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+# hafas - Commandline Public Transit Routing Interface
+
+**hafas** is a commandline client and Perl module for HAFAS pulic transit
+routing interfaces. See the [Travel::Routing::DE::HAFAS homepage](https://finalrewind.org/projects/Travel-Routing-DE-HAFAS/) for details.
+
+## Installation
+
+You have three installation options:
+
+* Installing the latest release from CPAN
+* Installation from source
+* Using a Docker image
+
+Except for Docker, **hafas** is available in your PATH after installation.
+You can run `hafas --version` to verify this. Documentation is available via
+`man hafas`.
+
+### Installation from CPAN
+
+Travel::Routing::DE::HAFAS releases are published on the Comprehensive Perl
+Archive Network (CPAN) and can be installed using standard Perl module tools
+such as `cpanminus`.
+
+Before proceeding, ensure that you have standard build tools (i.e. make,
+pkg-config and a C compiler) installed. You will also need the following
+libraries with development headers:
+
+* libssl
+* zlib
+
+Now, use a tool of your choice to install the module. Minimum working example:
+
+```
+cpanm Travel::Routing::DE::HAFAS
+```
+
+If you run this as root, it will install script and module to `/usr/local` by
+default.
+
+### Installation from Source
+
+In this variant, you must ensure availability of dependencies by yourself.
+You may use carton or cpanminus with the provided `Build.PL`, Module::Build's
+installdeps command, or rely on the Perl modules packaged by your distribution.
+
+To check whether dependencies are satisfied, run:
+
+```
+perl Build.PL
+```
+
+If it complains about "... is not installed" or "ERRORS/WARNINGS FOUND IN
+PREREQUISITES", it is missing dependencies.
+
+Once all dependencies are satisfied, use Module::Build to build, test and
+install the module. Testing is optional -- you may skip the "Build test"
+step if you like.
+
+If you downloaded a release tarball, proceed as follows:
+
+```
+./Build
+./Build test
+sudo ./Build install
+```
+
+If you are using the Git repository, use the following commands:
+
+```
+./Build
+./Build manifest
+./Build test
+sudo ./Build install
+```
+
+If you do not have superuser rights or do not want to perform a system-wide
+installation, you may leave out `Build install` and use **hafas** from the
+current working directory.
+
+With carton:
+
+```
+carton exec hafas --version
+```
+
+Otherwise (also works with carton):
+
+```
+perl -Ilocal/lib/perl5 -Ilib bin/hafas --version
+```
+
+### Running hafas-m via Docker
+
+A hafas image is available on Docker Hub. It is intended for testing
+purposes: due to the latencies involved in spawning a container for each
+hafas invocation, it is less convenient for day-to-day usage.
+
+Installation:
+
+```
+docker pull derfnull/hafas:latest
+```
+
+Use it by prefixing hafas commands with `docker run --rm
+derfnull/hafas:latest`, like so:
+
+```
+docker run --rm derfnull/hafas:latest --version
+```
+
+Documentation is not available in this image. Please refer to the
+[online hafas manual](https://man.finalrewind.org/1/hafas/) instead.