How to Install GCC on Ubuntu 21.10

GCC, the GNU Compiler Collection is a compiler system developed to support various programming languages. GCC is a standard compiler for most projects related to GNU and Linux, including the Linux kernel.

Installing GCC on Ubuntu

Ubuntu repositories contain a build-essential package which contains the GCC compiler, g++, and make.

Update your existing system by running the following command,

  apt upgrade

apt install build-essential

Output:

[email protected]:~# apt install build-essential
Reading package lists... Done
Building dependency tree... Done
Reading state information... Done
The following additional packages will be installed:
  dpkg-dev fakeroot g++ g++-11 gcc gcc-11 libalgorithm-diff-perl libalgorithm-diff-xs-perl libalgorithm-merge-perl libasan6
  libatomic1 libc-dev-bin libc-devtools libc6-dev libcc1-0 libcrypt-dev libfakeroot libgcc-11-dev libgomp1 libitm1 liblsan0
  libnsl-dev libquadmath0 libstdc++-11-dev libtirpc-dev libtsan0 libubsan1 linux-libc-dev lto-disabled-list make manpages-dev
  rpcsvc-proto
Suggested packages:
  debian-keyring g++-multilib g++-11-multilib gcc-11-doc gcc-multilib autoconf automake libtool flex bison gdb gcc-doc
  gcc-11-multilib gcc-11-locales glibc-doc libstdc++-11-doc make-doc
The following NEW packages will be installed:
  build-essential dpkg-dev fakeroot g++ g++-11 gcc gcc-11 libalgorithm-diff-perl libalgorithm-diff-xs-perl
  libalgorithm-merge-perl libasan6 libatomic1 libc-dev-bin libc-devtools libc6-dev libcc1-0 libcrypt-dev libfakeroot
  libgcc-11-dev libgomp1 libitm1 liblsan0 libnsl-dev libquadmath0 libstdc++-11-dev libtirpc-dev libtsan0 libubsan1
  linux-libc-dev lto-disabled-list make manpages-dev rpcsvc-proto

If you want to install the manual page for GCC, run the below command,

apt-get install manpages-dev

After installing, to verify that GCC is successfully installed by checking the gcc version,

  gcc --version

Output:

[email protected]:~# gcc --version
gcc (Ubuntu 11.2.0-5ubuntu1) 11.2.0
Copyright (C) 2021 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

Compiling a Hello World Example

Create a basic C code source, eg: let's create hello world in C program and open hello.c file,

nano hello.c

Add the following code to hello.c file.

// hello.c
#include <stdio.h>

int main() {
    printf("Hello, world!\n");
    return 0;
}

Compile it into an executable and execute the hello program by running the following commands,

gcc hello.c -o hello

./hello

Output:

[email protected]:~# ./hello 
Hello, world!
[email protected]:~# 

Installing Multiple GCC Versions

Install and use multiple versions of GCC on Ubuntu 21.10,

Install the desired GCC and G++ versions by typing below command,

apt install gcc-8 g++-8 gcc-9 g++-9 gcc-10 g++-10

Now you have multiple versions of the GCC compiler installed, there’s a priority number that gets associated with each. The version with the highest priority will be the default system compiler.

You will have to run the commands below to set the default system compiler associating each with a priority.

update-alternatives --install /usr/bin/gcc gcc /usr/bin/gcc-10 100 --slave /usr/bin/g++ g++ /usr/bin/g++-10 --slave /usr/bin/gcov gcov /usr/bin/gcov-10
update-alternatives --install /usr/bin/gcc gcc /usr/bin/gcc-9 90 --slave /usr/bin/g++ g++ /usr/bin/g++-9 --slave /usr/bin/gcov gcov /usr/bin/gcov-9
update-alternatives --install /usr/bin/gcc gcc /usr/bin/gcc-8 80 --slave /usr/bin/g++ g++ /usr/bin/g++-8 --slave /usr/bin/gcov gcov /usr/bin/gcov-8

Later if you want to change the default version use the update-alternatives command

  update-alternatives --config gcc

Output:

[email protected]:~# update-alternatives --config gcc
There are 3 choices for the alternative gcc (providing /usr/bin/gcc).

  Selection    Path             Priority   Status
------------------------------------------------------------
* 0            /usr/bin/gcc-10   100       auto mode
  1            /usr/bin/gcc-10   100       manual mode
  2            /usr/bin/gcc-8    80        manual mode
  3            /usr/bin/gcc-9    90        manual mode

Press <enter> to keep the current choice[*], or type selection number:

You will be presented with a list of all installed GCC versions on your Ubuntu system, Select your choice and press Enter.

Done.