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askubuntu.com › questions › 466651 › how-do-i-use-the-latest-gcc-on-ubuntu

The best way to correctly install gcc-4.9 and set it as your default gcc version use:

sudo add-apt-repository ppa:ubuntu-toolchain-r/test
sudo apt-get update
sudo apt-get install gcc-4.9 g++-4.9
sudo update-alternatives --install /usr/bin/gcc gcc /usr/bin/gcc-4.9 60 --slave /usr/bin/g++ g++ /usr/bin/g++-4.9

The --slave, with g++, will cause g++ to be switched along with gcc, to the same version. But, at this point gcc-4.9 will be your only version configured in update-alternatives, so add 4.8 to update-alternatives, so there actually is an alternative, by using:

sudo apt-get install gcc-4.8 g++-4.8
sudo update-alternatives --install /usr/bin/gcc gcc /usr/bin/gcc-4.8 60 --slave /usr/bin/g++ g++ /usr/bin/g++-4.8

Then you can check which one that is set, and change back and forth using:

sudo update-alternatives --config gcc

If you have an issue with update-alternatives gcc priority 60 not being higher than previous versions installed you can use the previous update-alternatives --config gcc command to check installed versions and use:

sudo update-alternatives --remove gcc

Or:

sudo update-alternatives --remove-all gcc

NOTE: You could skip installing the PPA Repository and just use /usr/bin/gcc-4.9-base but I prefer using the fresh updated toolchains.

For GCC 5.X or 6, the packages (and correspondingly, the commands) are just called gcc-5, gcc-6, etc. This is due to the change in GCC's version scheme, where 5.1 is the first GCC 5 release, and future 5.X releases are for bug fixes.

Answer from SudoSURoot on askubuntu.com

Ask Ubuntu

askubuntu.com › questions › 466651 › how-do-i-use-the-latest-gcc-on-ubuntu

software installation - How do I use the latest GCC on Ubuntu? - Ask Ubuntu

Top answer

1 of 5

240

The best way to correctly install gcc-4.9 and set it as your default gcc version use:

sudo add-apt-repository ppa:ubuntu-toolchain-r/test
sudo apt-get update
sudo apt-get install gcc-4.9 g++-4.9
sudo update-alternatives --install /usr/bin/gcc gcc /usr/bin/gcc-4.9 60 --slave /usr/bin/g++ g++ /usr/bin/g++-4.9

sudo apt-get install gcc-4.8 g++-4.8
sudo update-alternatives --install /usr/bin/gcc gcc /usr/bin/gcc-4.8 60 --slave /usr/bin/g++ g++ /usr/bin/g++-4.8

Then you can check which one that is set, and change back and forth using:

sudo update-alternatives --config gcc

sudo update-alternatives --remove gcc

Or:

sudo update-alternatives --remove-all gcc

NOTE: You could skip installing the PPA Repository and just use /usr/bin/gcc-4.9-base but I prefer using the fresh updated toolchains.

2 of 5

Ultimate mega master compatibility table

OK let's do this:

                  GCC                              clang
        +-------------------------------------+-------------------------------------------------+
        | 15 14 13 12 11 10  9  8  7  6  5  4 | 20 19 18 17 16 15 14 13 12 11 10  9  8  7  6  5 |
+-------+-------------------------------------+-------------------------------------------------+
| 25.10 |  D  M  M  M  M                      |  D  M  M  M                                     |
| 25.04 |     D  M  M  M                      |  D  M  M  M                                     |
| 24.10 |     D  M  M  M                      |     D  M  M  M  M  M                            |
| 24.04 |     M  D  M  M  M  M                |        D  M  M  M  M                            |
| 23.10 |        D  M  M  M  M                |           M  D  M  M  M                         |
| 23.10 |        D  M  M  M  M                |              D  M  M  M                         |
| 23.04 |        M  D  M  M  M                |              M  D  M  M                         |
| 22.10 |           D  M  M  M                |                 D  M  M                         |
| 22.04 |        P  M  D  M  M                |                    D  M  M  M                   |
| 21.10 |              D  M  M  M             |                       D  M  M  M  M             |
| 21.04 |              M  D  M  M  M          |                          D  M  M  M             |
| 20.10 |                 D  M  M  M          |                             D  M  M  M  M  M    |
| 20.04 |                 P  D  M  M          |                                D  M  M  M  M    |
| 19.10 |                    D  M  M          |                                                 |
| 19.04 |                    M  D  M  M       |                                                 |
| 18.10 |                       D  M  M  M    |                                                 |
| 18.04 |                 P  P  M  D  M  M    |                                   M  M  M  D  M |
| 16.04 |                    P  P  P  P  D  M |                                                 |
+-------+-------------------------------------+-------------------------------------------------+

D: Default GCC
```
sudo apt-get update
sudo apt-get install gcc g++
gcc --version
```
Whatever the gcc package aliases to: https://packages.ubuntu.com/search?keywords=gcc and also present in manifests: How do I list the default installed packages?
M: Present in Main repo
```
sudo apt-get update
sudo apt-get install gcc-X g++-X
gcc-X --version
```
All Ubuntu versions that have a hit for a given GCC version, e.g. for GCC 7: https://packages.ubuntu.com/search?keywords=gcc-7 or clang 7 https://packages.ubuntu.com/search?keywords=clang-7

The minor versions of these packages can get updated from time to time within a single Ubuntu version (on the . revisions?), e.g. 8.3.0 to 8.4.0 so we are not keeping track of that.
P: ppa:ubuntu-toolchain-r/test, which is owned by Ubuntu people and therefore can be trusted to not be a virus, although it is possibly unstable:
```
sudo add-apt-repository ppa:ubuntu-toolchain-r/test
sudo apt-get update
sudo apt-get install gcc-X g++-X
gcc-X --version
```
Full list: https://launchpad.net/~ubuntu-toolchain-r/+archive/ubuntu/test

The minor versions of these packages can get updated from time to time, e.g. 8.3.0 to 8.4.0.

Blank spaces on the table mean either "no package available" or "I didn't bother to check". Notably I've not been looking into PPA packages too thoroughly. Edits accepted.

All the questions:

install gcc-9 on Ubuntu 18.04?
How to install gcc-7 or clang 4.0?
install gcc-9 on Ubuntu 18.04?
What are the GCC and clang versions available in Ubuntu 18.04?

How to set a non-default GCC as the default?

E.g., you installed /usr/bin/gcc-7 but you want to use that instead of /usr/bin/gcc when you run gcc main.c.

Use sudo update-alternatives as mentioned in other answers: https://askubuntu.com/a/581497/52975 It creates the required symlinks for you.

See also: What exactly does `update-alternatives` do?

How to build your own toolchain from source

If even the PPA is not old/new enough for you, see this:

https://stackoverflow.com/questions/847179/multiple-glibc-libraries-on-a-single-host/52454603#52454603
https://stackoverflow.com/questions/26305738/can-i-build-gcc-for-arm-with-an-x64-one/26306591#26306591

Older GCC version questions

Ubuntu 20.04 - gcc version lower than gcc-7
How to use an older version of GCC

Stack Overflow

stackoverflow.com › questions › 75384136 › update-gcc-on-ubuntu

c++ - Update GCC on Ubuntu - Stack Overflow

Top answer

1 of 1

This is a common pattern in linux. When there are multiple versions of the same program installed, though the executables are all present in the /usr/bin/ directory, only one of them is "visible" as that program. For example, if you install gcc-9 and gcc-10, both executables are present as /usr/bin/gcc-9 and /usr/bin/gcc-10 but only one of them is visible as gcc. This happens by symlinking a preferred version to the same directory as /usr/bin/gcc. In ubuntu 20.04, the preferred version is gcc-9 and so, gcc-9 is symlinked as gcc.

You can check this by running the following command.

$ which gcc | xargs file

The output will be

/usr/bin/gcc: symbolic link to gcc-9

There are a few things you can do to use gcc-10 as your c compiler.

Directly call the gcc-10 executable. Instead of using gcc <code.c>, call gcc-10 <code.c>.
You can manually symlink gcc-10 as the preferred gcc. Assuming you did not modify the system paths, the following command can be used.

# ln -s /usr/bin/gcc-10 /usr/local/bin/gcc

This works because, by default, the executables in /usr/local/bin/ take precedence over /usr/bin/.

If you are using bash, you can create an alias for gcc as gcc-10. Add the following line to your .bashrc.

alias gcc="gcc-10"

Remember to relaunch bash or source ~/.bashrc.

Using update-alternatives (Thanks to @ted-lyngmo for pointing it out). Debian based distributions supply a separate program, that can make symlinking easier / more functional. Read more using man update-alternatives. To use gcc-10 as the preferred gcc, use the following command.

# update-alternatives --install /usr/bin/gcc gcc /usr/bin/gcc-10 60

The above command says, /usr/bin/gcc is the link needed and the name is gcc, the target executable is /usr/bin/gcc-10 and it has a priority of 60.

This links gcc to /etc/alternatives/gcc, which itself is a symlink to /usr/bin/gcc-10. If a higher priority program is added to update-alternatives, /etc/alternatives/gcc points to the higher priority program.

If you don't have any specific reason, I would also recommend to upgrade to a newer ubuntu version, so that the default gcc is a newer one.

I read on the gcc website that version 9.4 is more up-to-date than some 10.x versions.

With newer gcc versions, new features are added. Support for newer c/c++ standards are also added. Eg. You can read the changes for gcc-10 here. But people still need gcc-9 because some programs only build with gcc-9. So, GNU maintains gcc-9 (and much older versions) for a long time. Bugs are fixed, and newer releases are made. This can happen after the release of a newer gcc version. So, it is very much possible that a version of gcc-9 is newer than a version of gcc-10.

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