Silent header

19.0.0 released Nov 08, 2023

Silent header

Purpose: Do not output HTTP headers.

silent-header

silent-header will suppress the output of HTTP headers, such as with out-header, or in any other case where headers are output. The effect applies to current request only; if you use it conditionally, then you can have it on or off dynamically. If you want to suppres the headers across the entire command-line application, use VV_SILENT_HEADER environment variable; see command-line.

Note that you still have to use out-header regardless, as it is expected to be there if you output anything; however its actual output will be suppressed. silent-header must be used prior to outputting headers.

There are many uses for silent-header, among them:

A command line program may use it to produce generic output, without any headers,
the output from command line program may be redirected to a web file (such as html), in case of dynamic content that rarely changes,
a web program may output a completely different (non-HTTP) set of headers, etc.

Examples

silent-header
out-header

// No headers output