prereq-macos.md

aliBuild prerequisites for macOS

ALICE software compiles just fine on macOS using Apple-provided build tools. We exclusively support the following two versions of macOS:

• Sierra (10.12)
• High Sierra (10.13)

Any other version of macOS has to be considered not supported. If you are in doubt about upgrading your operating system and you still don't see the new version here, then please refrain from upgrading.

Please follow these instructions every time you install a new macOS version and every time you get a newer Xcode! This is non-optional!

Get or upgrade Xcode

Xcode is the Apple-provided toolkit for developing software on Apple devices. Xcode is required as it contains the necessary compilers and build tools used by ALICE.

Get it from the App Store by clicking here: if the link does not work, just open the App Store and search for Xcode. The installation is free of charge, but it takes quite some space on your Mac.

When installed, open it: if it asks you to install additional required components, please approve the action.

Installation's not over yet. Additional components (the "command-line tools") are required. Open a terminal and run:

xcode-select --install

In case they are already installed, you'll see the following message:

xcode-select: error: command line tools are already installed, use "Software Update" to install updates

This is important: once Xcode and the command-line tools are installed, every update will occur graphically via the App Store.

Now, at your first installation, you need to accept the Xcode license. If the above command did not ask you anything, just open a terminal and write:

git

without any further option. You will be prompted in case there is a license to accept. In case the license has been accepted already, you'll just see the list of options for the git command.

Get or upgrade Homebrew

Homebrew is a command-line package manager for macOS. It is the most popular now, and it is the only one we support.

If you have other package managers installed, such as MacPorts or Fink, you must get rid of them before proceeding. They will conflict with Homebrew and ALICE software in a bad way.

Note that Homebrew does not run as root. Do not prepend sudo to any of the following commands!

Installation instructions are ridiculously simple on the website. Once Homebrew is installed, run (as suggested):

brew doctor

and fix any potential error highlighted by the tool. Errors and warnings should not be overlooked! Pay close attention to warnings concerning outdated Xcode/compiler versions: you must upgrade Xcode to the latest available version before proceeding any further!

When you are done fixing the warnings, upgrade all the currently installed Homebrew packages:

brew upgrade

It is now time to install a bunch of required packages. Copy and paste this to your terminal (warning: long line):

brew install autoconf automake boost coreutils gettext gmp hub isl libmpc libtool m4 modules mpfr openssl pkg-config readline modules

{% callout "Attention: automake troubles (and a temporary workaround!)" %} As of now (March 1, 2018) latest brew upgrade runs will install automake 1.16 which is known to be buggy.

First off, check if you are running automake 1.16: if not, just entirely skip this section and live happily. Run:

automake --version

If the first line says:

automake (GNU automake) 1.16

then you should apply this manual fix. If you see something different (such as 1.16.1) then you are fine.

While we wait for an upstream fix, there is a tricky way to get back to automake 1.15 on your system: you need to manually cd to the place Homebrew stores its recipes (which is a Git repository) and roll back a single change.

Remove all versions of automake first:

brew remove --force automake

Revert Homebrew's version bump manually:

cd /usr/local/Homebrew/Library/Taps/homebrew/homebrew-core
git revert 6f2d5981e77731a9a1ca360948c42d32c0d80d01 --no-edit

You should see:

[master 9de3930a7a] Revert "automake 1.16"
 1 file changed, 3 insertions(+), 3 deletions(-)

Now reinstall automake as usual:

brew install automake

When the problem is fixed upstream, we will publish information on how to reset the local Homebrew status to upstream. {% endcallout %}

Now, open your ~/.bash_profile (you should have a default one; create one if it does not exist, and bear in mind that ~ represents your home directory) and add the following content:

export PATH="/usr/local/opt/gettext/bin:/usr/local/bin:$PATH"

The line above tells your shell (assuming it's Bash) where to find Homebrew programs. To check if it works, close the terminal, open a new one, and type:

type autopoint

You should get as an answer:

autopoint is /usr/local/opt/gettext/bin/autopoint

Get or upgrade gfortran

Your Xcode installation is missing a Fortran compiler, unfortunately. We need it for some parts of our code, therefore you must install it.

The GCC project has a downloads page for macOS: get the version that corresponds to your operating system the most. This means that if gfortran for your operating system version is not out yet, you can safely download the one for the previous version.

Downloads are dmg files: just double-click on them with Finder and follow the graphical installation procedure.

When done, open a terminal and check if you can find it:

type gfortran

You should obtain:

gfortran is /usr/local/bin/gfortran

Disable System Integrity Protection

Since El Capitan (10.11), Apple has introduced a security feature called System Integrity Protection, or SIP.

At the moment, unfortunately, ALICE software requires this feature to be turned off.

To turn SIP off:

• Reboot your Mac in Recovery Mode. That is, before macOS starts up, hold down Command-R and keep both keys pressed until the Apple logo appears.
• From the Utilities menu open a Terminal.
• Type: csrutil disable: a message will notify the success of your operation.
• Select Restart from the  menu.

Note: you can always re-enable it using csrutil enable instead.

Get or upgrade pip

pip is the Python package manager. Our build tool aliBuild and other Python dependencies are installed through it.

In case you are using Python from Anaconda then you have pip already. Check it by typing:

type pip

at your shell prompt. In case you don't use Anaconda, please install pip with this command:

sudo easy_install pip

Note that you need admin permissions for running the above command. Once done, check that pip got installed under /usr/local/bin:

type pip

It should yield:

pip is /usr/local/bin/pip

Get or upgrade required Python packages

Some Python packages are required for building our software. They are mostly related to ROOT 6. Just run:

sudo pip install matplotlib numpy certifi ipython==5.1.0 ipywidgets ipykernel notebook metakernel pyyaml

It is important to specify the version of ipython.

Exclude your work directory from Spotlight

Mac users have two nice features, Time Machine for backups and Spotlight for searches, that might have a detrimental effect on your Mac's performances.

Spotlight, in particular, indexes every created file, and since during our build and installation processes we create a lot of files we don't really want to index, it's better to tell Spotlight not to index our working directory.

We are assuming our working directory is ~/alice. Before telling Spotlight to exclude it, we need to create an empty one, so in a Terminal do:

mkdir ~/alice

(you can also use the Finder for that.) Then, go to the  (Apple) menu → System preferences → Spotlight. Click on the Privacy tab, then hit the + sign at the bottom of the window. Now select the ~/alice directory and confirm.

You are now ready for installing aliBuild and start building ALICE software