Start the Dynamic HTML Help System

Description

This function starts the internal help server, so that HTML help pages are rendered when requested.

Usage

startDynamicHelp(start = TRUE)

Arguments

Details

This function starts the internal HTTP server, which runs on the loopback interface (‘⁠127.0.0.1⁠’). If options("help.ports") is set to a vector of non-zero integer values, startDynamicHelp will try those ports in order; otherwise, it tries up to 10 random ports to find one not in use. It can be disabled by setting the environment variable R_DISABLE_HTTPD to a non-empty value or options("help.ports") to 0.

startDynamicHelp is called by functions that need to use the server, so would rarely be called directly by a user.

Note that options(help_type = "html") must be set to actually make use of HTML help, although it might be the default for an R installation.

If the server cannot be started or is disabled, help.start will be unavailable and requests for HTML help will give text help (with a warning).

The browser in use does need to be able to connect to the loopback interface: occasionally it is set to use a proxy for HTTP on all interfaces, which will not work – the solution is to add an exception for ‘⁠127.0.0.1⁠’.

Value

The chosen port number is returned invisibly (which will be 0 if the server has been stopped).

See Also

help.start and help(help_type = "html") will attempt to start the HTTP server if required

Rd2HTML is used to render the package help pages.