how to install llvmenv on ubuntu 22.04

2 min read 05-02-2025

LLVM is a powerful compiler infrastructure project. It's crucial for many development tasks, especially those involving languages like C++, Swift, and Rust. This guide details how to install LLVM on your Ubuntu 22.04 system using llvmenv, a convenient tool for managing multiple LLVM versions. This method offers flexibility and avoids conflicts with system-wide installations.

Why Use llvmenv?

Using a dedicated tool like llvmenv provides several advantages:

Multiple LLVM Versions: Manage different LLVM versions simultaneously without conflicts. This is essential for projects with specific version requirements.
Isolation: Keeps your LLVM installations isolated from the system's default version. This prevents unintended modifications or conflicts.
Clean Installation: llvmenv creates a clean, self-contained environment for each LLVM version.
Easy Switching: Switching between different LLVM versions is straightforward.

Prerequisites

Before installing llvmenv, ensure you have the necessary prerequisites:

Git: llvmenv is installed via Git. Install it if you don't already have it:
```
sudo apt update
sudo apt install git
```
Python 3: llvmenv uses Python 3. Verify it's installed:
```
python3 --version
```
If not, install it:
```
sudo apt install python3
```

Installing llvmenv

Now, let's install llvmenv:

Clone the repository:

git clone https://github.com/pyenv/llvmenv.git ~/.llvmenv

Add llvmenv to your shell's configuration: Add the following lines to your shell's configuration file (e.g., ~/.bashrc, ~/.zshrc). The exact path might vary depending on your shell:
```
export LLVMENV_ROOT="$HOME/.llvmenv"
export PATH="$LLVMENV_ROOT/bin:$PATH"
eval "$(llvmenv init -)"
```
Reload your shell configuration: Source the file to apply the changes:
```
source ~/.bashrc  # Or ~/.zshrc, depending on your shell
```
Verify the installation: Check if llvmenv is installed correctly:
```
llvmenv --version
```
You should see the llvmenv version number if the installation was successful.

Installing a Specific LLVM Version

After installing llvmenv, you can install any supported LLVM version. Let's install LLVM 16 as an example:

Install LLVM 16:
```
llvmenv install llvm@16
```
Set the LLVM version: Set the newly installed version as the global version:
```
llvmenv global llvm@16
```
Verify the installation: Check the currently active LLVM version:
```
llvmenv version
```
This should show llvm@16.

Using LLVM

Now you can use the installed LLVM version with your compiler tools. For example, if you are compiling C++ code, you can use clang++ (which is included in the LLVM package) to compile your code.

Managing Multiple LLVM Versions

llvmenv allows you to manage multiple LLVM versions. You can install additional versions using llvmenv install llvm@VERSION and switch between them using llvmenv global llvm@VERSION.

Uninstalling llvmenv and LLVM

To uninstall llvmenv and a specific LLVM version, you can simply delete the related directories. Remember to remove the llvmenv entries from your shell's configuration file as well.

This detailed guide should enable you to successfully install and manage various LLVM versions on your Ubuntu 22.04 system using llvmenv. Remember to consult the official llvmenv documentation for more advanced features and options.