Runtime Configuration Area
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## Runtime Configuration Area

Subversion provides many optional behaviors that the user can control. Many of these options are of the kind that a user would wish to apply to all Subversion operations. So, rather than forcing users to remember command-line arguments for specifying these options and to use them for every operation they perform, Subversion uses configuration files, segregated into a Subversion configuration area.

The Subversion configuration area is a two-tiered hierarchy of option names and their values. Usually, this boils down to a special directory that contains configuration files (the first tier), which are just text files in standard INI format where “sections” provide the second tier. You can easily edit these files using your favorite text editor (such as Emacs or vi), and they contain directives read by the client to determine which of several optional behaviors the user prefers.

### Configuration Area Layout

The first time the svn command-line client is executed, it creates a per-user configuration area. On Unix-like systems, this area appears as a directory named `.subversion` in the user's home directory. On Win32 systems, Subversion creates a folder named `Subversion`, typically inside the `Application Data` area of the user's profile directory (which, by the way, is usually a hidden directory). However, on this platform, the exact location differs from system to system and is dictated by the Windows Registry.[61] We will refer to the per-user configuration area using its Unix name, `.subversion`.

In addition to the per-user configuration area, Subversion also recognizes the existence of a system-wide configuration area. This gives system administrators the ability to establish defaults for all users on a given machine. Note that the system-wide configuration area alone does not dictate mandatory policy—the settings in the per-user configuration area override those in the system-wide one, and command-line arguments supplied to the svn program have the final word on behavior. On Unix-like platforms, the system-wide configuration area is expected to be the `/etc/subversion` directory; on Windows machines, it looks for a `Subversion` directory inside the common `Application Data` location (again, as specified by the Windows Registry). Unlike the per-user case, the svn program does not attempt to create the system-wide configuration area.

The per-user configuration area currently contains three files—two configuration files (`config` and `servers`), and a `README.txt` file, which describes the INI format. At the time of their creation, the files contain default values for each of the supported Subversion options, mostly commented out and grouped with textual descriptions about how the values for the key affect Subversion's behavior. To change a certain behavior, you need only to load the appropriate configuration file into a text editor, and to modify the desired option's value. If at any time you wish to have the default configuration settings restored, you can simply remove (or rename) your configuration directory and then run some innocuous svn command, such as `svn --version`. A new configuration directory with the default contents will be created.

Subversion also allows you to override individual configuration option values at the command line via the `--config-option` option, which is especially useful if you need to make a (very) temporary change in behavior. For more about this option's proper usage, see the section called “svn Options”.

The per-user configuration area also contains a cache of authentication data. The `auth` directory holds a set of subdirectories that contain pieces of cached information used by Subversion's various supported authentication methods. This directory is created in such a way that only the user herself has permission to read its contents.

### Configuration and the Windows Registry

In addition to the usual INI-based configuration area, Subversion clients running on Windows platforms may also use the Windows Registry to hold the configuration data. The option names and their values are the same as in the INI files. The “file/section” hierarchy is preserved as well, though addressed in a slightly different fashion—in this schema, files and sections are just levels in the Registry key tree.

Subversion looks for system-wide configuration values under the `HKEY_LOCAL_MACHINE\Software\Tigris.org\Subversion` key. For example, the `global-ignores` option, which is in the `miscellany` section of the `config` file, would be found at `HKEY_LOCAL_MACHINE\Software\Tigris.org\Subversion\Config\Miscellany\global-ignores`. Per-user configuration values should be stored under `HKEY_CURRENT_USER\Software\Tigris.org\Subversion`.

Registry-based configuration options are parsed before their file-based counterparts, so they are overridden by values found in the configuration files. In other words, Subversion looks for configuration information in the following locations on a Windows system; lower-numbered locations take precedence over higher-numbered locations:

1. Command-line options

2. The per-user INI files

3. The per-user Registry values

4. The system-wide INI files

5. The system-wide Registry values

Also, the Windows Registry doesn't really support the notion of something being “commented out.” However, Subversion will ignore any option key whose name begins with a hash (`#`) character. This allows you to effectively comment out a Subversion option without deleting the entire key from the Registry, obviously simplifying the process of restoring that option.

The svn command-line client never attempts to write to the Windows Registry and will not attempt to create a default configuration area there. You can create the keys you need using the REGEDIT program. Alternatively, you can create a `.reg` file (such as the one in Example 7.1, “Sample registration entries (.reg) file”), and then double-click on that file's icon in the Explorer shell, which will cause the data to be merged into your Registry.

Example 7.1. Sample registration entries (.reg) file

    REGEDIT4

    [HKEY_LOCAL_MACHINE\Software\Tigris.org\Subversion\Servers\groups]

    [HKEY_LOCAL_MACHINE\Software\Tigris.org\Subversion\Servers\global]
    "#http-auth-types"="basic;digest;negotiate"
    "#http-compression"="yes"
    "#http-library"=""
    "#http-proxy-exceptions"=""
    "#http-proxy-host"=""
    "#http-proxy-password"=""
    "#http-proxy-port"=""
    "#http-proxy-username"=""
    "#http-timeout"="0"
    "#neon-debug-mask"=""
    "#ssl-authority-files"=""
    "#ssl-client-cert-file"=""
    "#ssl-client-cert-password"=""
    "#ssl-pkcs11-provider"=""
    "#ssl-trust-default-ca"=""
    "#store-auth-creds"="yes"
    "#store-passwords"="yes"
    "#store-plaintext-passwords"="ask"
    "#store-ssl-client-cert-pp"="yes"
    "#store-ssl-client-cert-pp-plaintext"="ask"
    "#username"=""

    [HKEY_CURRENT_USER\Software\Tigris.org\Subversion\Config\auth]
    "#password-stores"="windows-cryptoapi"

    [HKEY_CURRENT_USER\Software\Tigris.org\Subversion\Config\helpers]
    "#diff-cmd"=""
    "#diff-extensions"="-u"
    "#diff3-cmd"=""
    "#diff3-has-program-arg"=""
    "#editor-cmd"="notepad"
    "#merge-tool-cmd"=""

    [HKEY_CURRENT_USER\Software\Tigris.org\Subversion\Config\tunnels]

    [HKEY_CURRENT_USER\Software\Tigris.org\Subversion\Config\miscellany]
    "#enable-auto-props"="no"
    "#global-ignores"="*.o *.lo *.la *.al .libs *.so *.so.[0-9]* *.a *.pyc *.pyo *.rej *~ #*# .#* .*.swp .DS_Store"
    "#interactive-conflicts"="yes"
    "#log-encoding"=""
    "#mime-types-file"=""
    "#no-unlock"="no"
    "#preserved-conflict-file-exts"="doc ppt xls od?"
    "#use-commit-times"="no"

    [HKEY_CURRENT_USER\Software\Tigris.org\Subversion\Config\auto-props]

Example 7.1, “Sample registration entries (.reg) file” shows the contents of a `.reg` file, which contains some of the most commonly used configuration options and their default values. Note the presence of both system-wide (for network proxy-related options) and per-user settings (editor programs and password storage, among others). Also note that all the options are effectively commented out. You need only to remove the hash (`#`) character from the beginning of the option names and set the values as you desire.

### Configuration Options

In this section, we will discuss the specific runtime configuration options that Subversion currently supports.

#### Servers

The `servers` file contains Subversion configuration options related to the network layers. There are two special sections in this file—`[groups]` and `[global]`. The `[groups]` section is essentially a cross-reference table. The keys in this section are the names of other sections in the file; their values are globs—textual tokens that possibly contain wildcard characters—that are compared against the hostnames of the machine to which Subversion requests are sent.

    [groups]
    beanie-babies = *.red-bean.com
    collabnet = svn.collab.net

    [beanie-babies]
    …

    [collabnet]
    …

When Subversion is used over a network, it attempts to match the name of the server it is trying to reach with a group name under the `[groups]` section. If a match is made, Subversion then looks for a section in the `servers` file whose name is the matched group's name. From that section, it reads the actual network configuration settings.

The `[global]` section contains the settings that are meant for all of the servers not matched by one of the globs under the `[groups]` section. The options available in this section are exactly the same as those that are valid for the other server sections in the file (except, of course, the special `[groups]` section), and are as follows:

`http-auth-types`

  This is a semicolon-delimited list of HTTP authentication types which the client will deem acceptable. Valid types are `basic`, `digest`, and `negotiate`, with the default behavior being acceptance of any these authentication types. A client which insists on not transmitting authentication credentials in cleartext might, for example, be configured such that the value of this option is `digest;negotiate`—omitting `basic` from the list. (Note that this setting is only honored by Subversion's Neon-based HTTP provider module.)

`http-compression`

  This specifies whether Subversion should attempt to compress network requests made to DAV-ready servers. The default value is `yes` (though compression will occur only if that capability is compiled into the network layer). Set this to `no` to disable compression, such as when debugging network transmissions.

`http-library`

  Subversion provides a pair of repository access modules that understand its WebDAV network protocol. The original one, which shipped with Subversion 1.0, is `libsvn_ra_neon` (though back then it was called `libsvn_ra_dav`). Newer Subversion versions also provide `libsvn_ra_serf`, which uses a different underlying implementation and aims to support some of the newer HTTP concepts.

  At this point, `libsvn_ra_serf` is still considered experimental, though it appears to work in the common cases quite well. To encourage experimentation, Subversion provides the `http-library` runtime configuration option to allow users to specify (generally, or in a per-server-group fashion) which WebDAV access module they'd prefer to use—`neon` or `serf`.

`http-proxy-exceptions`

  This specifies a comma-separated list of patterns for repository hostnames that should be accessed directly, without using the proxy machine. The pattern syntax is the same as is used in the Unix shell for filenames. A repository hostname matching any of these patterns will not be proxied.

`http-proxy-host`

  This specifies the hostname of the proxy computer through which your HTTP-based Subversion requests must pass. It defaults to an empty value, which means that Subversion will not attempt to route HTTP requests through a proxy computer, and will instead attempt to contact the destination machine directly.

`http-proxy-password`

  This specifies the password to supply to the proxy machine. It defaults to an empty value.

`http-proxy-port`

  This specifies the port number on the proxy host to use. It defaults to an empty value.

`http-proxy-username`

  This specifies the username to supply to the proxy machine. It defaults to an empty value.

`http-timeout`

  This specifies the amount of time, in seconds, to wait for a server response. If you experience problems with a slow network connection causing Subversion operations to time out, you should increase the value of this option. The default value is `0`, which instructs the underlying HTTP library, Neon, to use its default timeout setting.

`neon-debug-mask`

  This is an integer mask that the underlying HTTP library, Neon, uses for choosing what type of debugging output to yield. The default value is `0`, which will silence all debugging output. For more information about how Subversion makes use of Neon, see Chapter 8, Embedding Subversion.

`ssl-authority-files`

  This is a semicolon-delimited list of paths to files containing certificates of the certificate authorities (or CAs) that are accepted by the Subversion client when accessing the repository over HTTPS.

`ssl-client-cert-file`

  If a host (or set of hosts) requires an SSL client certificate, you'll normally be prompted for a path to your certificate. By setting this variable to that same path, Subversion will be able to find your client certificate automatically without prompting you. There's no standard place to store your certificate on disk; Subversion will grab it from any path you specify.

`ssl-client-cert-password`

  If your SSL client certificate file is encrypted by a passphrase, Subversion will prompt you for the passphrase whenever the certificate is used. If you find this annoying (and don't mind storing the password in the `servers` file), you can set this variable to the certificate's passphrase. You won't be prompted anymore.

`ssl-pkcs11-provider`

  The value of this option is the name of the PKCS#11 provider from which an SSL client certificate will be drawn (if the server asks for one). This setting is only honored by Subversion's Neon-based HTTP provider module.

`ssl-trust-default-ca`

  Set this variable to `yes` if you want Subversion to automatically trust the set of default CAs that ship with OpenSSL.

`store-auth-creds`

  This setting is the same as `store-passwords`, except that it enables or disables on-disk caching of all authentication information: usernames, passwords, server certificates, and any other types of cacheable credentials.

`store-passwords`

  This instructs Subversion to cache, or not to cache, passwords that are supplied by the user in response to server authentication challenges. The default value is `yes`. Set this to `no` to disable this on-disk password caching. You can override this option for a single instance of the svn command using the `--no-auth-cache` command-line parameter (for those subcommands that support it). For more information regarding that, see the section called “Caching credentials”. Note that regardless of how this option is configured, Subversion will not store passwords in plaintext unless the `store-plaintext-passwords` option is also set to `yes`.

`store-plaintext-passwords`

  This variable is only important on UNIX-like systems. It controls what the Subversion client does in case the password for the current authentication realm can only be cached on disk in unencrypted form, in the `~/.subversion/auth/` caching area. You can set it to `yes` or `no` to enable or disable caching of passwords in unencrypted form, respectively. The default setting is `ask`, which causes the Subversion client to ask you each time a new password is about to be added to the `~/.subversion/auth/` caching area.

`store-ssl-client-cert-pp`

  This option controls whether Subversion will cache SSL client certificate passphrases provided by the user. Its value defaults to `yes`. Set this to `no` to disable this passphrase caching.

`store-ssl-client-cert-pp-plaintext`

  This option controls whether Subversion, when attempting to cache an SSL client certificate passphrase, will be allowed to do so using its on-disk plaintext storage mechanism. The default value of this option is `ask`, which causes the Subversion client to ask you each time a new client certificate passphrase is about to be added to the `~/.subversion/auth/` caching area. Set this option's value to `yes` or `no` to indicate your preference and avoid related prompts.

#### Config

The `config` file contains the rest of the currently available Subversion runtime options—those not related to networking. There are only a few options in use as of this writing, but they are again grouped into sections in expectation of future additions.

The `[auth]` section contains settings related to Subversion's authentication and authorization against the repository. It contains the following:

`password-stores`

  This comma-delimited list specifies which (if any) system-provided password stores Subversion should attempt to use when saving and retrieving cached authentication credentials, and in what order Subversion should prefer them. The default value is `gnome-keyring, kwallet, keychain, windows-crypto-api`, representing the GNOME Keyring, KDE Wallet, Mac OS X Keychain, and Microsoft Windows cryptography API, respectively. Listed stores which are not available on the system are ignored.

`store-passwords`

  This option has been deprecated from the `config` file. It now lives as a per-server configuration item in the `servers` configuration area. See the section called “Servers” for details.

`store-auth-creds`

  This option has been deprecated from the `config` file. It now lives as a per-server configuration item in the `servers` configuration area. See the section called “Servers” for details.

The `[helpers]` section controls which external applications Subversion uses to accomplish its tasks. Valid options in this section are:

`diff-cmd`

  This specifies the absolute path of a differencing program, used when Subversion generates “diff” output (such as when using the svn diff command). By default, Subversion uses an internal differencing library—setting this option will cause it to perform this task using an external program. See the section called “Using External Differencing and Merge Tools” for more details on using such programs.

`diff-extensions`

  Like the `--extensions` (`-x`) command-line option, this specifies additional options passed to the file content differencing engine. The set of meaningful extension options differs depending on whether the client is using Subversion's internal differencing engine or an external mechanism. See the output of `svn help diff` for details. The default value for this option is `-u`.

`diff3-cmd`

  This specifies the absolute path of a three-way differencing program. Subversion uses this program to merge changes made by the user with those received from the repository. By default, Subversion uses an internal differencing library—setting this option will cause it to perform this task using an external program. See the section called “Using External Differencing and Merge Tools” for more details on using such programs.

`diff3-has-program-arg`

  This flag should be set to `true` if the program specified by the `diff3-cmd` option accepts a `--diff-program` command-line parameter.

`editor-cmd`

  This specifies the program Subversion will use to query the user for certain types of textual metadata or when interactively resolving conflicts. See the section called “Using External Editors” for more details on using external text editors with Subversion.

`merge-tool-cmd`

  This specifies the program that Subversion will use to perform three-way merge operations on your versioned files. See the section called “Using External Differencing and Merge Tools” for more details on using such programs.

The `[tunnels]` section allows you to define new tunnel schemes for use with svnserve and `svn://` client connections. For more details, see the section called “Tunneling over SSH”.

The `miscellany` section is where everything that doesn't belong elsewhere winds up.[62] In this section, you can find:

`enable-auto-props`

  This instructs Subversion to automatically set properties on newly added or imported files. The default value is `no`, so set this to `yes` to enable this feature. The `[auto-props]` section of this file specifies which properties are to be set on which files.

`global-ignores`

  When running the svn status command, Subversion lists unversioned files and directories along with the versioned ones, annotating them with a `?` character (see the section called “See an overview of your changes”). Sometimes it can be annoying to see uninteresting, unversioned items—for example, object files that result from a program's compilation—in this display. The `global-ignores` option is a list of whitespace-delimited globs that describe the names of files and directories that Subversion should not display unless they are versioned. The default value is `*.o *.lo *.la *.al .libs *.so *.so.[0-9]* *.a *.pyc *.pyo *.rej *~ #*# .#* .*.swp .DS_Store`.

  As well as svn status, the svn add and svn import commands also ignore files that match the list when they are scanning a directory. You can override this behavior for a single instance of any of these commands by explicitly specifying the filename, or by using the `--no-ignore` command-line flag.

  For information on finer-grained control of ignored items, see the section called “Ignoring Unversioned Items”.

`interactive-conflicts`

  This is a Boolean option that specifies whether Subversion should try to resolve conflicts interactively. If its value is `yes` (which is the default value), Subversion will prompt the user for how to handle conflicts in the manner demonstrated in the section called “Resolve Any Conflicts”. Otherwise, it will simply flag the conflict and continue its operation, postponing resolution to a later time.

`log-encoding`

  This variable sets the default character set encoding for commit log messages. It's a permanent form of the `--encoding` option (see the section called “svn Options”). The Subversion repository stores log messages in UTF-8 and assumes that your log message is written using your operating system's native locale. You should specify a different encoding if your commit messages are written in any other encoding.

`mime-types-file`

  This option, new to Subversion 1.5, specifies the path of a MIME types mapping file, such as the `mime.types` file provided by the Apache HTTP Server. Subversion uses this file to assign MIME types to newly added or imported files. See the section called “Automatic Property Setting” and the section called “File Content Type” for more about Subversion's detection and use of file content types.

`no-unlock`

  This Boolean option corresponds to svn commit's `--no-unlock` option, which tells Subversion not to release locks on files you've just committed. If this runtime option is set to `yes`, Subversion will never release locks automatically, leaving you to run svn unlock explicitly. It defaults to `no`.

`preserved-conflict-file-exts`

  The value of this option is a space-delimited list of file extensions that Subversion should preserve when generating conflict filenames. By default, the list is empty. This option is new to Subversion 1.5.

  When Subversion detects conflicting file content changes, it defers resolution of those conflicts to the user. To assist in the resolution, Subversion keeps pristine copies of the various competing versions of the file in the working copy. By default, those conflict files have names constructed by appending to the original filename a custom extension such as `.mine` or `.`REV`` (where `REV` is a revision number). A mild annoyance with this naming scheme is that on operating systems where a file's extension determines the default application used to open and edit that file, appending a custom extension prevents the file from being easily opened by its native application. For example, if the file `ReleaseNotes.pdf` was conflicted, the conflict files might be named `ReleaseNotes.pdf.mine` or `ReleaseNotes.pdf.r4231`. While your system might be configured to use Adobe's Acrobat Reader to open files whose extensions are `.pdf`, there probably isn't an application configured on your system to open all files whose extensions are `.r4231`.

  You can fix this annoyance by using this configuration option, though. For files with one of the specified extensions, Subversion will append to the conflict file names the custom extension just as before, but then also reappend the file's original extension. Using the previous example, and assuming that `pdf` is one of the extensions configured in this list thereof, the conflict files generated for `ReleaseNotes.pdf` would instead be named `ReleaseNotes.pdf.mine.pdf` and `ReleaseNotes.pdf.r4231.pdf`. Because each file ends in `.pdf`, the correct default application will be used to view them.

`use-commit-times`

  Normally your working copy files have timestamps that reflect the last time they were touched by any process, whether your own editor or some svn subcommand. This is generally convenient for people developing software, because build systems often look at timestamps as a way of deciding which files need to be recompiled.

  In other situations, however, it's sometimes nice for the working copy files to have timestamps that reflect the last time they were changed in the repository. The svn export command always places these “last-commit timestamps” on trees that it produces. By setting this config variable to `yes`, the svn checkout, svn update, svn switch, and svn revert commands will also set last-commit timestamps on files that they touch.

The `[auto-props]` section controls the Subversion client's ability to automatically set properties on files when they are added or imported. It contains any number of key-value pairs in the format ``PATTERN` = `PROPNAME`=`VALUE`[;`PROPNAME`=`VALUE` ...]`, where `PATTERN` is a file pattern that matches one or more filenames and the rest of the line is a semicolon-delimited set of property assignments. (If you need to use a semicolon in your property's name or value, you can escape it by doubling it.)

    $ cat ~/.subversion/config
    …
    [auto-props]
    *.c = svn:eol-style=native
    *.html = svn:eol-style=native;svn:mime-type=text/html;; charset=UTF8
    *.sh = svn:eol-style=native;svn:executable
    …
    $ cd projects/myproject
    $ svn status
    ?       www/index.html
    $ svn add www/index.html
    A         www/index.html
    $ svn diff www/index.html
    …

    Property changes on: www/index.html
    ___________________________________________________________________
    Added: svn:mime-type
    ## -0,0 +1 ##
    +text/html; charset=UTF8
    Added: svn:eol-style
    ## -0,0 +1 ##
    +native
    $

Multiple matches on a file will result in multiple propsets for that file; however, there is no guarantee that auto-props will be applied in the order in which they are listed in the config file, so you can't have one rule “override” another. You can find several examples of auto-props usage in the `config` file. Lastly, don't forget to set `enable-auto-props` to `yes` in the `miscellany` section if you want to enable auto-props.

[61] The `APPDATA` environment variable points to the `Application Data` area, so you can always refer to this folder as `%APPDATA%\Subversion`.

[62] Anyone for potluck dinner?

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