= Trac Links =
[[TracGuideToc]]

TracLinks are a fundamental feature of Trac, because they allow easy hyperlinking between the various entities in the system—such as tickets, reports, changesets, Wiki pages, milestones, and source files—from anywhere WikiFormatting is used.

TracLinks are generally of the form '''type:id''' (where ''id'' represents the
number, name or path of the item) though some frequently used kinds of items
also have short-hand notations.

== Where to use TracLinks ==
You can use TracLinks in:

 * Source code (Subversion) commit messages
 * Wiki pages
 * Full descriptions for tickets, reports and milestones

and any other text fields explicitly marked as supporting WikiFormatting.

Some examples:
 * Tickets: '''!#1''' or '''!ticket:1'''
 * Ticket comments: '''!comment:1:ticket:2''' 
 * Reports: '''!{1}''' or '''!report:1'''
 * Changesets: '''!r1''', '''![1]''', '''!changeset:1''' or (restricted) '''![1/trunk]''', '''!changeset:1/trunk'''
 * Revision log: '''!r1:3''', '''![1:3]''' or '''!log:@1:3''', '''!log:trunk@1:3''', '''![2:5/trunk]'''
 * Diffs (requires [trac:milestone:0.10 0.10]): '''!diff:@1:3''', '''!diff:tags/trac-0.9.2/wiki-default//tags/trac-0.9.3/wiki-default''' or '''!diff:trunk/trac@3538//sandbox/vc-refactoring@3539'''
 * Wiki pages: '''!CamelCase''' or '''!wiki:CamelCase'''
 * Parent page: '''![..]'''
 * Milestones: '''!milestone:1.0'''
 * Attachment: '''!attachment:example.tgz''' (for current page attachment), '''!attachment:attachment.1073.diff:ticket:944''' 
(absolute path)
 * Files: '''!source:trunk/COPYING'''
 * A specific file revision: '''!source:/trunk/COPYING@200'''
 * A particular line of a specific file revision: '''!source:/trunk/COPYING@200#L25'''
Display:
 * Tickets: #1 or ticket:1
 * Ticket comments: comment:1:ticket:2 
 * Reports: {1} or report:1
 * Changesets: r1, [1], changeset:1 or (restricted) [1/trunk], changeset:1/trunk
 * Revision log: r1:3, [1:3] or log:@1:3, log:trunk@1:3, [2:5/trunk]
 * Diffs (requires [milestone:0.10 0.10]): diff:@1:3, diff:tags/trac-0.9.2/wiki-default//tags/trac-0.9.3/wiki-default or diff:trunk/trac@3538//sandbox/vc-refactoring@3539
 * Wiki pages: CamelCase or wiki:CamelCase
 * Parent page: [..]
 * Milestones: milestone:1.0
 * Attachment: attachment:example.tgz (for current page attachment), attachment:attachment.1073.diff:ticket:944 
(absolute path)
 * Files: source:trunk/COPYING
 * A specific file revision: source:/trunk/COPYING@200
 * A particular line of a specific file revision: source:/trunk/COPYING@200#L25

'''Note:''' The wiki:CamelCase form is rarely used, but it can be convenient to refer to
pages whose names do not follow WikiPageNames rules, i.e., single words,
non-alphabetic characters, etc. See WikiPageNames for more about features specific
to links to Wiki page names.

Trac links using the full (non-shorthand) notation can also be given a custom
link title like this:

{{{
[ticket:1 This is a link to ticket number one].
}}}

Display: [ticket:1 This is a link to ticket number one].

If the title is omitted, only the id (the part after the colon) is displayed:

{{{
[ticket:1]
}}}

Display: [ticket:1]

`wiki` is the default if the namespace part of a full link is omitted (''since version 0.10''):

{{{
[SandBox the sandbox]
}}}

Display: [SandBox the sandbox]

TracLinks are a very simple idea, but actually allow quite a complex network of information. In practice, it's very intuitive and simple to use, and we've found the "link trail" extremely helpful to better understand what's happening in a project or why a particular change was made.


== Advanced use of TracLinks ==

=== Relative links ===

To create a link to a specific anchor in a page, use '#':
{{{
 [#Relativelinks relative links]
}}}
Displays:
  [#Relativelinks relative links]

Hint: when you move your mouse over the title of a section, a '¶' character will be displayed. This is a link to that specific section and you can use this to copy the `#...` part inside a relative link to an anchor.

To create a link to a [trac:SubWiki SubWiki]-page just use a '/':
{{{
 WikiPage/SubWikiPage or ./SubWikiPage
}}}

To link from a [trac:SubWiki SubWiki] page to a parent, simply use a '..':
{{{
  [..]
}}}

To link from a [trac:SubWiki SubWiki] page to a sibling page, use a '../':
{{{
  [../Sibling see next sibling]
}}}

''(Changed in 0.11)'' Note that in Trac 0.10, using e.g. `[../newticket]`  may have worked for linking to the /newticket top-level URL, but now in 0.11 it will stay in the wiki namespace and link to a sibling page. See [#Server-relativelinks] for the new syntax.

=== InterWiki links ===

Other prefixes can be defined freely and made to point to resources in other Web applications. The definition of those prefixes as well as the URLs of the corresponding Web applications is defined in a special Wiki page, the InterMapTxt page. Note that while this could be used to create links to other Trac environments, there's a more specialized way to register other Trac environments which offers greater flexibility.

=== InterTrac links ===

This can be seen as a kind of InterWiki link specialized for targeting other Trac projects.

Any type of Trac links could be written in one Trac environment and actually refer to resources present in another Trac environment, provided the Trac link is prefixed by the name of that other Trac environment followed by a colon. That other Trac environment must be registered, under its name or an alias. See InterTrac for details. 

A distinctive advantage of InterTrac links over InterWiki links is that the shorthand form of Trac links usually have a way to understand the InterTrac prefixes. For example, links to Trac tickets can be written #T234 (if T was set as an alias for Trac), links to Trac changesets can be written [trac 1508].

=== Server-relative links ===

It is often useful to be able to link to objects in your project that
have no built-in Trac linking mechanism, such as static resources, `newticket`,
a shared `/register` page on the server, etc.

To link to resources inside the project, use either an absolute path from the project root, 
or a relative link from the URL of the current page (''Changed in 0.11''):

{{{
[/newticket Create a new ticket]
[/ home]
}}}

Display: [/newticket newticket] [/ home]

To link to another location on the server (outside the project), use the '//location' link syntax (''Changed in 0.11''):

{{{
[//register Register Here]
}}}

Display: [//register Register Here]

=== Quoting space in TracLinks ===

Immediately after a TracLinks prefix, targets containing space characters should
be enclosed in a pair of quotes or double quotes.
Examples:
 * !wiki:"The whitespace convention"
 * !attachment:'the file.txt' or
 * !attachment:"the file.txt" 
 * !attachment:"the file.txt:ticket:123" 

=== Escaping Links ===

To prevent parsing of a !TracLink, you can escape it by preceding it with a '!' (exclamation mark).
{{{
 !NoLinkHere.
 ![42] is not a link either.
}}}

Display:
 !NoLinkHere.
 ![42] is not a link either.


=== Parameterized Trac links ===

The Trac links target Trac resources which have generally more than one way to be rendered, according to some extra parameters. For example, a Wiki page can accept a `version` or a `format` parameter, a report can make use of dynamic variables, etc.

Any Trac links can support an arbitrary set of parameters, written in the same way as they would be for the corresponding URL. Some examples:
 - `wiki:WikiStart?format=txt`
 - `ticket:1?version=1`
 - `[/newticket?component=module1 create a ticket for module1]`


== TracLinks Reference ==
The following sections describe the individual link types in detail, as well as several notes advanced usage of links.

=== attachment: links ===

The link syntax for attachments is as follows:
 * !attachment:the_file.txt creates a link to the attachment the_file.txt of the current object
 * !attachment:the_file.txt:wiki:MyPage creates a link to the attachment the_file.txt of the !MyPage wiki page
 * !attachment:the_file.txt:ticket:753 creates a link to the attachment the_file.txt of the ticket 753

Note that the older way, putting the filename at the end, is still supported: !attachment:ticket:753:the_file.txt.

If you'd like to create a direct link to the content of the attached file instead of a link to the attachment page, simply use `raw-attachment:` instead of `attachment:`.

This can be useful for pointing directly to an HTML document, for example. Note that for this use case, you'd have to allow the web browser to render the content by setting `[attachment] render_unsafe_content = yes` (see TracIni#attachment-section). Caveat: only do that in environments for which you're 100% confident you can trust the people who are able to attach files, as otherwise this would open up your site to [wikipedia:Cross-site_scripting cross-site scripting] attacks.

See also [#export:links].

=== comment: links ===

When you're inside a given tickets, you can simply write e.g. !comment:3 to link to the third change comment.
It's also possible to link to a comment of a specific ticket from anywhere using one of the following syntax:
 - !comment:3:ticket:123 
 - !ticket:123#comment:3 (note that you can't write !#123#!comment:3!)

=== query: links ===

See TracQuery#UsingTracLinks and [#ticket:links].

=== search: links ===

See TracSearch#SearchLinks 

=== ticket: links ===

Besides the obvious `ticket:id` form, it is also possible to specify a list of tickets or even a range of tickets instead of the `id`. This generates a link to a custom query view containing this fixed set of tickets.

Example: 
 - `ticket:5000-6000`
 - `ticket:1,150`

''(since Trac 0.11)''

=== timeline: links ===

Links to the timeline can be created by specifying a date in the ISO:8601 format. The date can be optionally followed by a time specification. The time is interpreted as being UTC time, but alternatively you can specify your local time, followed by your timezone if you don't want to compute the UTC time.

Examples:
 - `timeline:2008-01-29`
 - `timeline:2008-01-29T15:48`
 - `timeline:2008-01-29T16:48Z+01`

''(since Trac 0.11)''

=== wiki: links ===

See WikiPageNames and [#QuotingspaceinTracLinks quoting space in TracLinks] above.

=== Version Control related links ===
==== source: links ====

The default behavior for a source:/some/path link is to open the directory browser 
if the path points to a directory and otherwise open the log view.

It's also possible to link directly to a specific revision of a file like this:
 - `source:/some/file@123` - link to the file's revision 123
 - `source:/some/file@head` - link explicitly to the latest revision of the file

If the revision is specified, one can even link to a specific line number:
 - `source:/some/file@123#L10`
 - `source:/tag/0.10@head#L10`

Finally, one can also highlight an arbitrary set of lines:
 - `source:/some/file@123:10-20,100,103#L99` - highlight lines 10 to 20, and lines 100 and 103.
''(since 0.11)''

==== export: links ====

To force the download of a file in the repository, as opposed to displaying it in the browser, use the `export` link.  Several forms are available:
 * `export:/some/file` - get the HEAD revision of the specified file
 * `export:123:/some/file` - get revision 123 of the specified file
 * `export:/some/file@123` - get revision 123 of the specified file

This can be very useful for displaying XML or HTML documentation with correct stylesheets and images, in case that has been checked in into the repository. Note that for this use case, you'd have to allow the web browser to render the content by setting `[browser] render_unsafe_content = yes` (see TracIni#browser-section), otherwise Trac will force the files to be downloaded as attachments for security concerns. 

If the path is to a directory in the repository instead of a specific file, the source browser will be used to display the directory (identical to the result of `source:/some/dir`).

==== log: links ====

The `log:` links are used to display revision ranges. In its simplest form, it can link to the latest revisions from the specified path, but it can also support displaying an arbitrary set of revisions.
 - `log:/` - the latest revisions starting at the root of the repository
 - `log:/trunk/tools` - the latest revisions in `trunk/tools`
 - `log:/trunk/tools@10000` - the revisions in `trunk/tools` starting from  revision 10000
 - `log:@20788,20791:20795` - list revision 20788 and the 20791 to 20795 revision range
 - `log:/trunk/tools@20788,20791:20795` - list revision 20788 and the revisions from the 20791 to 20795 range which affect the given path

There are short forms for revision ranges as well:
 - `[20788,20791:20795]`
 - `[20788,20791:20795/trunk/tools]`
 - `r20791:20795` (but not `r20788,20791:20795` nor `r20791:20795/trunk`)

Finally, note that in all of the above, a revision range can be written indifferently `x:y` or `x-y`.

----
See also: WikiFormatting, TracWiki, WikiPageNames, InterTrac, InterWiki
 
