I am displaying a value on my <single> - part of a nice and easy form search dashboard. Now I want to search by that value, so I'm setting up a drilldown.
However, when I set the linkSearch parameter to $session_id$, what is being displayed on the singlevalue, it comes through as the literal text $session_id$ on the next dashboard (set to flashtimeline via the linkView parameter).
What value do I put in linkSearch to be able to add the value of the singlevalue to the search, thus turning it into an actually useful drilldown? $value$?
There's no facility in SingleValue for dynamic searches unfortunately. You can define that 'linkSearch' parameter but it's purely static and it cant incorporate any dynamic $foo$ tokens.
However if you want to do it anyway, you can use Sideview Utils to do it. Download Sideview Utils ( http://sideviewapps.com/apps/sideview-utils/ and click 'download full version'), install it, restart Splunk, read the homepage docs and the first few pages of intro docs.
Then you can skip to "Module Reference > HTML Module > Using HTML instead of the SingleValue module."
That whole page has several living interactive examples of how you can do what you need to do. There are simple examples where there's no link, and more complex examples where the HTML module has a link to another view. In your case unless you converted the target view to Sideview Utils as well you'll want to build the link matching the normal Splunk "?q=search my search terms" convention.
For example, you would end up with this configuration: