1libcurl-env(3)           libcurl environment variables          libcurl-env(3)
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NAME

6       libcurl-env - environment variables libcurl understands
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DESCRIPTION

9       libcurl  reads  and  understands a set of environment variables that if
10       set will control and change behaviors. This is the full list  of  vari‐
11       ables  to set and description of what they do. Also note that curl, the
12       command line tool, supports a set of additional  environment  variables
13       independently of this.
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15       [scheme]_proxy
16              When  libcurl  is  given  a  URL  to use in a transfer, it first
17              extracts the "scheme" part from the URL and checks if there is a
18              given  proxy set for that in its corresponding environment vari‐
19              able.  A  URL  like  "http://example.com"  will  hence  use  the
20              "http_proxy" variable, while a URL like "ftp://example.com" will
21              use the "ftp_proxy" variable.
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23              These proxy variables are also checked for  in  their  uppercase
24              versions,  except the "http_proxy" one which is only used lower‐
25              case. Note also that some systems actually have a case  insensi‐
26              tive  handling  of  environment  variables  and  then  of course
27              "HTTP_PROXY" will still work...
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29       ALL_PROXY
30              This is a setting to set proxy for all  URLs,  independently  of
31              what  scheme  is being used. Note that the scheme specific vari‐
32              ables will override this one if set.
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34       CURL_SSL_BACKEND
35              When libcurl is built to support multiple SSL backends, it  will
36              select  a specific backend at first use. If no selection is done
37              by the program using libcurl, this variable's selection will  be
38              used. It should be set to the full SSL backend name to use (case
39              insensitive).
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41       HOME   When the netrc feature is used (CURLOPT_NETRC(3)), this variable
42              is  checked as the primary way to find the "current" home direc‐
43              tory in which the .netrc file is likely to exist.
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45       LOGNAME
46              User name to use when invoking the  ntlm-wb  tool,  if  NTLMUSER
47              wasn't set.
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49       NO_PROXY
50              This  has  the  same  functionality  as  the  CURLOPT_NOPROXY(3)
51              option: it gives libcurl a comma-separated  list  of  host  name
52              patterns for which libcurl should not use a proxy.
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54       NTLMUSER
55              User name to use when invoking the ntlm-wb tool.
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57       SSLKEYLOGFILE
58              When  set and libcurl runs with a SSL backend that supports this
59              feature, libcurl will save SSL secrets into the given file name.
60              Using  those  SSL  secrets,  other tools (such as Wireshark) can
61              decrypt the SSL communication and analyze/view the traffic.
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63       SSL_DIR
64              When libcurl runs with the NSS backends for TLS  features,  this
65              variable  is  used  to  find  the directory for NSS PKI database
66              instead of the built-in.
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68       USER   User name to use when invoking the ntlm-wb tool, if NTLMUSER and
69              LOGNAME weren't set.
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Debug Variables

72       There's  a  set  of  variables  only recognized and used if libcurl was
73       built "debug enabled", which should never be true for a library used in
74       production.
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76       CURL_GETHOSTNAME
77              Debug-only variable.
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79       CURL_FORCETIME
80              Debug-only variable.
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82       CURL_ENTROPY
83              Debug-only  variable.  Used  to  set  a fixed faked value to use
84              instead of a proper random number so that functions  in  libcurl
85              that are otherwise getting random outputs can be tested for what
86              they generate.
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88       CURL_TRACE
89              Debug-only variable. Used for debugging the lib/ldap implementa‐
90              tion.
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92       CURL_NTLM_WB_FILE
93              Debug-only variable. Used to set to a debug-version of the ntlm-
94              wb executable.
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96       CURL_OPENLDAP_TRACE
97              Debug-only  variable.  Used  for  debugging  the  lib/openldap.c
98              implementation.
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102libcurl 7.69.1                  April 17, 2018                  libcurl-env(3)
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