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 (with “sections” providing 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.
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.
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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.
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.
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:
Command-line options
The per-user INI files
The per-user Registry values
The system-wide INI files
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-proxy-host"="" "#http-proxy-port"="" "#http-proxy-username"="" "#http-proxy-password"="" "#http-proxy-exceptions"="" "#http-timeout"="0" "#http-compression"="yes" "#neon-debug-mask"="" "#ssl-authority-files"="" "#ssl-trust-default-ca"="" "#ssl-client-cert-file"="" "#ssl-client-cert-password"="" [HKEY_CURRENT_USER\Software\Tigris.org\Subversion\Config\auth] "#store-passwords"="yes" "#store-auth-creds"="yes" [HKEY_CURRENT_USER\Software\Tigris.org\Subversion\Config\helpers] "#editor-cmd"="notepad" "#diff-cmd"="" "#diff3-cmd"="" "#diff3-has-program-arg"="" [HKEY_CURRENT_USER\Software\Tigris.org\Subversion\Config\tunnels] [HKEY_CURRENT_USER\Software\Tigris.org\Subversion\Config\miscellany] "#global-ignores"="*.o *.lo *.la #*# .*.rej *.rej .*~ *~ .#* .DS_Store" "#log-encoding"="" "#use-commit-times"="" "#no-unlock"="" "#enable-auto-props"="" [HKEY_CURRENT_USER\Software\Tigris.org\Subversion\Config\auto-props]
The previous example 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.
In this section, we will discuss the specific runtime configuration options that Subversion currently supports.
The servers file contains
Subversion configuration options related to the network
layers. There are two special section names 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-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-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-proxy-password
This specifies the password 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.
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-auth-types
This option is a semicolon-delimited list of
authentication types supported by the Neon-based
WebDAV repository access modules. Valid members of
this list are basic,
digest, and
negotiate.
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-trust-default-ca
Set this variable to yes if you
want Subversion to automatically trust the set of
default CAs that ship with OpenSSL.
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.
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.
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:
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, see the section called “Client Credentials Caching”.
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.
The helpers section controls which
external applications Subversion uses to accomplish its
tasks. Valid options in this section are:
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.
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.
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.
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.
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In this section, you can find:
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”.
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.
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.
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.
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.
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
.
(where REVREV 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.
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 Conflicts (Merging Others' Changes)”. Otherwise, it will simply flag the conflict and
continue its operation, postponing resolution to a later
time.
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.
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. 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.