV_*_INSTALL_PATH parameters. See @ref tutorial_config_reference for details.

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