[#OSSL_trace_begin]
= OSSL_trace_begin
:mrdocs:

Begin a locked trace output group for `category` and return its BIO channel.

== Synopsis

Declared in `<openssl/trace.h>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
xref:BIO.adoc[BIO]*
OSSL_trace_begin(int category);
----

== Description

Pair with OSSL_trace_end() using the same category and returned BIO.

== Return Value

Trace BIO to write to, or NULL if tracing is disabled for `category.`

== Parameters

[cols="1,4"]
|===
| Name| Description
| *category*
| OSSL_TRACE_CATEGORY_* value selecting the channel.
|===


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