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libcurl-env-dbg(3) libcurl libcurl-env-dbg(3)
NAME
libcurl-env-dbg - environment variables libcurl DEBUGBUILD understands
DESCRIPTION
This is a set of variables only recognized and used if libcurl was
built "debug enabled", which should never be true for a library used in
production. These variables are intended for internal use only,
subject to change and have many effects on the behavior of libcurl.
Refer to the source code to determine how exactly they are being used.
CURL_ALTSVC_HTTP
Bypass the AltSvc HTTPS protocol restriction if this
variable exists.
CURL_DBG_SOCK_RBLOCK
The percentage of recv() calls that should be answered
with a EAGAIN at random. For TCP/UNIX sockets.
CURL_DBG_SOCK_RMAX
The maximum data that shall be received from the network
in one recv() call. For TCP/UNIX sockets. This is
applied to every recv.
Example: CURL_DBG_SOCK_RMAX=400 means recv buffer size is
limited to a maximum of 400 bytes.
CURL_DBG_SOCK_WBLOCK
The percentage of send() calls that should be answered
with a EAGAIN at random. For TCP/UNIX sockets.
CURL_DBG_SOCK_WPARTIAL
The percentage of data that shall be written to the
network. For TCP/UNIX sockets. This is applied to every
send.
Example: CURL_DBG_SOCK_WPARTIAL=80 means a send with 1000
bytes would only send 800.
CURL_DBG_QUIC_WBLOCK
The percentage of send() calls that should be answered
with EAGAIN at random. QUIC only.
CURL_DEBUG
Trace logging behavior as an alternative to calling
curl_global_trace(3).
Example: CURL_DEBUG=http/2 means trace details about
HTTP/2 handling.
CURL_DEBUG_SIZE
Fake the size returned by CURLINFO_HEADER_SIZE and
CURLINFO_REQUEST_SIZE.
CURL_GETHOSTNAME
Fake the local machine's unqualified hostname for NTLM
A time of 0 is used for AWS signatures and NTLM if this
variable exists.
CURL_ENTROPY
A fixed faked value to use instead of a proper random
number so that functions in libcurl that are otherwise
getting random outputs can be tested for what they
generate.
CURL_SMALLREQSEND
An alternative size of HTTP data to be sent at a time
only if smaller than the current.
CURL_SMALLSENDS
An alternative size of socket data to be sent at a time
only if smaller than the current.
CURL_TIME
Fake unix timestamp to use for AltSvc, HSTS and CURLINFO
variables that are time related.
This variable can also be used to fake the data returned
by some CURLINFO variables that are not time-related
(such as CURLINFO_LOCAL_PORT), and in that case the value
is not a timestamp.
CURL_TRACE
LDAP tracing is enabled if this variable exists and its
value is 1 or greater.
OpenLDAP tracing is separate. Refer to
CURL_OPENLDAP_TRACE.
CURL_NTLM_WB_FILE
Debug-version of the ntlm-wb executable.
CURL_OPENLDAP_TRACE
OpenLDAP tracing is enabled if this variable exists and
its value is 1 or greater. There's a number of debug
levels, refer to openldap.c comments.
SEE ALSO
libcurl-env(3)
libcurl 8.5.0 September 7, 2023 libcurl-env-dbg(3)