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How To Set Default GCC and G++ Version in Ubuntu?

Ubuntu 10

In this article, we will explore how to set the default GCC and G++ version in Ubuntu. This is a common requirement for developers who need to work with different versions of GCC and G++ for various projects. Before we get started, it’s important to note that changing the default version of GCC and G++ can have implications for compatibility and dependencies. Therefore, ensure to test your code and verify that it works correctly with the chosen version before making it the default.

Quick Answer

To set the default GCC and G++ version in Ubuntu, you can either manually create symbolic links or use the update-alternatives command. Manually creating symbolic links involves removing existing links and creating new ones for the desired version. The update-alternatives command allows you to set alternatives and choose the default version interactively.

What is GCC and G++?

GCC stands for GNU Compiler Collection, a standard compiler for most UNIX-like operating systems, including Ubuntu. G++ is a part of GCC that supports the C++ language.

Installing Desired Versions of GCC and G++

Before setting a version as the default, you need to install it. For instance, to install GCC and G++ version 4.4, you would use the following command:

sudo apt-get install gcc-4.4 g++-4.4

In this command, sudo allows you to run commands with administrative privileges, apt-get is the package handling utility in Ubuntu, and install is the command to install new packages.

Setting the Default Version

There are two main methods to set the default version of GCC and G++ in Ubuntu: manually creating symbolic links or using the update-alternatives command.

Method 1: Manually Creating Symbolic Links

First, remove the existing symbolic links for GCC and G++:

sudo rm /usr/bin/gcc
sudo rm /usr/bin/g++

Then, create new symbolic links for your desired version. For example, to set GCC and G++ to version 4.4, use the following commands:

sudo ln -s /usr/bin/gcc-4.4 /usr/bin/gcc
sudo ln -s /usr/bin/g++-4.4 /usr/bin/g++

In these commands, ln -s creates a symbolic link, /usr/bin/gcc-4.4 is the source file, and /usr/bin/gcc is the link name.

Finally, verify that the new version is set as the default:

gcc --version
g++ --version

Method 2: Using the update-alternatives Command

Firstly, use the --install option to set the alternatives:

sudo update-alternatives --install /usr/bin/gcc gcc /usr/bin/gcc-4.4 10
sudo update-alternatives --install /usr/bin/g++ g++ /usr/bin/g++-4.4 10

In these commands, --install is the command to add alternatives, /usr/bin/gcc is the master link, gcc is the link group, /usr/bin/gcc-4.4 is the slave link, and 10 is the priority of the alternative.

Next, use the --config option to select the default version interactively:

sudo update-alternatives --config gcc
sudo update-alternatives --config g++

This will present a list of installed GCC and G++ versions, allowing you to choose the default version.

Conclusion

In this article, we have provided a detailed guide on how to set the default GCC and G++ version in Ubuntu. Whether you prefer manually creating symbolic links or using the update-alternatives command, this guide should help you achieve your goal. Remember to always test your code with the new version before making it the default to avoid any compatibility issues.

Can I have multiple versions of GCC and G++ installed on Ubuntu?

Yes, you can have multiple versions of GCC and G++ installed on Ubuntu. Each version is installed as a separate package and can be selected as the default version using the methods mentioned in the article.

How do I check the currently installed versions of GCC and G++ on my Ubuntu system?

You can check the currently installed versions of GCC and G++ by running the following commands in the terminal:

gcc --version
g++ --version

These commands will display the version numbers of GCC and G++ respectively.

Can I switch between different versions of GCC and G++ easily?

Yes, you can switch between different versions of GCC and G++ easily by following the methods mentioned in the article. Simply change the symbolic links or use the update-alternatives command to select the desired version as the default.

Will changing the default version of GCC and G++ affect my existing projects?

Yes, changing the default version of GCC and G++ can potentially affect your existing projects. Different versions may have different language features, compatibility with libraries, and optimizations. It is important to thoroughly test your code with the new version before making it the default, to ensure compatibility and functionality.

How can I revert back to the original/default version of GCC and G++?

To revert back to the original/default version of GCC and G++, you can either reinstall the original packages or recreate the symbolic links or use the update-alternatives command to set the default version back to the original one.

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