The Trac Configuration File
Trac configuration is done by editing the trac.ini config file, located in <projectenv>/conf/trac.ini. Changes to the configuration are usually reflected immediately, though changes to the [components] or [logging] sections will require restarting the web server. You may also need to restart the web server after creating a global configuration file when none was previously present.
Global Configuration
In versions prior to 0.11, the global configuration was by default located in $prefix/share/trac/conf/trac.ini or sometimes /etc/trac/trac.ini depending on the distribution. If you're upgrading, you may want to specify that file to inherit from.
Literally, when you're upgrading to 0.11, you have to add an inherit-section to your project's trac.ini file. Additionally you have to move your customized templates and common images from $prefix/share/trac/... to the new location.
Global options will be merged with the environment-specific options, where local options override global options. The options file is specified as follows:
[inherit]
file = /usr/share/trac/conf/trac.ini
Note that you can also specify a global option file when creating a new project, by adding the option
--inherit=/path/to/global/options to trac-admin's initenv command.
If you would not do this but nevertheless intend to use a global option file with your new environment,
you would have to go through the newly generated conf/trac.ini file and delete the entries that would
otherwise override those set in the global file.
Reference
This is a brief reference of available configuration options.
[account-manager]
| account_changes_notify_addresses | List of email addresses that get notified of user changes, ie,
new user, password change and delete user. |
| authentication_url | |
| force_passwd_change | Forge the user to change password when it's reset. |
| generated_password_length | Length of the randomly-generated passwords created when resetting the password for an account. |
| hash_method | |
| htdigest_realm | |
| notify_actions | Comma separated list of actions to notify of.
Available actions 'new', 'change', 'delete'. |
| password_file | Path to the users file. Leave blank to locate the users file by reading svnserve.conf |
| password_format | |
| password_store | |
| persistent_sessions | Allow the user to be remembered across sessions without needing to re-authenticate. This is, user checks a "Remember Me" checkbox and, next time he visits the site, he'll be remembered |
| reset_password | Set to false if there is no email system setup. |
[attachment]
| max_size | Maximum allowed file size (in bytes) for ticket and wiki
attachments. |
| render_unsafe_content | Whether attachments should be rendered in the browser, or
only made downloadable.
Pretty much any file may be interpreted as HTML by the browser,
which allows a malicious user to attach a file containing cross-site
scripting attacks.
For public sites where anonymous users can create attachments it is
recommended to leave this option disabled (which is the default). |
[bitten]
| adjust_timestamps | Whether the timestamps of builds should be adjusted to be close
to the timestamps of the corresponding changesets. |
| build_all | Whether to request builds of older revisions even if a younger
revision has already been built. |
| logs_dir | The directory on the server in which client log files will be stored. |
| quick_status | Whether to show the current build status withing the Trac main
navigation bar |
| slave_timeout | The time in seconds after which a build is cancelled if the slave
does not report progress. |
| stabilize_wait | The time in seconds to wait for the repository to stabilize before
queuing up a new build. This allows time for developers to check in
a group of related changes back to back without spawning multiple
builds. |
[browser]
| color_scale | Enable colorization of the age column.
This uses the same color scale as the source code annotation:
blue is older, red is newer.
(since 0.11) |
| downloadable_paths | List of repository paths that can be downloaded.
Leave the option empty if you want to disable all downloads, otherwise
set it to a comma-separated list of authorized paths (those paths are
glob patterns, i.e. "*" can be used as a wild card)
(since 0.10) |
| hide_properties | Comma-separated list of version control properties to hide from
the repository browser.
(since 0.9) |
| intermediate_color | (r,g,b) color triple to use for the color corresponding
to the intermediate color, if two linear interpolations are used
for the color scale (see intermediate_point).
If not set, the intermediate color between oldest_color and
newest_color will be used.
(since 0.11) |
| intermediate_point | If set to a value between 0 and 1 (exclusive), this will be the
point chosen to set the intermediate_color for interpolating
the color value.
(since 0.11) |
| newest_color | (r,g,b) color triple to use for the color corresponding
to the newest color, for the color scale used in blame or
the browser age column if color_scale is enabled.
(since 0.11) |
| oldest_color | (r,g,b) color triple to use for the color corresponding
to the oldest color, for the color scale used in blame or
the browser age column if color_scale is enabled.
(since 0.11) |
| oneliner_properties | Comma-separated list of version control properties to render
as oneliner wiki content in the repository browser.
(since 0.11) |
| render_unsafe_content | Whether attachments should be rendered in the browser, or
only made downloadable.
Pretty much any file may be interpreted as HTML by the browser,
which allows a malicious user to attach a file containing cross-site
scripting attacks.
For public sites where anonymous users can create attachments it is
recommended to leave this option disabled (which is the default). |
| wiki_properties | Comma-separated list of version control properties to render
as wiki content in the repository browser.
(since 0.11) |
[changeset]
| max_diff_bytes | Maximum total size in bytes of the modified files (their old size
plus their new size) for which the changeset view will attempt to show
the diffs inlined (since 0.10). |
| max_diff_files | Maximum number of modified files for which the changeset view will
attempt to show the diffs inlined (since 0.10). |
| wiki_format_messages | Whether wiki formatting should be applied to changeset messages.
If this option is disabled, changeset messages will be rendered as
pre-formatted text. |
[datefield]
| change_month | Show a month dropdown in datepicker? |
| change_year | Show a year dropdown in datepicker? |
| first_day | First day of the week. 0 == Sunday. |
| format | The format to use for dates. Valid values are dmy, mdy, and ymd. |
| match_request | Additional request paths to match (use input class="datepick") |
| milestone | Use datepicker for milestone due/completed fields?
If you turn this on, you must use MM/DD/YYYY for the date format.
Set format to mdy and separator to / (default=Off) |
| months | Number of months visible in datepicker |
| panel | Show button panel at bottom? (Today, Done) |
| separator | The separator character to use for dates. |
| weeknumbers | Show ISO8601 week number in calendar? |
[fivestarvote]
| paths | List of URL paths to allow voting on. Globs are supported. |
[graphviz]
| cache_dir | The directory that will be used to cache the generated images.
Note that if different than the default (gvcache), this directory must
exist.
If not given as an absolute path, the path will be relative to
the Trac environment's directory. |
| cache_manager | If this entry exists and set to true in the configuration file,
then the cache management logic will be invoked
and the cache_max_size, cache_min_size,
cache_max_count and cache_min_count must be
defined. |
| cache_max_count | The maximum number of files that the cache should
contain. This is the high watermark for the
directory entry count. |
| cache_max_size | The maximum size in bytes that the cache should
consume. This is the high watermark for disk space
used. |
| cache_min_count | The minimum number of files that the cache should
contain. This is the low watermark for the
directory entry count. |
| cache_min_size | When cleaning out the cache, remove files until
this size in bytes is used by the cache. This is
the low watermark for disk space used. |
| cmd_path | Full path to the directory where the graphviz
programs are located. If not specified, the
default is /usr/bin on Linux,
C:\Program Files\ATT\Graphviz\bin on Windows and
/usr/local/bin on FreeBSD 6. |
| default_graph_dpi | Default dpi setting for graphviz, used during SVG to PNG
rasterization. |
| encoding | The encoding which should be used for communicating with
Graphviz (should match -Gcharset if given). |
| out_format | Graph output format. Valid formats are: png, jpg,
svg, svgz, gif. If not specified, the default is
png. This setting can be overrided on a per-graph
basis. |
| png_antialias | If this entry exists in the configuration file,
then PNG outputs will be antialiased.
Note that this requires rsvg to be installed. |
| processor | Graphviz default processor. Valid processors
are: dot, neato, twopi, fdp, circo. If not
specified, the default is dot. This setting can
be overrided on a per-graph basis.
GraphvizMacro will verify that the default
processor is installed and will not work if it
is missing. All other processors are optional.
If any of the other processors are missing, a
warning message will be sent to the trac log and
GraphvizMacro will continue to work. |
| rsvg_path | Full path to the rsvg program (including the filename).
The default is <cmd_path>/rsvg. |
| alt | Alternative text for the header logo. |
| height | Height of the header logo image in pixels. |
| link | URL to link to from header logo. |
| src | URL of the image to use as header logo. |
| width | Width of the header logo image in pixels. |
[httpauth]
| formats | Request formats to force HTTP authentication on |
| paths | Paths to force HTTP authentication on. |
[inherit]
| plugins_dir | Path of the directory containing additional plugins.
Plugins in that directory are loaded in addition to those in the
directory of the environment plugins, with this one taking
precedence.
(since 0.11) |
| templates_dir | Path to the shared templates directory.
Templates in that directory are loaded in addition to those in the
environments templates directory, but the latter take precedence.
(since 0.11) |
[logging]
| log_file | If log_type is file, this should be a path to the log-file. |
| log_format | Custom logging format.
If nothing is set, the following will be used:
Trac[$(module)s] $(levelname)s: $(message)s
In addition to regular key names supported by the Python logger library
library (see http://docs.python.org/lib/node422.html), one could use:
- $(path)s the path for the current environment
- $(basename)s the last path component of the current environment
- $(project)s the project name
Note the usage of $(...)s instead of %(...)s as the latter form
would be interpreted by the ConfigParser? itself.
Example:
($(thread)d) Trac[$(basename)s:$(module)s] $(levelname)s: $(message)s
(since 0.10.5) |
| log_level | Level of verbosity in log.
Should be one of (CRITICAL, ERROR, WARN, INFO, DEBUG). |
| log_type | Logging facility to use.
Should be one of (none, file, stderr, syslog, winlog). |
[milestone]
| stats_provider | Name of the component implementing ITicketGroupStatsProvider,
which is used to collect statistics on groups of tickets for display
in the milestone views. |
[mimeviewer]
| enscript_modes | List of additional MIME types known by Enscript.
For each, a tuple mimetype:mode:quality has to be
specified, where mimetype is the MIME type,
mode is the corresponding Enscript mode to be used
for the conversion and quality is the quality ratio
associated to this conversion.
That can also be used to override the default
quality ratio used by the Enscript render, which is 2
(since 0.10). |
| enscript_path | Path to the Enscript executable. |
| max_preview_size | Maximum file size for HTML preview. (since 0.9). |
| mime_map | List of additional MIME types and keyword mappings.
Mappings are comma-separated, and for each MIME type,
there's a colon (":") separated list of associated keywords
or file extensions. (since 0.10). |
| php_path | Path to the PHP executable (since 0.9). |
| pygments_default_style | The default style to use for Pygments syntax highlighting. |
| pygments_modes | List of additional MIME types known by Pygments.
For each, a tuple mimetype:mode:quality has to be
specified, where mimetype is the MIME type,
mode is the corresponding Pygments mode to be used
for the conversion and quality is the quality ratio
associated to this conversion. That can also be used
to override the default quality ratio used by the
Pygments render. |
| tab_width | Displayed tab width in file preview (since 0.9). |
[notification]
| admit_domains | Comma-separated list of domains that should be considered as
valid for email addresses (such as localdomain) |
| always_notify_owner | Always send notifications to the ticket owner (since 0.9). |
| always_notify_reporter | Always send notifications to any address in the reporter
field. |
| always_notify_updater | Always send notifications to the person who causes the ticket
property change. |
| ignore_domains | Comma-separated list of domains that should not be considered
part of email addresses (for usernames with Kerberos domains) |
| mime_encoding | Specifies the MIME encoding scheme for emails.
Valid options are 'base64' for Base64 encoding, 'qp' for
Quoted-Printable, and 'none' for no encoding. Note that the no encoding
means that non-ASCII characters in text are going to cause problems
with notifications (since 0.10). |
| notify_on_failed_build | Notify if bitten build fails. |
| notify_on_successful_build | Notify if bitten build succeeds. |
| smtp_always_bcc | Email address(es) to always send notifications to,
addresses do not appear publicly (Bcc:). (since 0.10). |
| smtp_always_cc | Email address(es) to always send notifications to,
addresses can be seen by all recipients (Cc:). |
| smtp_default_domain | Default host/domain to append to address that do not specify one |
| smtp_enabled | Enable SMTP (email) notification. |
| smtp_from | Sender address to use in notification emails. |
| smtp_from_name | Sender name to use in notification emails. |
| smtp_password | Password for SMTP server. (since 0.9). |
| smtp_port | SMTP server port to use for email notification. |
| smtp_replyto | Reply-To address to use in notification emails. |
| smtp_server | SMTP server hostname to use for email notifications. |
| smtp_subject_prefix | Text to prepend to subject line of notification emails.
If the setting is not defined, then the [$project_name] prefix.
If no prefix is desired, then specifying an empty option
will disable it.(since 0.10.1). |
| smtp_user | Username for SMTP server. (since 0.9). |
| ticket_subject_template | A Genshi text template snippet used to get the notification subject.
(since 0.11) |
| use_public_cc | Recipients can see email addresses of other CC'ed recipients.
If this option is disabled (the default), recipients are put on BCC
(since 0.10). |
| use_short_addr | Permit email address without a host/domain (i.e. username only)
The SMTP server should accept those addresses, and either append
a FQDN or use local delivery (since 0.10). |
| use_tls | Use SSL/TLS to send notifications (since 0.10). |
[openid]
| absolute_trust_root | Whether we should use absolute trust root or by project. |
| black_list | Comma separated list of denied OpenId? addresses. |
| check_list | JSON service for openid check. |
| check_list_key | Key for openid Service. |
| custom_provider_image | Custom OpenId? provider image. |
| custom_provider_label | Custom OpenId? provider label. |
| custom_provider_name | Custom OpenId? provider name. |
| custom_provider_url | Custom OpenId? provider URL. E.g.: http://claimid.com/{username} |
| default_openid | Default OpenID provider for directed identity. |
| pape_method | Default PAPE method to request from OpenID provider. |
| signup | Signup link |
| sreg_required | Whether SREG data should be required or optional. |
| strip_protocol | Instead of using username beginning with http:// or https:// you can strip the beginning. |
| strip_trailing_slash | In case your OpenID is some sub-domain address OpenId? library adds trailing slash. This option strips it. |
| timeout | Specify if expiration time should act as timeout. |
| whatis | What is OpenId? link. |
| white_list | Comma separated list of allowed OpenId? addresses. |
[project]
| admin | E-Mail address of the project's administrator. |
| descr | Short description of the project. |
| footer | Page footer text (right-aligned). |
| icon | URL of the icon of the project. |
| name | Name of the project. |
| url | URL of the main project web site, usually the website in which
the base_url resides. |
[query]
| default_anonymous_query | The default query for anonymous users. |
| default_query | The default query for authenticated users. |
| items_per_page | Number of tickets displayed per page in ticket queries,
by default (since 0.11) |
[report]
| items_per_page | Number of tickets displayed per page in ticket reports,
by default (since 0.11) |
| items_per_page_rss | Number of tickets displayed in the rss feeds for reports
(since 0.11) |
[revisionlog]
| default_log_limit | Default value for the limit argument in the TracRevisionLog
(since 0.11). |
[revtree]
| abstime | Timeline filters start on absolute time or on the youngest
revision. |
| branch_re | Regular expression to extract branches from paths |
| contexts | Navigation contexts where the Revtree item appears.
If empty, the Revtree item appears in the main navigation
bar. |
| optimizer | Name of the component implementing IRevtreeOptimizer, which is
used for optimizing revtree element placements. |
| revbase | Oldest revision to consider (older revisions are ignored) |
| scale | Default rendering scale for the SVG graph |
| style | Revtree style, 'compact' or 'timeline' |
| trunks | Branches that are considered as trunks |
[roadmap]
| stats_provider | Name of the component implementing ITicketGroupStatsProvider,
which is used to collect statistics on groups of tickets for display
in the roadmap views. |
[search]
| min_query_length | Minimum length of query string allowed when performing a search. |
[spam-filter]
| akismet_api_key | Wordpress key required to use the Akismet API. |
| akismet_api_url | URL of the Akismet service. |
| akismet_karma | By how many points an Akismet reject impacts the overall karma of
a submission. |
| attachment_sample_size | The number of bytes from an attachment to pass through the spam
filters. |
| extlinks_karma | By how many points too many external links in a submission impact
the overall score. |
| ip_throttle_karma | By how many points exceeding the configured maximum number of posts
per hour impacts the overall score. |
| logging_enabled | Whether all content submissions and spam filtering activity should
be logged to the database. |
| max_external_links | The maximum number of external links allowed in a submission until
that submission gets negative karma. |
| max_posts_by_ip | The maximum allowed number of submissions per hour form a single IP
address. If this limit is exceeded, subsequent permissions get negative
karma. |
| min_karma | The minimum score required for a submission to be allowed. |
| purge_age | The number of days after which log entries should be purged. |
| regex_karma | By how many points a match with a pattern on the BadContent? page
impacts the overall karma of a submission. |
| session_karma | By how many points an existing and configured session improves the
overall karma of the submission. A third of the points is granted for
having an existing session at all, the other two thirds are granted
when the user has his name and/or email address set in the session,
respectively. |
| trust_authenticated | Whether content submissions by authenticated users should be trusted
without checking for potential spam or other abuse. |
[svn]
| branches | List of paths categorized as branches.
If a path ends with '*', then all the directory entries found
below that path will be included. |
| tags | List of paths categorized as tags.
If a path ends with '*', then all the directory entries found
below that path will be included. |
[ticket]
| default_component | Default component for newly created tickets |
| default_milestone | Default milestone for newly created tickets. |
| default_priority | Default priority for newly created tickets. |
| default_resolution | Default resolution for resolving (closing) tickets
(since 0.11). |
| default_type | Default type for newly created tickets (since 0.9). |
| default_version | Default version for newly created tickets. |
| max_description_size | Don't accept tickets with a too big description.
(since 0.11). |
| preserve_newlines | Whether Wiki formatter should respect the new lines present
in the Wiki text.
If set to 'default', this is equivalent to 'yes' for new environments
but keeps the old behavior for upgraded environments (i.e. 'no').
(since 0.11). |
| restrict_owner | Make the owner field of tickets use a drop-down menu. See
Assign-to as Drop-Down List
(since 0.9). |
| workflow | Ordered list of workflow controllers to use for ticket actions
(since 0.11). |
[ticketstats]
| default_days_back | Number of days to show by default |
| default_interval | Number of days between each data point (resolution) by default |
| yui_base_url | Location of YUI API |
[timeline]
| abbreviated_messages | Whether wiki-formatted event messages should be truncated or not.
This only affects the default rendering, and can be overriden by
specific event providers, see their own documentation.
(Since 0.11) |
| changeset_collapse_events | Whether consecutive changesets from the same author having
exactly the same message should be presented as one event.
That event will link to the range of changesets in the log view.
(since 0.11) |
| changeset_long_messages | Whether wiki-formatted changeset messages should be multiline or not.
If this option is not specified or is false and wiki_format_messages
is set to true, changeset messages will be single line only, losing
some formatting (bullet points, etc). |
| changeset_show_files | Number of files to show (-1 for unlimited, 0 to disable).
This can also be location, for showing the common prefix for the
changed files. (since 0.11). |
| default_daysback | Default number of days displayed in the Timeline, in days.
(since 0.9.) |
| max_daysback | Maximum number of days (-1 for unlimited) displayable in the
Timeline. (since 0.11) |
| newticket_formatter | Which formatter flavor (e.g. 'default' or 'oneliner') should be
used when presenting the description for new tickets.
If 'oneliner', the [timeline] abbreviated_messages option applies.
(since 0.11). |
| ticket_show_details | Enable the display of all ticket changes in the timeline
(since 0.9). |
[trac]
| authz_file | Path to Subversion
authorization (authz) file |
| authz_module_name | The module prefix used in the authz_file. |
| auto_reload | Automatically reload template files after modification. |
| base_url | Reference URL for the Trac deployment.
This is the base URL that will be used when producing documents that
will be used outside of the web browsing context, like for example
when inserting URLs pointing to Trac resources in notification
e-mails. |
| check_auth_ip | Whether the IP address of the user should be checked for
authentication (since 0.9). |
| check_auth_ip_mask | What mask should be applied to user address. |
| database | Database connection
string for this
project |
| default_charset | Charset to be used when in doubt. |
| default_handler | Name of the component that handles requests to the base URL.
Options include TimelineModule, RoadmapModule, BrowserModule,
QueryModule, ReportModule and TicketModule (since 0.9). |
| default_timezone | The default timezone to use |
| expires | Specify how fast authentication expires. |
| htdocs_location | Base URL of the core static resources. |
| ignore_auth_case | Whether login names should be converted to lower case
(since 0.9). |
| mainnav | Order of the items to display in the mainnav navigation bar,
listed by IDs. See also TracNavigation. |
| metanav | Order of the items to display in the metanav navigation bar,
listed by IDs. See also TracNavigation. |
| permission_policies | List of components implementing IPermissionPolicy, in the order in
which they will be applied. These components manage fine-grained access
control to Trac resources.
Defaults to the DefaultPermissionPolicy? (pre-0.11 behavior) and
LegacyAttachmentPolicy? (map ATTACHMENT_* permissions to realm specific
ones) |
| permission_store | Name of the component implementing IPermissionStore, which is used
for managing user and group permissions. |
| repository_dir | Path to local repository. This can also be a relative path
(since 0.11). |
| repository_type | Repository connector type. (since 0.10) |
| request_filters | Ordered list of filters to apply to all requests
(since 0.10). |
| show_email_addresses | Show email addresses instead of usernames. If false, we obfuscate
email addresses (since 0.11). |
| timeout | Timeout value for database connection, in seconds.
Use '0' to specify no timeout. (Since 0.11) |
| use_base_url_for_redirect | Optionally use [trac] base_url for redirects.
In some configurations, usually involving running Trac behind a HTTP
proxy, Trac can't automatically reconstruct the URL that is used to
access it. You may need to use this option to force Trac to use the
base_url setting also for redirects. This introduces the obvious
limitation that this environment will only be usable when accessible
from that URL, as redirects are frequently used. (since 0.10.5) |
[tracwysiwyg]
| wysiwyg_stylesheets | Add stylesheets to the WYSIWYG editor |
[wiki]
| ignore_missing_pages | Enable/disable highlighting CamelCase links to missing pages
(since 0.9). |
| render_unsafe_content | Enable/disable the use of unsafe HTML tags such as <script> or
<embed> with the HTML WikiProcessor
(since 0.10.4).
For public sites where anonymous users can edit the wiki it is
recommended to leave this option disabled (which is the default). |
| split_page_names | Enable/disable splitting the WikiPageNames with space characters
(since 0.10). |
[components]
This section is used to enable or disable components provided by plugins, as well as by Trac itself. The component to enable/disable is specified via the name of the option. Whether its enabled is determined by the option value; setting the value to enabled or on will enable the component, any other value (typically disabled or off) will disable the component.
The option name is either the fully qualified name of the components or the module/package prefix of the component. The former enables/disables a specific component, while the latter enables/disables any component in the specified package/module.
Consider the following configuration snippet:
[components]
trac.ticket.report.ReportModule = disabled
webadmin.* = enabled
The first option tells Trac to disable the report module. The second option instructs Trac to enable all components in the webadmin package. Note that the trailing wildcard is required for module/package matching.
See the Plugins page on About Trac to get the list of active components (requires CONFIG_VIEW permissions.)
See also: TracPlugins
[ticket-custom]
In this section, you can define additional fields for tickets. See TracTicketsCustomFields for more details.
[ticket-workflow]
(since 0.11)
The workflow for tickets is controlled by plugins.
By default, there's only a ConfigurableTicketWorkflow component in charge.
That component allows the workflow to be configured via this section in the trac.ini file.
See TracWorkflow for more details.
[milestone-groups]
(since 0.11)
As the workflow for tickets is now configurable, there can be many ticket states,
and simply displaying closed tickets vs. all the others is maybe not appropriate
in all cases. This section enables one to easily create groups of states
that will be shown in different colors in the milestone progress bar.
Example configuration (the default only has closed and active):
closed = closed
closed.order = 0 # sequence number in the progress bar
closed.query_args = group=resolution # optional extra param for the query
closed.overall_completion = true # indicates groups that count for overall completion percentage
new = new
new.order = 1
new.css_class = new
new.label = new
active = * # one catch-all group is allowed
active.order = 1
active.css_class = open # CSS class for this interval
active.label = in progress # Displayed label for this group
The definition consists in a comma-separated list of accepted status.
Also, '*' means any status and could be used to associate all remaining
states to one catch-all group.
The CSS class can be one of: new (yellow), open (no color) or
closed (green). New styles can easily be added using the following
selector: table.progress td.<class>
[svn:externals]
(since 0.11)
The TracBrowser for Subversion can interpret the svn:externals property of folders out of the box.
However, if those externals are not using the http: protocol, or if a link to a different repository browser (such another Trac or ViewVC) is desired, then Trac needs to be able to map an external prefix to this other URL.
This mapping is done in the [svn:externals] section of the TracIni
Example:
[svn:externals]
1 = svn://server/repos1 http://trac/proj1/browser/$path?rev=$rev
2 = svn://server/repos2 http://trac/proj2/browser/$path?rev=$rev
3 = http://theirserver.org/svn/eng-soft http://ourserver/viewvc/svn/$path/?pathrev=25914
4 = svn://anotherserver.com/tools_repository http://ourserver/trac/support/browser/$path?rev=$rev
With the above, the svn://anotherserver.com/tools_repository/tags/1.1/tools external will be mapped to http://ourserver/trac/support/browser/tags/1.1/tools?rev= (and rev will be set to the appropriate revision number if the external additionally specifies a revision, see the SVN Book on externals for more details).
Note that the number used as a key in the above section is purely used as a place holder, as the URLs themselves can't be used as a key due to various limitations in the configuration file parser.
See also: TracGuide, TracAdmin, TracEnvironment
