# Getting + installing gcc/g++ 4.9 on Ubuntu?

I am using a variety of C++11 and C++1y features; which is why I need this.

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You can install close to upstream version of GCC from Ubuntu Toolchain PPA: https://wiki.ubuntu.com/ToolChain#PPA_packages

sudo add-apt-repository ppa:ubuntu-toolchain-r/test
sudo apt-get update
sudo apt-get install g++-4.9


Tested on Ubuntu 14.04.

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I have Ubuntu 14.04 and that didn't work for me. Did you leave a step out? I don't see g++-4.9 in launchpad.net/~ubuntu-toolchain-r/+archive/test –  test May 6 '14 at 6:27
test, should work: gist.github.com/rutsky/bc40c6b4bee0ab5f9ee4 –  Vladimir Rutsky May 8 '14 at 21:20
But it doesn't work for me on 12.04: E: Unable to locate package gcc-4.9 E: Couldn't find any package by regex 'gcc-4.9' Looks like 12.04 was specifically is not supported by this repository, even though both newer and older versions of Ubuntu are supported. –  Nickolai Leschov May 16 '14 at 2:56
@Matthias Looks like gcc-4.9 is only available for Ubuntu 14.04. For other versions, the latest available version is gcc-4.8. I googled arround and found no ppa's of gcc-4.9 for prior versions of Ubuntu. There's always an option to compile it from source, but from reading the instructions I gathered that it is a daunting process for the unexperienced like me, and abandoned this idea. –  Nickolai Leschov May 25 '14 at 20:18
As a last step, I found it necessary to change the symbolic link /usr/bin/g++ from a target of /usr/bin/g++-4.8 to a target of /usr/bin/g++-4.9. ...or leave it unchanged but invoke g++-4.9 directly. Finally: std::regex support. –  DavidO Jun 17 '14 at 19:43

## Intro

teach a man to fish etc. etc.

How to build the source package and serve it from a local repository in an apt-friendly way. This will work on any distribution provided that dependencies can be satisfied/ This method does not require you to install build-deps for every package and polluting your machine with extraneous packages, this will let you keep up with packages as they get updated in debian experimental. It takes just a few minutes to do this once, and then can be reused to rebuild any package you need without relying on other people to package ppa for you or downloading a bunch of different .debs

The benefit of building vs. pulling raw .debs from debian is that this will build packages against the packages in your distribution which may differ in version/revision from what is used as build-dependencies for the debian distribution. This is more-or-less the process for backporting packages. You can also use any ubuntu distribution to build packages targeted at any other distribution (target in this case means build against the standard repository packages) with no hassle.

## Basic-How-to-Build-a-deb

Probably-required: packaging-dev (pulls build-essential pubilder ubuntu-dev-tools among others)

1. Set up pbuilder (this lets you build a package in a chroot without polluting your system with build-dependency packages)

• sudo pbuilder create,
• if you want to build for a specific distribution, (pbuilder uses the build system release in a chroot) you can use pbuilder-dist [precise/oneric/trusy/etc...] create
2. Get debian source

• pull-debian-source gcc-4.9 [4.9.0-6] specific debian revision is optional, but can be useful if you want to pull experimental/unstable/testing/stable revisions
• you can also pull from specific ubuntu distros by adding them to sources.list as a deb-src and using sudo apt-get src
3. Build Package

• sudo pbuilder build gcc-4.9_4.9.0-6.dsc
• In the files downloaded there is a .dsc file, for the most recent gcc it is gcc-4.9_4.9.0-6.dsc which is a package descriptor file. .orig.tar.[gz/xz] is the source tarball.
4. Create local Apt-repository

• mkdir /convenient/place/for/repo
• cp /var/cache/pbuilder/result/* /path/to/repo
• (assuming you are in repo dir) apt-ftp archive packages . > Packages
• (one of many ways to do this) sudo echo "deb [trusted=yes] file:/local/repo/Packages ./" > /etc/apt/sources.list.d/gcc-repo.list
• Note you can also do this step with .debs downloaded from anywhere (skip step 1-3)
5. Install

• apt-get update; apt-get install gcc-4.9 g++-4.9

## Extra Tricks

### Easy backporting Dependencies

Using self-compiled packages to satisfy dependencies when building packages. (I have it set up with folders ~/pbuilder ~/pbuilder/precise_local (local package repo for precise) and ~/pbuilder/precise_hooks (for hook scripts) )

Add the following to your ~/.pbuilderrc

OTHERMIRROR="deb [trusted=yes] file:///home/user/pbuilder/precise_local ./"

BINDMOUNTS="/home/user/pbuilder/precise_local"

HOOKDIR="/home/user/pbuilder/precise_hooks"

EXTRAPACKAGES="apt-utils"


in precise_hooks create a file D05local (in typical unix/linux fashion, prefix D tells when script is hooked 05 is self-imposed name-ordering and local is just the name, if you only have one hook it is not important what its called as long as D is the prefix

the script is a one-liner

(cd /home/user/pbuilder/precise_local ; apt-ftparchive packages . > Packages)

Now any packages placed in precise_local will satisfy build-depends. This is supremely useful to construct a dependency tree locally when back-porting packages that have dependencies that also need backporting

### The VM solution

To do this in an even cleaner way, use a VM image or LXC container to jail this mess.

### Applying custom patches

you can apply custom patches in most debian packages using quilt, quilt patches can use diffs from most VCSs (see : using quilt )

There is an additional step, you must rebuild the .dsc and .debian.tar.gz. Cleanest-way I know is bzr-builddeb it has the highest success rate IMHO (compared to git-build-package and other helper scripts) and is much cleaner than calling debuild directly (bzr= bazaar canonical's VCS)

1. sudo apt-get install bzr-builddeb
2. (assuming .orig.tar.gz is extracted and .debian.tar.gz is extracted and place in it
• bzr init
• bzr add
• bzr commit
3. (OPTIONAL)
• modify debian/changelog
• add patch to debian/patches/ and modify debian/patches/series (quilt also has utility to add patches or for you to modify on the fly, see documentation)
• bzr add debian/
• bzr commit
4. bzr builddeb -- -S -us -uc This rebuilds the source file and leaves it unsigned (gpg signing required for PPA/distro uploading, but not for private local repos)
5. cd ../build-area/ Continue from Step 3 above.

Steps 1-4 here are pretty much what you need to upload to a PPA (they do not take binary files), but you require some steps to satisfy launchpad bureaucracy (this answer provides a explanation, this one has some links)

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Really cool :-) –  Marcos Roriz Junior Jun 12 '14 at 17:46
some steps are missing for 14.04. sudo pbuilder build gcc-4.9_4.9.0-6.dsc fails. –  J.F. Sebastian Oct 25 '14 at 1:13

Debian offers a package: https://packages.debian.org/experimental/gcc-4.9 - To prevent causing issues with Ubuntu/Debian compatibility; don't add it to your sources.list.

binutils_2.24-3_amd64.deb
cpp-4.9_4.9-20140218-1_amd64.deb
g++-4.9_4.9-20140218-1_amd64.deb
gcc-4.9_4.9-20140218-1_amd64.deb
gcc-4.9-base_4.9-20140218-1_amd64.deb
libasan1_4.9-20140218-1_amd64.deb
libatomic1_4.9-20140218-1_amd64.deb
libcilkrts5_4.9-20140218-1_amd64.deb
libgcc1_4.9-20140218-1_amd64.deb
libgcc-4.9-dev_4.9-20140218-1_amd64.deb
libgomp1_4.9-20140218-1_amd64.deb
libitm1_4.9-20140218-1_amd64.deb
liblsan0_4.9-20140218-1_amd64.deb
libmpfr4_3.1.2-1_amd64.deb
libstdc++-4.9-dev_4.9-20140218-1_amd64.deb
libstdc++6_4.9-20140218-1_amd64.deb
libtsan0_4.9-20140218-1_amd64.deb
libubsan0_4.9-20140218-1_amd64.deb
libvtv0_4.9-20140218-1_amd64.deb


From Debian's servers, e.g.:

http://ftp.us.debian.org/debian/pool/main/g/gcc-4.9/libgcc-4.9-dev_4.9-20140218-1_amd64.deb

Then install them, e.g.: $for package in *.deb; do sudo dpkg --install "$package"; done

[Easier just to run that bash loop a few times until all the dependencies are covered than remembering the order you downloaded them in!]

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install

sudo su -
apt-get install build-essential
apt-get update
apt-get install gcc-4.9 g++-4.9 cpp-4.9


after that if you check the version of gcc you will find the old version

gcc --version


so we can fix it with simple symbolic

cd /usr/bin
rm gcc g++ cpp
ln -s gcc-4.9 gcc
ln -s g++-4.9 g++
ln -s cpp-4.9 cpp


### or

you can update using update-alternatives

// Actually i tried the symbolic & i know this will work but you may use the symbolic to get it without problems // please correct me if I am wrong

update-alternatives --install /usr/bin/gcc gcc /usr/bin/gcc-4.9 40 --slave /usr/bin/gcc gcc /usr/bin/gcc-4.9
update-alternatives --config gcc
update-alternatives --install /usr/bin/cpp cpp /usr/bin/cpp-4.9 40 --slave /usr/bin/cpp cpp /usr/bin/cpp-4.9
update-alternatives --config cpp
update-alternatives --install /usr/bin/g++ g++ /usr/bin/g++-4.9 40 --slave /usr/bin/g++ g++ /usr/bin/g++-4.9
update-alternatives --config g++


### or

you can just compile with

/usr/bin/gcc4.9 filename.c


gcc-4.9 is just like the gcc-4.8 "ubuntu 14.04 gcc" it is not a big deference

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gcc 4.9 has a hell of big difference with 4.8, and its on opnenmp 4.0 support. –  jaky keeper Aug 12 '14 at 15:01
can you get me the difference please ! –  hwez Aug 12 '14 at 18:11
It has c++1y (C++14) support, for starters. –  Drew Noakes Aug 30 '14 at 14:33
Article on gcc 4.9 features: isocpp.org/blog/2014/04/gcc-4.9.0 –  Kurt Krueckeberg Oct 8 '14 at 18:55

Currently (20141102) adding the PPA and invoking the above command apt-get install gcc-4.9 g++-4.9 cpp-4.9 will print out a slew of suggested packages. Install them all except for libvtv0-dbg (which has a dependency conflict):

apt-get install gcc-4.9 g++-4.9 cpp-4.9 gcc-4.9-locales g++-4.9-multilib libstdc++6-4.9-dbg gcc-4.9-multilib libgcc1-dbg libgomp1-dbg libitm1-dbg libatomic1-dbg libasan1-dbg liblsan0-dbg libtsan0-dbg libubsan0-dbg libcilkrts5-dbg libquadmath0-dbg lib32stdc++6-4.9-dbg libx32stdc++6-4.9-dbg


(skip the -dbg packages if they're of no interest to you), and then do an apt-get dist-upgrade --auto-remove. That last step will basically replace your gcc-4.8 with gcc-4.9 (but not uninstall the older version), and pull in up-to-date fortran compilers at the same time.

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