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Last modified: 2 January 2020


Platform Support

Python versions

CIAO 4.12 is only distributed with Python 3.5. The conda installation is compatible with Python 3.5, 3.6, or 3.7.

CIAO 4.12 is available as precompiled binaries for the following platforms:


The Linux builds are done on a CentOS 6.9 machine and have been fully tested on CentOS 7 and Ubuntu 18.04. The Linux build will not work on some older Linux operating systems, including CentOS 5 and earlier versions of Fedora or Ubuntu.

CIAO 4.12 does not run on standard installations of:

  • Any 32 bit Linux
  • Cent OS5
  • RHEL version 5 or lower
  • Slackware Linux (missing SELinux system library)
  • Any version of Windows
Windows Subsystem of Linux (WSL)

CIAO is not supported using any Linux distribution running under the Windows Subsystem for Linux (WSL). The CXC has not done any testing with this configuration.

Mac OS X

CIAO is built on macOSX 10.12 (Sierra) and is compatible with newer versions of macOSX through Catalina (10.15).

CIAO users upgrading to macOSX Catalina may be inhibited by Apple's latest security settings which restrict some applications access to folders in users' home directories. The watchout page has some suggestions to help.

Explanation of Platform Support

The CXC's commitment to support a platform - i.e. a version of an operating system - means that we undertake to fix bugs on that system. This requires that we are able to compile CIAO from source on each platform, which is a much greater commitment than simply providing a compatible binary. Additionally, it is typically necessary to support several versions of each operating system: former, current and new.

When we support a system:

  1. We test every tool on every platform via a large number of regression tests and scripts; this requires a greater amount of time when the number of systems increases.
  2. We have to have current machines running each of these systems.
  3. We make a tarball and install it on each system; this process is never problem-free, and takes manpower and time.

As a result, we are not able to support a larger number of systems than we currently do. We gather information from users on what platforms they are running (or want to use) in order to prevent the overextension of our resources. Please contact the CXC Helpdesk if you have input you would like the CXC to consider for the next release of CIAO.