Section 3.1.  Installing on Linux

3.1. Installing on Linux As with many open source projects, the primary platform of installation for Subversion is Linux. Although Subversion is far from a second-class citizen on other operating systems, such as Microsoft Windows or Apple's Mac OS X, Linux is where it feels most at home. Of course, Linux is not a single entity. There are, in fact, a wide variety of different distributions, each with its own slightly different filesystem layouts and package management systems for installation of software. As I said in the chapter introduction, describing all of these different distributions is well beyond the scope of this book. Instead, in this section I will show you how to compile and install Subversion from source, which should work for most Linux distributions. If you would rather install binaries with your distribution's package management system, you will find that there are binary packages available for most of the major distributions on the downloads page for Subversion. 3.1.1. Subversion's Prerequisites In order to make compiling a Subversion client easy, Subversion includes most of the dependencies it needs for the client in the Subversion source distribution. On the other hand, if you want to compile a server, there are a number of different prerequisites that you need to install first. Which prerequisites you use depends on exactly which features of Subversion you need. If you read on, I describe each of the packages that you may need to install, as well as the functionality they provide and where you might find them. Apache Portable Runtime Libraries The Apache Portable Runtime (APR) libraries are a set of libraries that provide a cross-platform abstraction layer for developing software that will work the same on a variety of different operating systems. Subversion is built on top of APR, and makes heavy use of the library, which helps ensure that SVN runs on the variety of platforms it supports. APR is therefore a core library for SVN, and is required when building the system. The APR libraries are available for download from a variety of mirrors, which can be reached from the Apache project's Web site, at apr.apache.org. Downloading the APR libraries is not usually necessary though, because the APR source necessary for compiling Subversion is included in the Subversion source distribution. Most compiled binary distributions of Subversion also include the necessary APR libraries, so installing them separately will likely be unnecessary. Apache Web Server Subversion uses the Apache Web server as one of the two servers it supports for allowing remote access to the repository. If you want support for using the Subversion extensions to WebDAV for accessing the repository, you will need Apache. If you would rather use the Subversion custom-protocolbased svnserve, or only want to use Subversion on the local machine, you do not need to compile Subversion with support for Apache. Most Linux distributions include Apache as a part of their core packages, and your system likely already has it installed. This may not be what you need though. Subversion requires version 2.0 or later of Apache, which is not yet in predominant use, and is often not installed. If you cannot upgrade your whole system to use Apache 2, it is possible to install Apache 2 alongside an existing version of Apache 1. I will show you how to set up such a system in Section 3.4, "Configuring to Use Apache." If you want to download the sources for Apache to compile them yourself, they can be obtained from mirrors linked from the Apache Web site, just like APR. You can download Apache from its site at httpd.apache.org. The Apache Web site also provides compiled binary versions of Apache for most platforms if you need to install Apache but don't want to compile it yourself. Unlike APR, Apache is not included with the Subversion source and must be installed separately. Berkeley DB The Berkeley DB (BDB) database is an embedded database, developed as an open source project by Sleepycat Software. It is a database system designed to be integrated into other programs, and is used by Subversion for its database repository backend. Berkeley DB is only required if you are going to use the Subversion database repository. If you are instead using the new filesystem-based repository introduced in version 1.1 of Subversion, you can compile without support for Berkeley DB. Most binary distributions of Subversion will include the necessary BDB support, so you shouldn't have to acquire BDB separately. If you are compiling Subversion from scratch, or are using an installation package that doesn't include BDB, you will need to install BDB yourself in order to have support for BDB-based repositories (most Linux distributions will already have it installed, so you might want to check before attempting to install it yourself). You can download BDB from Sleepycat's Web site, at www.sleepycat.com. Neon Subversion uses the Neon library in its client for communications with a WebDAV server. In most cases, you will not have to download this library separately, because it is included in the Subversion source distribution. If you are installing binary packages, however, you may need to install this as one of the prerequisites. The binary packages you will need, however, are in most cases available from the same place as the Subversion package that you are installing. 3.1.2. Downloading the Source The Subversion source code can be downloaded from the Subversion project's Web site, at subversion.tigris.org/project_packages.html, which is where you will also find a variety of already compiled binary packages for various operating systems and distributions. Source versions are available in a variety of archive formats (tar gzip, tar bzip2, and zip). If you're compiling on a UNIX-based system, you'll probably want to download either the bzip2 archive for the latest version of SVN (.tar.bz2 extension) or the gzip archive (.tar.gz). After you have the source archive for Subversion downloaded, it's time to get things unpacked, so that you can start compiling. To perform the unpacking, you will want to send the decompressed file to the tar command for unpacking. The easiest way to perform both the decompression and unpacking is to decompress with either the gzip or bzip2 command (depending on the compressed version you downloaded), and use the -dc options to tell the command to decompress the file and then send the decompressed file to standard output. A pipe can then be used to send the decompressed file directly to tar, which you'll want to run with the xvf options to tell it to extract the archive from a file, verbosely, and a hyphen (-) to tell it to take the archive from standard input. So, for example, if you had downloaded the bzip2 compressed version 1.1.0 of Subversion, the command to unpack it would be $ bzip2 -dc subversion-1.1.0.tar.bz2 | tar xvf - The tar command will unpack everything into a directory named (in the case of the preceding version) subversion-1.1.0. 3.1.3. Compiling and Installing For the most part, compiling Subversion is straightforward. It auto-detects the presence of the various prerequisites that are required for compilation of the server, and decides whether it can build the server. If none of the prerequisites are installed, it will just compile the Subversion client (which doesn't have any prerequisites beyond what is included with the source). To perform a basic compilation, just cd into the Subversion directory that you unpacked in the previous section and run the following commands. $ ./configure $ make $ su Password: # make install In most cases, this compiles everything that you need, and installs everything in /usr/local/. Notice that the last command (make install) requires you to super-user to the root user, in order to have the proper permissions to perform a systemwide install of Subversion. Configuration Options Sometimes the default compile and install is not actually what you want. For instance, you may not want to compile the server with all of the possible features, even if the prerequisites are installed; or you may want to install to somewhere other than /usr/local/. In these instances, the Subversion configure script provides several options that you can set when it is run. I explain the ones you are most likely to run into in the following. If you would like to see the complete list, you can run ./configure -help. To configure the Subversion compilation with one of these options, you should run the configure script with the desired option passed as a command-line parameter. --prefix=PREFIX The prefix option specifies where Subversion should be installed. By default, this is in /usr/local/. If you would rather install Subversion somewhere else, pass configure the --prefix option, with PREFIX replaced by the path where you would like Subversion to be installed. For example, if you are installing SVN on a system where you don't have root privileges, you can run ./configure -prefix=$HOME/subversion to have Subversion installed in a directory named subversion in your home directory. --with-apache=PATH --without-apache These options tell the build scripts whether they should compile the Subversion server with support for Apache and WebDAV. The default behavior is for Apache to be included, but if for some reason you don't want Apache support to be compiled, passing --withoutapache to configure will disable it. Additionally, if Apache is installed in a nonstandard place on your system, you may have to tell configure where to find it. You can do that by passing the --with-apache option, with PATH replaced by the path to where Apache is installed. --with-berkeley-db=PATH --without-berkeley-db These options tell the build scripts whether they should compile the Subversion server with support for the Berkeley DB. The default behavior is for BDB to be included, but if you plan on using the filesystem-based repository storage, --without-berkeley-db will disable BDB (of course, you can still use the filesystem repository even if BDB support is compiled). Also, if Berkeley DB is installed in a nonstandard place on your system, you may have to tell configure where to find it. You can do that by passing the --with-berkeley-db option, with PATH replaced by the path to where BDB is installed. --disable-mod-activation By default, Subversion modifies your Apache httpd.conf file to enable the Subversion WebDAV module, mod_dav_svn, when you run make install. If you don't want it to make this modification, you can pass --disable-mod-activation to the configure script.