noble (3) libcurl-env.3.gz

NAME

       libcurl-env - environment variables libcurl understands

DESCRIPTION

       libcurl  reads and understands a set of environment variables that if set controls and changes behaviors.
       This is the full list of variables to set and description of what they  do.  Also  note  that  curl,  the
       command line tool, supports a set of additional environment variables independently of this.

              [scheme]_proxy
                     When  libcurl  is  given a URL to use in a transfer, it first extracts the scheme part from
                     the URL and checks if there is a given proxy set for that in its corresponding  environment
                     variable. A URL like https://example.com makes libcurl use the http_proxy variable, while a
                     URL like ftp://example.com uses the ftp_proxy variable.

                     These proxy variables are  also  checked  for  in  their  uppercase  versions,  except  the
                     http_proxy  one  which  is only used lowercase. Note also that some systems actually have a
                     case insensitive handling of environment variables and  then  of  course  HTTP_PROXY  still
                     works.

                     An  exception  exists  for the WebSocket ws and wss URL schemes, where libcurl first checks
                     ws_proxy or wss_proxy but if they are not set, it will fall back and try the http and https
                     versions instead if set.

              ALL_PROXY
                     This  is  a  setting to set proxy for all URLs, independently of what scheme is being used.
                     Note that the scheme specific variables overrides this one if set.

              CURL_SSL_BACKEND
                     When libcurl is built to support multiple SSL backends, it selects a  specific  backend  at
                     first  use. If no selection is done by the program using libcurl, this variable's selection
                     is used. Setting a name that is not a built-in alternative  makes  libcurl  stay  with  the
                     default.

                     SSL  backend  names  (case-insensitive):  BearSSL,  GnuTLS,  mbedTLS, nss, OpenSSL, rustls,
                     Schannel, Secure-Transport, wolfSSL

              HOME   When the netrc feature is used (CURLOPT_NETRC(3)), this variable is checked as the  primary
                     way to find the "current" home directory in which the .netrc file is likely to exist.

              USERPROFILE
                     When  the  netrc  feature  is  used  (CURLOPT_NETRC(3)),  this  variable  is checked as the
                     secondary way to find the "current" home directory (on Windows only) in  which  the  .netrc
                     file is likely to exist.

              LOGNAME
                     User name to use when invoking the ntlm-wb tool, if NTLMUSER was not set.

              NO_PROXY
                     This has the same functionality as the CURLOPT_NOPROXY(3) option: it gives libcurl a comma-
                     separated list of host name patterns for which libcurl should not use a proxy.

              NTLMUSER
                     User name to use when invoking the ntlm-wb tool.

              SSLKEYLOGFILE
                     When set and libcurl runs with a SSL backend that supports this feature, libcurl saves  SSL
                     secrets  into the given file name. Using those SSL secrets, other tools (such as Wireshark)
                     can decrypt the SSL communication and analyze/view the traffic.

                     These secrets and this file might be sensitive. Users are advised to  take  precautions  so
                     that they are not stolen or otherwise inadvertently revealed.

              USER   User name to use when invoking the ntlm-wb tool, if NTLMUSER and LOGNAME were not set.

Debug Variables

       Debug variables are intended for internal use and are documented in libcurl-env-dbg(3).

SEE ALSO

       libcurl-env-dbg(3)