curl(1) Curl Manual curl(1)

NAME curl - transfer a URL

SYNOPSIS curl [options] [URL...]

DESCRIPTION curl is a tool to transfer data from or to a server, using one of the supported protocols (DICT, FILE, FTP, FTPS, GOPHER, HTTP, HTTPS, IMAP, IMAPS, LDAP, LDAPS, POP3, POP3S, RTMP, RTSP, SCP, SFTP, SMB, SMBS, SMTP, SMTPS, TELNET and TFTP). The command is designed to work without user interaction.

   curl offers a busload of useful tricks like proxy support, user authen‐
   tication, FTP upload, HTTP post, SSL connections, cookies, file  trans‐
   fer  resume,  Metalink,  and more. As you will see below, the number of
   features will make your head spin!

   curl is powered by  libcurl  for  all  transfer-related  features.  See
   libcurl(3) for details.

URL The URL syntax is protocol-dependent. You'll find a detailed descrip‐ tion in RFC 3986.

   You can specify multiple URLs or parts of URLs  by  writing  part  sets
   within braces as in:

     http://site.{one,two,three}.com

   or you can get sequences of alphanumeric series by using [] as in:

     ftp://ftp.numericals.com/file[1-100].txt

     ftp://ftp.numericals.com/file[001-100].txt    (with leading zeros)

     ftp://ftp.letters.com/file[a-z].txt

   Nested  sequences  are not supported, but you can use several ones next
   to each other:

     http://any.org/archive[1996-1999]/vol[1-4]/part{a,b,c}.html

   You can specify any amount of URLs on the command line.  They  will  be
   fetched in a sequential manner in the specified order.

   You  can  specify a step counter for the ranges to get every Nth number
   or letter:

     http://www.numericals.com/file[1-100:10].txt

     http://www.letters.com/file[a-z:2].txt

   When using [] or {} sequences when invoked from a command line  prompt,
   you probably have to put the full URL within double quotes to avoid the
   shell from interfering with it. This also  goes  for  other  characters
   treated special, like for example '&', '?' and '*'.

   Provide  the IPv6 zone index in the URL with an escaped percentage sign
   and the interface name. Like in

     http://[fe80::3%25eth0]/

   If you specify URL without protocol:// prefix,  curl  will  attempt  to
   guess  what  protocol  you might want. It will then default to HTTP but
   try other protocols based on often-used host name prefixes.  For  exam‐
   ple,  for  host names starting with "ftp." curl will assume you want to
   speak FTP.

   curl will do its best to use what you pass to it as a URL.  It  is  not
   trying  to  validate it as a syntactically correct URL by any means but
   is instead very liberal with what it accepts.

   curl will attempt to re-use connections for multiple file transfers, so
   that  getting many files from the same server will not do multiple con‐
   nects / handshakes. This improves speed. Of course this is only done on
   files  specified  on  a  single command line and cannot be used between
   separate curl invokes.

PROGRESS METER curl normally displays a progress meter during operations, indicating the amount of transferred data, transfer speeds and estimated time left, etc.

   curl displays this data to the terminal by default, so  if  you  invoke
   curl  to do an operation and it is about to write data to the terminal,
   it disables the progress meter as otherwise it would mess up the output
   mixing progress meter and response data.

   If you want a progress meter for HTTP POST or PUT requests, you need to
   redirect the response output to a file, using shell  redirect  (>),  -o
   [file] or similar.

   It  is not the same case for FTP upload as that operation does not spit
   out any response data to the terminal.

   If you prefer a progress "bar" instead of the regular meter, -# is your
   friend.

OPTIONS Options start with one or two dashes. Many of the options require an additional value next to them.

   The short "single-dash" form of the options, -d  for  example,  may  be
   used with or without a space between it and its value, although a space
   is a recommended separator. The long  "double-dash"  form,  --data  for
   example, requires a space between it and its value.

   Short version options that don't need any additional values can be used
   immediately next to each other, like for example you  can  specify  all
   the options -O, -L and -v at once as -OLv.

   In general, all boolean options are enabled with --option and yet again
   disabled with --no-option. That is, you use the exact same option  name
   but prefix it with "no-". However, in this list we mostly only list and
   show the --option version of them. (This concept with --no options  was
   added  in  7.19.0.  Previously  most  options  were  toggled  on/off on
   repeated use of the same command line option.)

   -#, --progress-bar
          Make curl display progress as a simple progress bar  instead  of
          the standard, more informational, meter.

   -:, --next
          Tells curl to use a separate operation for the following URL and
          associated  options.  This  allows  you  to  send  several   URL
          requests,  each  with  their  own specific options, for example,
          such as different user names or custom requests for each. (Added
          in 7.36.0)

   -0, --http1.0
          (HTTP)  Tells  curl to use HTTP version 1.0 instead of using its
          internally preferred: HTTP 1.1.

   --http1.1
          (HTTP) Tells curl to use HTTP version 1.1. This is the  internal
          default version. (Added in 7.33.0)

   --http2
          (HTTP)  Tells  curl  to  issue  its  requests using HTTP 2. This
          requires that the underlying libcurl was built  to  support  it.
          (Added in 7.33.0)

   --no-npn
          Disable  the  NPN  TLS  extension.  NPN is enabled by default if
          libcurl was built with an SSL library that supports NPN. NPN  is
          used  by a libcurl that supports HTTP 2 to negotiate HTTP 2 sup‐
          port with the server during https sessions.

          (Added in 7.36.0)

   --no-alpn
          Disable the ALPN TLS extension. ALPN is enabled  by  default  if
          libcurl  was  built with an SSL library that supports ALPN. ALPN
          is used by a libcurl that supports HTTP 2 to  negotiate  HTTP  2
          support with the server during https sessions.

          (Added in 7.36.0)

   -1, --tlsv1
          (SSL) Forces curl to use TLS version 1.x when negotiating with a
          remote TLS server.  You can use  options  --tlsv1.0,  --tlsv1.1,
          and  --tlsv1.2 to control the TLS version more precisely (if the
          SSL backend in use supports such a level of control).

   -2, --sslv2
          (SSL) Forces curl to use SSL version 2 when negotiating  with  a
          remote  SSL  server.  Sometimes curl is built without SSLv2 sup‐
          port. SSLv2 is widely considered insecure (see RFC 6176).

   -3, --sslv3
          (SSL) Forces curl to use SSL version 3 when negotiating  with  a
          remote  SSL  server.  Sometimes curl is built without SSLv3 sup‐
          port. SSLv3 is widely considered insecure (see RFC 7568).

   -4, --ipv4
          This option tells curl to resolve names to IPv4 addresses  only,
          and not for example try IPv6.

   -6, --ipv6
          This  option tells curl to resolve names to IPv6 addresses only,
          and not for example try IPv4.

   -a, --append
          (FTP/SFTP) When used in an upload, this makes curl append to the
          target  file  instead  of  overwriting  it.  If  the remote file
          doesn't exist, it will be  created.   Note  that  this  flag  is
          ignored by some SFTP servers (including OpenSSH).

   -A, --user-agent <agent string>
          (HTTP) Specify the User-Agent string to send to the HTTP server.
          Some  badly  done  CGIs  fail  if  this  field  isn't   set   to
          "Mozilla/4.0".  To  encode  blanks  in  the string, surround the
          string with single quote marks. This can also be  set  with  the
          -H, --header option of course.

          If this option is used several times, the last one will be used.

   --anyauth
          (HTTP) Tells curl to figure out authentication method by itself,
          and use the most secure one the remote site claims  to  support.
          This is done by first doing a request and checking the response-
          headers, thus possibly inducing  an  extra  network  round-trip.
          This  is  used  instead  of  setting  a  specific authentication
          method, which you can do with  --basic,  --digest,  --ntlm,  and
          --negotiate.

          Note  that  using --anyauth is not recommended if you do uploads
          from stdin, since it may require data to be sent twice and  then
          the client must be able to rewind. If the need should arise when
          uploading from stdin, the upload operation will fail.

   -b, --cookie <name=data>
          (HTTP) Pass the data to the HTTP server as a cookie. It is  sup‐
          posedly  the data previously received from the server in a "Set-
          Cookie:" line.  The data should be in the format  "NAME1=VALUE1;
          NAME2=VALUE2".

          If  no  '=' symbol is used in the line, it is treated as a file‐
          name to use to read previously stored cookie lines  from,  which
          should  be used in this session if they match. Using this method
          also activates the cookie engine which  will  make  curl  record
          incoming cookies too, which may be handy if you're using this in
          combination with the -L, --location option. The file  format  of
          the  file  to  read cookies from should be plain HTTP headers or
          the Netscape/Mozilla cookie file format.

          The file specified with -b, --cookie is only used as  input.  No
          cookies  will  be written to the file. To store cookies, use the
          -c, --cookie-jar option.

          Exercise caution if you  are  using  this  option  and  multiple
          transfers may occur.  If you use the NAME1=VALUE1; format, or in
          a file use the Set-Cookie format and  don't  specify  a  domain,
          then the cookie is sent for any domain (even after redirects are
          followed) and cannot be modified by a server-set cookie. If  the
          cookie  engine is enabled and a server sets a cookie of the same
          name then both will be sent on a future transfer to that server,
          likely  not  what  you  intended.  To address these issues set a
          domain in Set-Cookie (doing that will  include  sub-domains)  or
          use the Netscape format.

          If this option is used several times, the last one will be used.

   -B, --use-ascii
          (FTP/LDAP)  Enable  ASCII  transfer.  For  FTP, this can also be
          enforced by using an URL that ends with ";type=A".  This  option
          causes data sent to stdout to be in text mode for win32 systems.

   --basic
          (HTTP)  Tells  curl  to  use  HTTP Basic authentication with the
          remote host. This is the default  and  this  option  is  usually
          pointless, unless you use it to override a previously set option
          that sets a different authentication  method  (such  as  --ntlm,
          --digest, or --negotiate).

          Used together with -u, --user and -x, --proxy.

          See also --proxy-basic.

   -c, --cookie-jar <file name>
          (HTTP)  Specify to which file you want curl to write all cookies
          after a completed operation. Curl writes all cookies  previously
          read  from a specified file as well as all cookies received from
          remote server(s). If no cookies are known, no data will be writ‐
          ten.  The  file  will  be written using the Netscape cookie file
          format. If you set the file name to  a  single  dash,  "-",  the
          cookies will be written to stdout.

          This  command  line  option will activate the cookie engine that
          makes curl record and use cookies. Another way to activate it is
          to use the -b, --cookie option.

          If the cookie jar can't be created or written to, the whole curl
          operation won't fail or even report an error clearly.  Using  -v
          will get a warning displayed, but that is the only visible feed‐
          back you get about this possibly lethal situation.

          Since 7.43.0 cookies that were imported in the Set-Cookie format
          without a domain name are not exported by this option.

          If  this  option  is used several times, the last specified file
          name will be used.

   -C, --continue-at <offset>
          Continue/Resume a previous file transfer at  the  given  offset.
          The  given  offset  is  the  exact  number of bytes that will be
          skipped, counting from the beginning of the source  file  before
          it is transferred to the destination.  If used with uploads, the
          FTP server command SIZE will not be used by curl.

          Use "-C -" to tell curl to automatically find out  where/how  to
          resume  the  transfer. It then uses the given output/input files
          to figure that out.

          If this option is used several times, the last one will be used.

   --ciphers <list of ciphers>
          (SSL) Specifies which ciphers to use in the connection. The list
          of  ciphers  must  specify  valid ciphers. Read up on SSL cipher
          list          details           on           this           URL:
          https://www.openssl.org/docs/apps/ciphers.html

          NSS  ciphers  are  done differently than OpenSSL and GnuTLS. The
          full list of NSS ciphers is in the NSSCipherSuite entry at  this
          URL:                                         https://git.fedora‐
          hosted.org/cgit/mod_nss.git/plain/docs/mod_nss.html#Directives

          If this option is used several times, the last one will be used.

   --compressed
          (HTTP) Request a compressed response using one of the algorithms
          curl  supports,  and  save  the  uncompressed document.  If this
          option is used and the server  sends  an  unsupported  encoding,
          curl will report an error.

   --connect-timeout <seconds>
          Maximum  time  in  seconds  that  you allow curl's connection to
          take.  This only limits the connection phase, so  if  curl  con‐
          nects  within the given period it will continue - if not it will
          exit.  Since version 7.32.0, this option accepts decimal values.

          See also the -m, --max-time option.

          If this option is used several times, the last one will be used.

   --create-dirs
          When used in conjunction with the -o option,  curl  will  create
          the  necessary  local directory hierarchy as needed. This option
          creates the dirs mentioned with the -o option, nothing else.  If
          the  -o file name uses no dir or if the dirs it mentions already
          exist, no dir will be created.

          To create remote directories when using FTP or SFTP, try  --ftp-
          create-dirs.

   --crlf Convert LF to CRLF in upload. Useful for MVS (OS/390).

          (SMTP added in 7.40.0)

   --crlfile <file>
          (HTTPS/FTPS)  Provide a file using PEM format with a Certificate
          Revocation List that may specify peer certificates that  are  to
          be considered revoked.

          If this option is used several times, the last one will be used.

          (Added in 7.19.7)

   -d, --data <data>
          (HTTP)  Sends  the  specified data in a POST request to the HTTP
          server, in the same way that a browser  does  when  a  user  has
          filled  in an HTML form and presses the submit button. This will
          cause curl to pass the data to the server using the content-type
          application/x-www-form-urlencoded.  Compare to -F, --form.

          -d, --data is the same as --data-ascii. --data-raw is almost the
          same but does not have a special interpretation of the @ charac‐
          ter.  To  post  data  purely  binary, you should instead use the
          --data-binary option.  To URL-encode the value of a  form  field
          you may use --data-urlencode.

          If  any of these options is used more than once on the same com‐
          mand line, the data pieces specified  will  be  merged  together
          with  a  separating  &-symbol.  Thus,  using  '-d name=daniel -d
          skill=lousy'  would  generate  a  post  chunk  that  looks  like
          'name=daniel&skill=lousy'.

          If  you  start  the data with the letter @, the rest should be a
          file name to read the data from, or - if you want curl  to  read
          the data from stdin. Multiple files can also be specified. Post‐
          ing data from a file named 'foobar'  would  thus  be  done  with
          --data  @foobar.  When  --data  is told to read from a file like
          that, carriage returns and newlines will be stripped out. If you
          don't  want the @ character to have a special interpretation use
          --data-raw instead.

   -D, --dump-header <file>
          Write the protocol headers to the specified file.

          This option is handy to use when you want to store  the  headers
          that  an  HTTP site sends to you. Cookies from the headers could
          then be read in a  second  curl  invocation  by  using  the  -b,
          --cookie  option! The -c, --cookie-jar option is a better way to
          store cookies.

          When used in FTP, the FTP server response lines  are  considered
          being "headers" and thus are saved there.

          If this option is used several times, the last one will be used.

   --data-ascii <data>
          See -d, --data.

   --data-binary <data>
          (HTTP)  This  posts data exactly as specified with no extra pro‐
          cessing whatsoever.

          If you start the data with the letter @, the rest  should  be  a
          filename.   Data  is  posted in a similar manner as --data-ascii
          does, except that newlines and carriage  returns  are  preserved
          and conversions are never done.

          If  this  option  is  used several times, the ones following the
          first will append data as described in -d, --data.

   --data-raw <data>
          (HTTP) This posts data similarly to --data but without the  spe‐
          cial  interpretation of the @ character. See -d, --data.  (Added
          in 7.43.0)

   --data-urlencode <data>
          (HTTP) This posts data, similar to the other --data options with
          the exception that this performs URL-encoding. (Added in 7.18.0)

          To  be  CGI-compliant,  the <data> part should begin with a name
          followed by a separator and a content specification. The  <data>
          part can be passed to curl using one of the following syntaxes:

          content
                 This  will make curl URL-encode the content and pass that
                 on. Just be careful so that the content  doesn't  contain
                 any  =  or  @  symbols, as that will then make the syntax
                 match one of the other cases below!

          =content
                 This will make curl URL-encode the content and pass  that
                 on. The preceding = symbol is not included in the data.

          name=content
                 This  will make curl URL-encode the content part and pass
                 that on. Note that the name part is expected to  be  URL-
                 encoded already.

          @filename
                 This  will  make  curl  load  data  from  the  given file
                 (including any newlines), URL-encode that data  and  pass
                 it on in the POST.

          name@filename
                 This  will  make  curl  load  data  from  the  given file
                 (including any newlines), URL-encode that data  and  pass
                 it  on  in  the  POST.  The  name part gets an equal sign
                 appended, resulting in name=urlencoded-file-content. Note
                 that the name is expected to be URL-encoded already.

   --delegation LEVEL
          Set LEVEL to tell the server what it is allowed to delegate when
          it comes to user credentials. Used with GSS/kerberos.

          none   Don't allow any delegation.

          policy Delegates if and only if the OK-AS-DELEGATE flag  is  set
                 in  the  Kerberos  service  ticket,  which is a matter of
                 realm policy.

          always Unconditionally allow the server to delegate.

   --digest
          (HTTP) Enables HTTP Digest authentication. This is an  authenti‐
          cation  scheme  that  prevents the password from being sent over
          the wire in clear text. Use this in combination with the  normal
          -u,  --user  option  to  set  user  name  and password. See also
          --ntlm, --negotiate and --anyauth for related options.

          If this option is used several times,  only  the  first  one  is
          used.

   --disable-eprt
          (FTP) Tell curl to disable the use of the EPRT and LPRT commands
          when doing active FTP transfers. Curl will normally always first
          attempt  to use EPRT, then LPRT before using PORT, but with this
          option, it will use PORT right away. EPRT and  LPRT  are  exten‐
          sions  to  the  original  FTP  protocol, and may not work on all
          servers, but they enable more functionality in a better way than
          the traditional PORT command.

          --eprt can be used to explicitly enable EPRT again and --no-eprt
          is an alias for --disable-eprt.

          Disabling EPRT only changes the active behavior. If you want  to
          switch  to  passive  mode  you need to not use -P, --ftp-port or
          force it with --ftp-pasv.

   --disable-epsv
          (FTP) Tell curl to disable the use  of  the  EPSV  command  when
          doing  passive  FTP  transfers.  Curl will normally always first
          attempt to use EPSV before PASV, but with this option,  it  will
          not try using EPSV.

          --epsv can be used to explicitly enable EPSV again and --no-epsv
          is an alias for --disable-epsv.

          Disabling EPSV only changes the passive behavior. If you want to
          switch to active mode you need to use -P, --ftp-port.

   --dns-interface <interface>
          Tell  curl  to  send  outgoing DNS requests through <interface>.
          This option is a counterpart  to  --interface  (which  does  not
          affect  DNS). The supplied string must be an interface name (not
          an address).

          This option requires that libcurl  was  built  with  a  resolver
          backend  that supports this operation. The c-ares backend is the
          only such one. (Added in 7.33.0)

   --dns-ipv4-addr <ip-address>
          Tell curl to bind to <ip-address> when making IPv4 DNS requests,
          so  that the DNS requests originate from this address. The argu‐
          ment should be a single IPv4 address.

          This option requires that libcurl  was  built  with  a  resolver
          backend  that supports this operation. The c-ares backend is the
          only such one.  (Added in 7.33.0)

   --dns-ipv6-addr <ip-address>
          Tell curl to bind to <ip-address> when making IPv6 DNS requests,
          so  that the DNS requests originate from this address. The argu‐
          ment should be a single IPv6 address.

          This option requires that libcurl  was  built  with  a  resolver
          backend  that supports this operation. The c-ares backend is the
          only such one.  (Added in 7.33.0)

   --dns-servers <ip-address,ip-address>
          Set the list of DNS servers to be used  instead  of  the  system
          default.  The list of IP addresses should be separated with com‐
          mas. Port numbers may also optionally be given as :<port-number>
          after each IP address.

          This  option  requires  that  libcurl  was built with a resolver
          backend that supports this operation. The c-ares backend is  the
          only such one.  (Added in 7.33.0)

   -e, --referer <URL>
          (HTTP) Sends the "Referrer Page" information to the HTTP server.
          This can also be set with the -H, --header flag of course.  When
          used with -L, --location you can append ";auto" to the --referer
          URL to make curl automatically set the previous URL when it fol‐
          lows  a  Location: header. The ";auto" string can be used alone,
          even if you don't set an initial --referer.

          If this option is used several times, the last one will be used.

   -E, --cert <certificate[:password]>
          (SSL) Tells curl to use the specified  client  certificate  file
          when getting a file with HTTPS, FTPS or another SSL-based proto‐
          col. The certificate must be in PKCS#12 format if  using  Secure
          Transport,  or  PEM  format  if  using any other engine.  If the
          optional password isn't specified, it will be queried for on the
          terminal.  Note  that  this  option assumes a "certificate" file
          that is the private key and the client certificate concatenated!
          See --cert and --key to specify them independently.

          If  curl  is  built against the NSS SSL library then this option
          can tell curl the nickname of the certificate to use within  the
          NSS  database defined by the environment variable SSL_DIR (or by
          default /etc/pki/nssdb). If the NSS  PEM  PKCS#11  module  (lib‐
          nsspem.so)  is  available  then  PEM files may be loaded. If you
          want to use a file from the current directory, please precede it
          with  "./"  prefix, in order to avoid confusion with a nickname.
          If the nickname contains ":", it needs to be preceded by "\"  so
          that  it  is not recognized as password delimiter.  If the nick‐
          name contains "\", it needs to be escaped as "\\" so that it  is
          not recognized as an escape character.

          (iOS  and  Mac OS X only) If curl is built against Secure Trans‐
          port, then the certificate string can either be the  name  of  a
          certificate/private  key  in the system or user keychain, or the
          path to a PKCS#12-encoded certificate and private  key.  If  you
          want to use a file from the current directory, please precede it
          with "./" prefix, in order to avoid confusion with a nickname.

          If this option is used several times, the last one will be used.

   --engine <name>
          Select the OpenSSL crypto engine to use for  cipher  operations.
          Use  --engine  list  to  print  a  list  of build-time supported
          engines. Note that not all (or  none)  of  the  engines  may  be
          available at run-time.

   --environment
          (RISC  OS ONLY) Sets a range of environment variables, using the
          names the -w option supports, to allow easier extraction of use‐
          ful information after having run curl.

   --egd-file <file>
          (SSL)  Specify  the  path  name  to the Entropy Gathering Daemon
          socket. The socket is used to seed the  random  engine  for  SSL
          connections. See also the --random-file option.

   --expect100-timeout <seconds>
          (HTTP) Maximum time in seconds that you allow curl to wait for a
          100-continue response when curl emits an  Expects:  100-continue
          header  in  its  request.  By default curl will wait one second.
          This option accepts decimal values! When curl stops waiting,  it
          will continue as if the response has been received.

          (Added in 7.47.0)

   --cert-type <type>
          (SSL)  Tells curl what certificate type the provided certificate
          is in. PEM, DER and ENG are recognized types.  If not specified,
          PEM is assumed.

          If this option is used several times, the last one will be used.

   --cacert <CA certificate>
          (SSL) Tells curl to use the specified certificate file to verify
          the peer. The file may contain  multiple  CA  certificates.  The
          certificate(s)  must be in PEM format. Normally curl is built to
          use a default file for this, so this option is typically used to
          alter that default file.

          curl  recognizes the environment variable named 'CURL_CA_BUNDLE'
          if it is set, and uses the given path as a path  to  a  CA  cert
          bundle. This option overrides that variable.

          The  windows  version  of  curl will automatically look for a CA
          certs file named ´curl-ca-bundle.crt´, either in the same direc‐
          tory as curl.exe, or in the Current Working Directory, or in any
          folder along your PATH.

          If curl is built against  the  NSS  SSL  library,  the  NSS  PEM
          PKCS#11  module  (libnsspem.so)  needs  to be available for this
          option to work properly.

          If this option is used several times, the last one will be used.

   --capath <CA certificate directory>
          (SSL) Tells curl to use the specified certificate  directory  to
          verify  the  peer.  Multiple paths can be provided by separating
          them with ":" (e.g.  "path1:path2:path3"). The certificates must
          be  in  PEM  format,  and  if curl is built against OpenSSL, the
          directory must have been processed using  the  c_rehash  utility
          supplied  with OpenSSL. Using --capath can allow OpenSSL-powered
          curl to make SSL-connections much more  efficiently  than  using
          --cacert if the --cacert file contains many CA certificates.

          If this option is set, the default capath value will be ignored,
          and if it is used several times, the last one will be used.

   --pinnedpubkey <pinned public key (hashes)>
          (SSL) Tells curl to  use  the  specified  public  key  file  (or
          hashes)  to  verify the peer. This can be a path to a file which
          contains a single public key in PEM or DER format, or any number
          of base64 encoded sha256 hashes preceded by ´sha256//´ and sepa‐
          rated by ´;´

          When negotiating a TLS or SSL connection,  the  server  sends  a
          certificate  indicating  its identity. A public key is extracted
          from this certificate and if it does not exactly match the  pub‐
          lic  key provided to this option, curl will abort the connection
          before sending or receiving any data.

          Added in 7.39.0 for OpenSSL, GnuTLS and GSKit. Added  in  7.43.0
          for  NSS  and wolfSSL/CyaSSL. sha256 support added in 7.44.0 for
          OpenSSL, GnuTLS, NSS and wolfSSL/CyaSSL. Other SSL backends  not
          supported.

          If this option is used several times, the last one will be used.

   --cert-status
          (SSL)  Tells curl to verify the status of the server certificate
          by using the Certificate Status Request (aka. OCSP stapling) TLS
          extension.

          If  this option is enabled and the server sends an invalid (e.g.
          expired) response, if the response suggests that the server cer‐
          tificate  has  been  revoked, or no response at all is received,
          the verification fails.

          This is currently only implemented in the  OpenSSL,  GnuTLS  and
          NSS backends.  (Added in 7.41.0)

   --false-start

          (SSL)  Tells  curl  to use false start during the TLS handshake.
          False start is a mode where a  TLS  client  will  start  sending
          application data before verifying the server's Finished message,
          thus saving a round trip when performing a full handshake.

          This is currently only implemented in the NSS and Secure  Trans‐
          port  (on  iOS  7.0  or  later, or OS X 10.9 or later) backends.
          (Added in 7.42.0)

   -f, --fail
          (HTTP) Fail silently (no output at all) on server  errors.  This
          is  mostly done to better enable scripts etc to better deal with
          failed attempts. In normal cases when an HTTP  server  fails  to
          deliver  a  document,  it  returns  an  HTML document stating so
          (which often also describes why and more). This flag  will  pre‐
          vent curl from outputting that and return error 22.

          This  method is not fail-safe and there are occasions where non-
          successful response codes will  slip  through,  especially  when
          authentication is involved (response codes 401 and 407).

   -F, --form <name=content>
          (HTTP)  This  lets curl emulate a filled-in form in which a user
          has pressed the submit button. This causes  curl  to  POST  data
          using  the  Content-Type  multipart/form-data  according  to RFC
          2388. This enables uploading of binary files etc. To  force  the
          'content'  part  to  be  a  file, prefix the file name with an @
          sign. To just get the content part from a file, prefix the  file
          name  with  the symbol <. The difference between @ and < is then
          that @ makes a file get attached in the post as a  file  upload,
          while  the  <  makes  a text field and just get the contents for
          that text field from a file.

          Example, to send your password file to the server, where  'pass‐
          word' is the name of the form-field to which /etc/passwd will be
          the input:

          curl -F password=@/etc/passwd www.mypasswords.com

          To read content from stdin instead of a file, use - as the file‐
          name.  This  goes  for both @ and < constructs. Unfortunately it
          does not support reading the file from a named pipe or  similar,
          as it needs the full size before the transfer starts.

          You  can  also  tell  curl  what  Content-Type  to  use by using
          'type=', in a manner similar to:

          curl -F "[email protected];type=text/html" url.com

          or

          curl -F "name=daniel;type=text/foo" url.com

          You can also explicitly change the name field of a  file  upload
          part by setting filename=, like this:

          curl -F "file=@localfile;filename=nameinpost" url.com

          If  filename/path contains ',' or ';', it must be quoted by dou‐
          ble-quotes like:

          curl -F "file=@\"localfile\";filename=\"nameinpost\"" url.com

          or

          curl -F 'file=@"localfile";filename="nameinpost"' url.com

          Note that if a filename/path is  quoted  by  double-quotes,  any
          double-quote or backslash within the filename must be escaped by
          backslash.

          See further examples and details in the MANUAL.

          This option can be used multiple times.

   --ftp-account [data]
          (FTP) When an FTP server asks for "account data" after user name
          and  password has been provided, this data is sent off using the
          ACCT command. (Added in 7.13.0)

          If this option is used several times, the last one will be used.

   --ftp-alternative-to-user <command>
          (FTP) If authenticating with the USER and PASS  commands  fails,
          send  this  command.   When  connecting  to  Tumbleweed's Secure
          Transport server over FTPS using  a  client  certificate,  using
          "SITE  AUTH"  will tell the server to retrieve the username from
          the certificate. (Added in 7.15.5)

   --ftp-create-dirs
          (FTP/SFTP) When an FTP or SFTP URL/operation uses  a  path  that
          doesn't  currently exist on the server, the standard behavior of
          curl is to fail. Using this option, curl will instead attempt to
          create missing directories.

   --ftp-method [method]
          (FTP)  Control what method curl should use to reach a file on an
          FTP(S) server. The method argument should be one of the  follow‐
          ing alternatives:

          multicwd
                 curl  does  a  single CWD operation for each path part in
                 the given URL. For deep hierarchies this means very  many
                 commands.  This  is  how RFC 1738 says it should be done.
                 This is the default but the slowest behavior.

          nocwd  curl does no CWD at all. curl will do  SIZE,  RETR,  STOR
                 etc and give a full path to the server for all these com‐
                 mands. This is the fastest behavior.

          singlecwd
                 curl does one CWD with the full target directory and then
                 operates  on  the  file  "normally" (like in the multicwd
                 case). This is somewhat  more  standards  compliant  than
                 'nocwd' but without the full penalty of 'multicwd'.

          (Added in 7.15.1)

   --ftp-pasv
          (FTP)  Use  passive mode for the data connection. Passive is the
          internal default behavior, but using this option can be used  to
          override a previous -P/-ftp-port option. (Added in 7.11.0)

          If  this  option  is  used  several times, only the first one is
          used. Undoing an enforced passive really isn't  doable  but  you
          must then instead enforce the correct -P, --ftp-port again.

          Passive mode means that curl will try the EPSV command first and
          then PASV, unless --disable-epsv is used.

   --ftp-skip-pasv-ip
          (FTP) Tell curl to not use the IP address the server suggests in
          its  response to curl's PASV command when curl connects the data
          connection. Instead curl will re-use  the  same  IP  address  it
          already uses for the control connection. (Added in 7.14.2)

          This  option has no effect if PORT, EPRT or EPSV is used instead
          of PASV.

   --ftp-pret
          (FTP) Tell curl to send a PRET command before PASV  (and  EPSV).
          Certain  FTP  servers,  mainly drftpd, require this non-standard
          command for directory listings as well as up  and  downloads  in
          PASV mode.  (Added in 7.20.x)

   --ftp-ssl-ccc
          (FTP)  Use  CCC  (Clear  Command Channel) Shuts down the SSL/TLS
          layer after authenticating. The rest of the control channel com‐
          munication  will be unencrypted. This allows NAT routers to fol‐
          low the FTP transaction. The default mode is passive. See --ftp-
          ssl-ccc-mode for other modes.  (Added in 7.16.1)

   --ftp-ssl-ccc-mode [active/passive]
          (FTP)  Use  CCC  (Clear  Command Channel) Sets the CCC mode. The
          passive mode will not initiate the shutdown,  but  instead  wait
          for the server to do it, and will not reply to the shutdown from
          the server. The active mode initiates the shutdown and waits for
          a reply from the server.  (Added in 7.16.2)

   --ftp-ssl-control
          (FTP)  Require  SSL/TLS  for  the FTP login, clear for transfer.
          Allows secure authentication, but non-encrypted  data  transfers
          for  efficiency.   Fails the transfer if the server doesn't sup‐
          port SSL/TLS.  (Added in 7.16.0) that can still be used but will
          be removed in a future version.

   --form-string <name=string>
          (HTTP)  Similar  to  --form except that the value string for the
          named parameter is used literally. Leading '@' and  '<'  charac‐
          ters, and the ';type=' string in the value have no special mean‐
          ing. Use this in preference to --form if there's any possibility
          that  the  string  value may accidentally trigger the '@' or '<'
          features of --form.

   -g, --globoff
          This option switches off the "URL globbing parser". When you set
          this  option, you can specify URLs that contain the letters {}[]
          without having them being interpreted by curl itself. Note  that
          these  letters are not normal legal URL contents but they should
          be encoded according to the URI standard.

   -G, --get
          When used, this option will make all  data  specified  with  -d,
          --data,  --data-binary or --data-urlencode to be used in an HTTP
          GET request instead of the POST request that otherwise would  be
          used. The data will be appended to the URL with a '?' separator.

          If  used  in  combination with -I, the POST data will instead be
          appended to the URL with a HEAD request.

          If this option is used several times,  only  the  first  one  is
          used.  This is because undoing a GET doesn't make sense, but you
          should then instead enforce the alternative method you prefer.

   -H, --header <header>
          (HTTP) Extra header to include in the request when sending  HTTP
          to  a  server. You may specify any number of extra headers. Note
          that if you should add a custom header that has the same name as
          one  of  the  internal  ones curl would use, your externally set
          header will be used instead of the internal one. This allows you
          to  make  even  trickier  stuff than curl would normally do. You
          should not replace internally set headers without  knowing  per‐
          fectly well what you're doing. Remove an internal header by giv‐
          ing a replacement without content  on  the  right  side  of  the
          colon, as in: -H "Host:". If you send the custom header with no-
          value then its header must be terminated with a semicolon,  such
          as -H "X-Custom-Header;" to send "X-Custom-Header:".

          curl  will  make  sure  that each header you add/replace is sent
          with the proper end-of-line marker, you should thus not add that
          as a part of the header content: do not add newlines or carriage
          returns, they will only mess things up for you.

          See also the -A, --user-agent and -e, --referer options.

          Starting in 7.37.0, you need --proxy-header to send custom head‐
          ers intended for a proxy.

          Example:

          # curl -H "X-First-Name: Joe" http://192.168.0.1/

          WARNING:  headers  set  with  this  option  will  be  set in all
          requests - even after redirects are  followed,  like  when  told
          with  -L,  --location. This can lead to the header being sent to
          other hosts than the original host, so sensitive headers  should
          be used with caution combined with following redirects.

          This  option  can  be  used multiple times to add/replace/remove
          multiple headers.

   --hostpubmd5 <md5>
          (SCP/SFTP) Pass a string containing 32 hexadecimal  digits.  The
          string  should  be the 128 bit MD5 checksum of the remote host's
          public key, curl will refuse the connection with the host unless
          the md5sums match. (Added in 7.17.1)

   --ignore-content-length
          For HTTP, Ignore the Content-Length header. This is particularly
          useful for servers running Apache 1.x, which will report  incor‐
          rect Content-Length for files larger than 2 gigabytes.

          For  FTP (since 7.46.0), skip the RETR command to figure out the
          size before downloading a file.

   -i, --include
          (HTTP) Include the HTTP-header in the  output.  The  HTTP-header
          includes  things  like  server-name, date of the document, HTTP-
          version and more...

   -I, --head
          (HTTP/FTP/FILE) Fetch the HTTP-header only! HTTP-servers feature
          the  command  HEAD which this uses to get nothing but the header
          of a document. When used on an FTP or FILE file,  curl  displays
          the file size and last modification time only.

   --interface <name>
          Perform  an operation using a specified interface. You can enter
          interface name, IP address or host name. An example  could  look
          like:

           curl --interface eth0:1 http://www.netscape.com/

          If this option is used several times, the last one will be used.

   -j, --junk-session-cookies
          (HTTP) When curl is told to read cookies from a given file, this
          option will make it discard all  "session  cookies".  This  will
          basically  have  the same effect as if a new session is started.
          Typical browsers always discard  session  cookies  when  they're
          closed down.

   -J, --remote-header-name
          (HTTP) This option tells the -O, --remote-name option to use the
          server-specified   Content-Disposition   filename   instead   of
          extracting a filename from the URL.

          There's  no  attempt to decode %-sequences (yet) in the provided
          file name, so this option may provide you with rather unexpected
          file names.

   -k, --insecure
          (SSL)  This  option explicitly allows curl to perform "insecure"
          SSL connections and transfers. All SSL connections are attempted
          to  be  made secure by using the CA certificate bundle installed
          by default. This makes  all  connections  considered  "insecure"
          fail unless -k, --insecure is used.

          See     this    online    resource    for    further    details:
          http://curl.haxx.se/docs/sslcerts.html

   -K, --config <config file>
          Specify which config file to read curl arguments from. The  con‐
          fig  file  is a text file in which command line arguments can be
          written which then will be used as if they were written  on  the
          actual command line.

          Options  and their parameters must be specified on the same con‐
          fig file line, separated by whitespace,  colon,  or  the  equals
          sign.  Long  option  names can optionally be given in the config
          file without the initial double dashes and if so, the  colon  or
          equals  characters  can  be used as separators. If the option is
          specified with one or two dashes,  there  can  be  no  colon  or
          equals character between the option and its parameter.

          If the parameter is to contain whitespace, the parameter must be
          enclosed within quotes.  Within  double  quotes,  the  following
          escape  sequences  are  available:  \\, \", \t, \n, \r and \v. A
          backslash preceding any other letter is ignored.  If  the  first
          column of a config line is a '#' character, the rest of the line
          will be treated as a comment. Only write one option per physical
          line in the config file.

          Specify  the  filename  to -K, --config as '-' to make curl read
          the file from stdin.

          Note that to be able to specify a URL in the  config  file,  you
          need  to  specify  it  using the --url option, and not by simply
          writing the URL on its own line. So, it could  look  similar  to
          this:

          url = "http://curl.haxx.se/docs/"

          When curl is invoked, it always (unless -q is used) checks for a
          default config file and uses it if  found.  The  default  config
          file is checked for in the following places in this order:

          1)  curl  tries  to find the "home dir": It first checks for the
          CURL_HOME and then the HOME environment variables. Failing that,
          it  uses getpwuid() on Unix-like systems (which returns the home
          dir given the current user in your system). On Windows, it  then
          checks for the APPDATA variable, or as a last resort the '%USER‐
          PROFILE%\Application Data'.

          2) On windows, if there is no _curlrc file in the home  dir,  it
          checks for one in the same dir the curl executable is placed. On
          Unix-like systems, it will simply try to load .curlrc  from  the
          determined home dir.

          # --- Example file ---
          # this is a comment
          url = "curl.haxx.se"
          output = "curlhere.html"
          user-agent = "superagent/1.0"

          # and fetch another URL too
          url = "curl.haxx.se/docs/manpage.html"
          -O
          referer = "http://nowhereatall.com/"
          # --- End of example file ---

          This  option  can be used multiple times to load multiple config
          files.

   --keepalive-time <seconds>
          This option sets the time a  connection  needs  to  remain  idle
          before  sending keepalive probes and the time between individual
          keepalive probes. It is currently effective on operating systems
          offering  the  TCP_KEEPIDLE  and  TCP_KEEPINTVL  socket  options
          (meaning Linux, recent AIX, HP-UX and more). This option has  no
          effect if --no-keepalive is used. (Added in 7.18.0)

          If this option is used several times, the last one will be used.
          If unspecified, the option defaults to 60 seconds.

   --key <key>
          (SSL/SSH) Private key file name. Allows you to provide your pri‐
          vate  key in this separate file. For SSH, if not specified, curl
          tries  the  following  candidates  in  order:   '~/.ssh/id_rsa',
          '~/.ssh/id_dsa', './id_rsa', './id_dsa'.

          If this option is used several times, the last one will be used.

   --key-type <type>
          (SSL)  Private key file type. Specify which type your --key pro‐
          vided private key is. DER, PEM, and ENG are  supported.  If  not
          specified, PEM is assumed.

          If this option is used several times, the last one will be used.

   --krb <level>
          (FTP)  Enable Kerberos authentication and use. The level must be
          entered and should be one of 'clear', 'safe', 'confidential', or
          'private'.  Should  you  use  a  level that is not one of these,
          'private' will instead be used.

          This option requires a library  built  with  kerberos4  support.
          This  is  not very common. Use -V, --version to see if your curl
          supports it.

          If this option is used several times, the last one will be used.

   -l, --list-only
          (FTP) When listing an FTP directory, this switch forces a  name-
          only  view.  This  is  especially  useful  if  the user wants to
          machine-parse the contents of an FTP directory since the  normal
          directory  view doesn't use a standard look or format. When used
          like this, the option causes a NLST command to be  sent  to  the
          server instead of LIST.

          Note:  Some  FTP  servers  list  only files in their response to
          NLST; they do not include sub-directories and symbolic links.

          (POP3) When retrieving a specific email from POP3,  this  switch
          forces  a  LIST command to be performed instead of RETR. This is
          particularly useful if the user wants to see if a specific  mes‐
          sage id exists on the server and what size it is.

          Note:  When  combined  with -X, --request <command>, this option
          can be used to send an UIDL command instead, so the user may use
          the  email's  unique  identifier  rather than it's message id to
          make the request. (Added in 7.21.5)

   -L, --location
          (HTTP/HTTPS) If the server reports that the requested  page  has
          moved to a different location (indicated with a Location: header
          and a 3XX response code), this option will make  curl  redo  the
          request on the new place. If used together with -i, --include or
          -I, --head, headers from all requested pages will be shown. When
          authentication  is  used, curl only sends its credentials to the
          initial host. If a redirect takes curl to a different  host,  it
          won't  be  able to intercept the user+password. See also --loca‐
          tion-trusted on how to change this. You can limit the amount  of
          redirects to follow by using the --max-redirs option.

          When  curl follows a redirect and the request is not a plain GET
          (for example POST or PUT), it will do the following request with
          a GET if the HTTP response was 301, 302, or 303. If the response
          code was any other 3xx code, curl  will  re-send  the  following
          request using the same unmodified method.

          You  can  tell  curl to not change the non-GET request method to
          GET after a 30x response by  using  the  dedicated  options  for
          that: --post301, --post302 and -post303.

   --libcurl <file>
          Append  this  option  to any ordinary curl command line, and you
          will get a libcurl-using C source code written to the file  that
          does the equivalent of what your command-line operation does!

          If  this  option is used several times, the last given file name
          will be used. (Added in 7.16.1)

   --limit-rate <speed>
          Specify the maximum transfer rate you want curl  to  use  -  for
          both downloads and uploads. This feature is useful if you have a
          limited pipe and you'd like your transfer not to use your entire
          bandwidth. To make it slower than it otherwise would be.

          The  given speed is measured in bytes/second, unless a suffix is
          appended.  Appending 'k' or 'K' will count the number  as  kilo‐
          bytes,  'm'  or M' makes it megabytes, while 'g' or 'G' makes it
          gigabytes. Examples: 200K, 3m and 1G.

          The given rate is the average speed counted  during  the  entire
          transfer. It means that curl might use higher transfer speeds in
          short bursts, but over time it uses no more than the given rate.

          If you also use the -Y, --speed-limit option, that  option  will
          take precedence and might cripple the rate-limiting slightly, to
          help keeping the speed-limit logic working.

          If this option is used several times, the last one will be used.

   --local-port <num>[-num]
          Set a preferred number or range of local port numbers to use for
          the  connection(s).   Note  that  port  numbers  by nature are a
          scarce resource that will be busy at times so setting this range
          to something too narrow might cause unnecessary connection setup
          failures. (Added in 7.15.2)

   --location-trusted
          (HTTP/HTTPS) Like -L, --location, but  will  allow  sending  the
          name + password to all hosts that the site may redirect to. This
          may or may not introduce a security breach if the site redirects
          you  to  a  site  to  which you'll send your authentication info
          (which is plaintext in the case of HTTP Basic authentication).

   -m, --max-time <seconds>
          Maximum time in seconds that you allow the  whole  operation  to
          take.   This is useful for preventing your batch jobs from hang‐
          ing for hours due to slow networks or links going  down.   Since
          7.32.0, this option accepts decimal values, but the actual time‐
          out will decrease in accuracy as the specified timeout increases
          in decimal precision.  See also the --connect-timeout option.

          If this option is used several times, the last one will be used.

   --login-options <options>
          Specify the login options to use during server authentication.

          You  can  use  the  login  options  to specify protocol specific
          options that may be used during authentication. At present  only
          IMAP,  POP3 and SMTP support login options. For more information
          about the login options please see RFC 2384, RFC 5092  and  IETF
          draft draft-earhart-url-smtp-00.txt (Added in 7.34.0).

          If this option is used several times, the last one will be used.

   --mail-auth <address>
          (SMTP)  Specify  a  single address. This will be used to specify
          the authentication address (identity)  of  a  submitted  message
          that is being relayed to another server.

          (Added in 7.25.0)

   --mail-from <address>
          (SMTP)  Specify  a single address that the given mail should get
          sent from.

          (Added in 7.20.0)

   --max-filesize <bytes>
          Specify the maximum size (in bytes) of a file  to  download.  If
          the  file requested is larger than this value, the transfer will
          not start and curl will return with exit code 63.

          NOTE: The file size is not always known prior to  download,  and
          for such files this option has no effect even if the file trans‐
          fer ends up being larger than this given  limit.  This  concerns
          both FTP and HTTP transfers.

   --mail-rcpt <address>
          (SMTP) Specify a single address, user name or mailing list name.

          When  performing a mail transfer, the recipient should specify a
          valid email address to send the mail to. (Added in 7.20.0)

          When performing an  address  verification  (VRFY  command),  the
          recipient  should be specified as the user name or user name and
          domain (as per Section 3.5 of RFC5321). (Added in 7.34.0)

          When performing a mailing list expand (EXPN command), the recip‐
          ient  should  be  specified using the mailing list name, such as
          "Friends" or "London-Office".  (Added in 7.34.0)

   --max-redirs <num>
          Set maximum number of  redirection-followings  allowed.  If  -L,
          --location is used, this option can be used to prevent curl from
          following redirections "in absurdum". By default, the  limit  is
          set  to 50 redirections. Set this option to -1 to make it limit‐
          less.

          If this option is used several times, the last one will be used.

   --metalink
          This option can tell curl to parse and process a  given  URI  as
          Metalink  file  (both  version 3 and 4 (RFC 5854) are supported)
          and make use of the mirrors listed within for failover if  there
          are  errors (such as the file or server not being available). It
          will also verify the hash of the file after  the  download  com‐
          pletes.  The Metalink file itself is downloaded and processed in
          memory and not stored in the local file system.

          Example to use a remote Metalink file:

          curl --metalink http://www.example.com/example.metalink

          To use a Metalink file in the local file system, use FILE proto‐
          col (file://):

          curl --metalink file://example.metalink

          Please  note  that if FILE protocol is disabled, there is no way
          to use a local Metalink file at the time of this  writing.  Also
          note  that  if  --metalink  and  --include  are  used  together,
          --include will be ignored. This is because including headers  in
          the  response  will break Metalink parser and if the headers are
          included in the file described in Metalink file, hash check will
          fail.

          (Added in 7.27.0, if built against the libmetalink library.)

   -n, --netrc
          Makes  curl  scan  the  .netrc  (_netrc  on Windows) file in the
          user's home directory for login name and password. This is typi‐
          cally  used for FTP on Unix. If used with HTTP, curl will enable
          user authentication. See netrc(5) ftp(1) for details on the file
          format.  Curl  will  not  complain if that file doesn't have the
          right permissions (it should not be either world- or group-read‐
          able).  The environment variable "HOME" is used to find the home
          directory.

          A quick and very simple example of how  to  setup  a  .netrc  to
          allow  curl to FTP to the machine host.domain.com with user name
          'myself' and password 'secret' should look similar to:

          machine host.domain.com login myself password secret

   -N, --no-buffer
          Disables the buffering of the output stream. In normal work sit‐
          uations,  curl  will  use a standard buffered output stream that
          will have the effect that it will output the data in chunks, not
          necessarily  exactly  when  the data arrives.  Using this option
          will disable that buffering.

          Note that this is the negated option name  documented.  You  can
          thus use --buffer to enforce the buffering.

   --netrc-file
          This  option  is similar to --netrc, except that you provide the
          path (absolute or relative) to the netrc file that  Curl  should
          use.   You  can  only  specify one netrc file per invocation. If
          several --netrc-file options are provided,  only  the  last  one
          will be used.  (Added in 7.21.5)

          This  option  overrides  any use of --netrc as they are mutually
          exclusive.  It will also abide by --netrc-optional if specified.

   --netrc-optional
          Very similar to --netrc, but this option makes the .netrc  usage
          optional and not mandatory as the --netrc option does.

   --negotiate
          (HTTP) Enables Negotiate (SPNEGO) authentication.

          If  you  want to enable Negotiate (SPNEGO) for proxy authentica‐
          tion, then use --proxy-negotiate.

          This option requires a library built with GSS-API or  SSPI  sup‐
          port.  Use  -V,  --version  to  see  if  your curl supports GSS-
          API/SSPI and SPNEGO.

          When using this option, you must also provide a fake -u,  --user
          option  to  activate the authentication code properly. Sending a
          '-u :' is enough as the user  name  and  password  from  the  -u
          option aren't actually used.

          If  this  option  is  used  several times, only the first one is
          used.

   --no-keepalive
          Disables the use of keepalive messages on the TCP connection, as
          by default curl enables them.

          Note  that  this  is the negated option name documented. You can
          thus use --keepalive to enforce keepalive.

   --no-sessionid
          (SSL) Disable curl's use of SSL session-ID caching.  By  default
          all  transfers are done using the cache. Note that while nothing
          should ever get hurt by attempting  to  reuse  SSL  session-IDs,
          there seem to be broken SSL implementations in the wild that may
          require you to disable this in order for you to succeed.  (Added
          in 7.16.0)

          Note  that  this  is the negated option name documented. You can
          thus use --sessionid to enforce session-ID caching.

   --noproxy <no-proxy-list>
          Comma-separated list of hosts which do not use a proxy,  if  one
          is  specified.  The only wildcard is a single * character, which
          matches all hosts, and effectively disables the proxy. Each name
          in  this  list  is matched as either a domain which contains the
          hostname, or the hostname itself. For example,  local.com  would
          match   local.com,  local.com:80,  and  www.local.com,  but  not
          www.notlocal.com.  (Added in 7.19.4).

   --ntlm (HTTP) Enables  NTLM  authentication.  The  NTLM  authentication
          method was designed by Microsoft and is used by IIS web servers.
          It is a proprietary protocol, reverse-engineered by clever  peo‐
          ple and implemented in curl based on their efforts. This kind of
          behavior should not be endorsed, you should  encourage  everyone
          who  uses  NTLM to switch to a public and documented authentica‐
          tion method instead, such as Digest.

          If you want to enable NTLM for your proxy  authentication,  then
          use --proxy-ntlm.

          This  option  requires a library built with SSL support. Use -V,
          --version to see if your curl supports NTLM.

          If this option is used several times,  only  the  first  one  is
          used.

   -o, --output <file>
          Write output to <file> instead of stdout. If you are using {} or
          [] to fetch multiple documents, you can use '#'  followed  by  a
          number  in  the <file> specifier. That variable will be replaced
          with the current string for the URL being fetched. Like in:

            curl http://{one,two}.site.com -o "file_#1.txt"

          or use several variables like:

            curl http://{site,host}.host[1-5].com -o "#1_#2"

          You may use this option as many times as the number of URLs  you
          have.

          See  also  the --create-dirs option to create the local directo‐
          ries dynamically. Specifying the output as '-' (a  single  dash)
          will force the output to be done to stdout.

   -O, --remote-name
          Write  output to a local file named like the remote file we get.
          (Only the file part of the remote file is used, the path is  cut
          off.)

          The  remote  file  name  to use for saving is extracted from the
          given URL, nothing else.

          Consequentially, the file will be saved in the  current  working
          directory.  If you want the file saved in a different directory,
          make sure you change current working directory before you invoke
          curl with the -O, --remote-name flag!

          There is no URL decoding done on the file name. If it has %20 or
          other URL encoded parts of the name, they will end up  as-is  as
          file name.

          You  may use this option as many times as the number of URLs you
          have.

   --oauth2-bearer
          (IMAP, POP3, SMTP) Specify the Bearer Token for OAUTH 2.0 server
          authentication. The Bearer Token is used in conjunction with the
          user name which can be specified as part of  the  --url  or  -u,
          --user options.

          The  Bearer  Token  and user name are formatted according to RFC
          6750.

          If this option is used several times, the last one will be used.

   --proxy-header <header>
          (HTTP) Extra header to include in the request when sending  HTTP
          to a proxy. You may specify any number of extra headers. This is
          the equivalent option to -H, --header but is for proxy  communi‐
          cation  only  like  in CONNECT requests when you want a separate
          header sent to the proxy to what is sent to  the  actual  remote
          host.

          curl  will  make  sure  that each header you add/replace is sent
          with the proper end-of-line marker, you should thus not add that
          as a part of the header content: do not add newlines or carriage
          returns, they will only mess things up for you.

          Headers specified with this  option  will  not  be  included  in
          requests that curl knows will not be sent to a proxy.

          This  option  can  be  used multiple times to add/replace/remove
          multiple headers.

          (Added in 7.37.0)

   -p, --proxytunnel
          When an HTTP proxy is used (-x, --proxy), this option will cause
          non-HTTP  protocols  to  attempt  to  tunnel  through  the proxy
          instead of merely using it to do HTTP-like operations. The  tun‐
          nel  approach  is  made  with the HTTP proxy CONNECT request and
          requires that the proxy allows direct connect to the remote port
          number curl wants to tunnel through to.

   -P, --ftp-port <address>
          (FTP)  Reverses  the  default initiator/listener roles when con‐
          necting with FTP. This switch makes curl  use  active  mode.  In
          practice,  curl  then  tells  the  server to connect back to the
          client's specified address and port, while passive mode asks the
          server  to  setup  an  IP address and port for it to connect to.
          <address> should be one of:

          interface
                 i.e "eth0" to specify which interface's  IP  address  you
                 want to use (Unix only)

          IP address
                 i.e "192.168.10.1" to specify the exact IP address

          host name
                 i.e "my.host.domain" to specify the machine

          -      make  curl  pick the same IP address that is already used
                 for the control connection

          If this option is used several times, the last one will be used.
          Disable  the use of PORT with --ftp-pasv. Disable the attempt to
          use the EPRT command instead of PORT  by  using  --disable-eprt.
          EPRT is really PORT++.

          Starting in 7.19.5, you can append ":[start]-[end]" to the right
          of the address, to tell curl what TCP port range  to  use.  That
          means you specify a port range, from a lower to a higher number.
          A single number works as well, but do note that it increases the
          risk of failure since the port may not be available.

   --pass <phrase>
          (SSL/SSH) Passphrase for the private key

          If this option is used several times, the last one will be used.

   --path-as-is
          Tell  curl  to  not handle sequences of /../ or /./ in the given
          URL path. Normally curl will squash or merge them  according  to
          standards but with this option set you tell it not to do that.

          (Added in 7.42.0)

   --post301
          (HTTP) Tells curl to respect RFC 7230/6.4.2 and not convert POST
          requests into GET requests when following a 301 redirection. The
          non-RFC  behaviour  is  ubiquitous in web browsers, so curl does
          the conversion by default to maintain  consistency.  However,  a
          server  may  require  a POST to remain a POST after such a redi‐
          rection. This option is meaningful only when using  -L,  --loca‐
          tion (Added in 7.17.1)

   --post302
          (HTTP) Tells curl to respect RFC 7230/6.4.3 and not convert POST
          requests into GET requests when following a 302 redirection. The
          non-RFC  behaviour  is  ubiquitous in web browsers, so curl does
          the conversion by default to maintain  consistency.  However,  a
          server  may  require  a POST to remain a POST after such a redi‐
          rection. This option is meaningful only when using  -L,  --loca‐
          tion (Added in 7.19.1)

   --post303
          (HTTP) Tells curl to respect RFC 7230/6.4.4 and not convert POST
          requests into GET requests when following a 303 redirection. The
          non-RFC  behaviour  is  ubiquitous in web browsers, so curl does
          the conversion by default to maintain  consistency.  However,  a
          server  may  require  a POST to remain a POST after such a redi‐
          rection. This option is meaningful only when using  -L,  --loca‐
          tion (Added in 7.26.0)

   --proto <protocols>
          Tells   curl  to  use  the  listed  protocols  for  its  initial
          retrieval. Protocols are evaluated left to right, are comma sep‐
          arated,  and  are each a protocol name or 'all', optionally pre‐
          fixed by zero or more modifiers. Available modifiers are:

          +  Permit this protocol in addition to protocols already permit‐
             ted (this is the default if no modifier is used).

          -  Deny  this  protocol,  removing it from the list of protocols
             already permitted.

          =  Permit only this protocol (ignoring the list already  permit‐
             ted),  though  subject  to  later  modification by subsequent
             entries in the comma separated list.

          For example:

          --proto -ftps  uses the default protocols, but disables ftps

          --proto -all,https,+http
                         only enables http and https

          --proto =http,https
                         also only enables http and https

          Unknown protocols produce a  warning.  This  allows  scripts  to
          safely  rely on being able to disable potentially dangerous pro‐
          tocols, without relying upon support  for  that  protocol  being
          built into curl to avoid an error.

          This option can be used multiple times, in which case the effect
          is the same as concatenating the protocols into one instance  of
          the option.

          (Added in 7.20.2)

   --proto-default <protocol>
          Tells curl to use protocol for any URL missing a scheme name.

          Example:

          --proto-default https ftp.mozilla.org
                 https://ftp.mozilla.org

   An  unknown or unsupported protocol causes error CURLE_UNSUPPORTED_PRO‐
   TOCOL.

   This option does not change the default proxy protocol (http).

   Without this option curl would make a guess  based  on  the  host,  see
   --url for details.

   (Added in 7.45.0)

   --proto-redir <protocols>
          Tells  curl to use the listed protocols on redirect. See --proto
          for how protocols are represented.

          Example:

          --proto-redir -all,http,https
                 Allow only HTTP and HTTPS on redirect.

   By default curl will allow all protocols  on  redirect  except  several
   disabled  for security reasons: Since 7.19.4 FILE and SCP are disabled,
   and since 7.40.0 SMB and SMBS are also disabled. Specifying all or +all
   enables  all  protocols on redirect, including those disabled for secu‐
   rity.

   (Added in 7.20.2)

   --proxy-anyauth
          Tells curl to pick a suitable authentication method when  commu‐
          nicating  with  the  given  proxy.  This  might  cause  an extra
          request/response round-trip. (Added in 7.13.2)

   --proxy-basic
          Tells curl to use HTTP Basic authentication  when  communicating
          with the given proxy. Use --basic for enabling HTTP Basic with a
          remote host. Basic is the  default  authentication  method  curl
          uses with proxies.

   --proxy-digest
          Tells  curl to use HTTP Digest authentication when communicating
          with the given proxy. Use --digest for enabling HTTP Digest with
          a remote host.

   --proxy-negotiate
          Tells  curl  to  use HTTP Negotiate (SPNEGO) authentication when
          communicating with the given proxy. Use --negotiate for enabling
          HTTP Negotiate (SPNEGO) with a remote host. (Added in 7.17.1)

   --proxy-ntlm
          Tells  curl  to  use HTTP NTLM authentication when communicating
          with the given proxy. Use --ntlm for enabling NTLM with a remote
          host.

   --proxy-service-name <servicename>
          This  option  allows  you  to  change the service name for proxy
          negotiation.

          Examples:  --proxy-negotiate   proxy-name   --proxy-service-name
          sockd would use sockd/proxy-name.  (Added in 7.43.0).

   --proxy1.0 <proxyhost[:port]>
          Use  the  specified  HTTP  1.0  proxy. If the port number is not
          specified, it is assumed at port 1080.

          The only difference between this and the HTTP proxy option  (-x,
          --proxy), is that attempts to use CONNECT through the proxy will
          specify an HTTP 1.0 protocol instead of the default HTTP 1.1.

   --pubkey <key>
          (SSH) Public key file name. Allows you to  provide  your  public
          key in this separate file.

          If this option is used several times, the last one will be used.

          (As of 7.39.0, curl attempts to automatically extract the public
          key from the private key file, so passing this option is  gener‐
          ally not required. Note that this public key extraction requires
          libcurl to be linked against a copy of libssh2 1.2.8  or  higher
          that is itself linked against OpenSSL.)

   -q     If  used  as the first parameter on the command line, the curlrc
          config file will not be read and used. See the -K, --config  for
          details on the default config file search path.

   -Q, --quote <command>
          (FTP/SFTP)  Send  an arbitrary command to the remote FTP or SFTP
          server. Quote commands are sent BEFORE the transfer takes  place
          (just  after  the  initial PWD command in an FTP transfer, to be
          exact). To make commands take place after a successful transfer,
          prefix  them  with  a  dash '-'.  To make commands be sent after
          curl has changed the working directory, just before the transfer
          command(s),  prefix  the  command  with a '+' (this is only sup‐
          ported for FTP). You may specify any number of commands. If  the
          server returns failure for one of the commands, the entire oper‐
          ation will be aborted. You must send syntactically  correct  FTP
          commands  as  RFC 959 defines to FTP servers, or one of the com‐
          mands listed below to SFTP servers.  This  option  can  be  used
          multiple  times. When speaking to an FTP server, prefix the com‐
          mand with an asterisk (*) to make curl continue even if the com‐
          mand fails as by default curl will stop at first failure.

          SFTP  is a binary protocol. Unlike for FTP, curl interprets SFTP
          quote commands itself before sending them to the  server.   File
          names may be quoted shell-style to embed spaces or special char‐
          acters.  Following is the list of all supported SFTP quote  com‐
          mands:

          chgrp group file
                 The  chgrp command sets the group ID of the file named by
                 the file operand to the group ID specified by  the  group
                 operand. The group operand is a decimal integer group ID.

          chmod mode file
                 The  chmod  command  modifies  the  file mode bits of the
                 specified file. The mode operand is an octal integer mode
                 number.

          chown user file
                 The chown command sets the owner of the file named by the
                 file operand to the user ID specified by the  user  oper‐
                 and. The user operand is a decimal integer user ID.

          ln source_file target_file
                 The ln and symlink commands create a symbolic link at the
                 target_file location pointing to  the  source_file  loca‐
                 tion.

          mkdir directory_name
                 The  mkdir  command  creates  the  directory named by the
                 directory_name operand.

          pwd    The pwd command returns the absolute pathname of the cur‐
                 rent working directory.

          rename source target
                 The rename command renames the file or directory named by
                 the source operand to the destination path named  by  the
                 target operand.

          rm file
                 The rm command removes the file specified by the file op‐
                 erand.

          rmdir directory
                 The rmdir command removes the directory  entry  specified
                 by the directory operand, provided it is empty.

          symlink source_file target_file
                 See ln.

   -r, --range <range>
          (HTTP/FTP/SFTP/FILE)  Retrieve a byte range (i.e a partial docu‐
          ment) from a HTTP/1.1, FTP or  SFTP  server  or  a  local  FILE.
          Ranges can be specified in a number of ways.

          0-499     specifies the first 500 bytes

          500-999   specifies the second 500 bytes

          -500      specifies the last 500 bytes

          9500-     specifies the bytes from offset 9500 and forward

          0-0,-1    specifies the first and last byte only(*)(HTTP)

          100-199,500-599
                    specifies two separate 100-byte ranges(*) (HTTP)

          (*)  = NOTE that this will cause the server to reply with a mul‐
          tipart response!

          Only digit characters (0-9) are valid in the 'start' and  'stop'
          fields  of the 'start-stop' range syntax. If a non-digit charac‐
          ter is given in the range, the server's response will be unspec‐
          ified, depending on the server's configuration.

          You  should also be aware that many HTTP/1.1 servers do not have
          this feature enabled, so that when you attempt to get  a  range,
          you'll instead get the whole document.

          FTP  and  SFTP  range  downloads only support the simple 'start-
          stop' syntax (optionally with one of the numbers  omitted).  FTP
          use depends on the extended FTP command SIZE.

          If this option is used several times, the last one will be used.

   -R, --remote-time
          When  used,  this will make curl attempt to figure out the time‐
          stamp of the remote file, and if  that  is  available  make  the
          local file get that same timestamp.

   --random-file <file>
          (SSL) Specify the path name to file containing what will be con‐
          sidered as random data. The data is  used  to  seed  the  random
          engine for SSL connections.  See also the --egd-file option.

   --raw  (HTTP) When used, it disables all internal HTTP decoding of con‐
          tent or transfer encodings and  instead  makes  them  passed  on
          unaltered, raw. (Added in 7.16.2)

   --remote-name-all
          This  option changes the default action for all given URLs to be
          dealt with as if -O, --remote-name were used for each one. So if
          you want to disable that for a specific URL after --remote-name-
          all has been used, you must  use  "-o  -"  or  --no-remote-name.
          (Added in 7.19.0)

   --resolve <host:port:address>
          Provide  a  custom  address  for  a specific host and port pair.
          Using this, you can make the curl requests(s)  use  a  specified
          address  and  prevent the otherwise normally resolved address to
          be used. Consider it a sort of /etc/hosts  alternative  provided
          on  the  command line. The port number should be the number used
          for the specific protocol the host will be used  for.  It  means
          you  need several entries if you want to provide address for the
          same host but different ports.

          This option can be used many times to add  many  host  names  to
          resolve.

          (Added in 7.21.3)

   --retry <num>
          If  a  transient  error is returned when curl tries to perform a
          transfer, it will retry this number of times before  giving  up.
          Setting  the  number to 0 makes curl do no retries (which is the
          default). Transient error means either: a timeout,  an  FTP  4xx
          response code or an HTTP 5xx response code.

          When  curl  is about to retry a transfer, it will first wait one
          second and then for all forthcoming retries it will  double  the
          waiting  time until it reaches 10 minutes which then will be the
          delay between the rest of the retries.  By  using  --retry-delay
          you   disable  this  exponential  backoff  algorithm.  See  also
          --retry-max-time to limit the total time  allowed  for  retries.
          (Added in 7.12.3)

          If this option is used several times, the last one will be used.

   --retry-delay <seconds>
          Make  curl  sleep  this  amount of time before each retry when a
          transfer has failed with  a  transient  error  (it  changes  the
          default  backoff time algorithm between retries). This option is
          only interesting if --retry is also used. Setting this delay  to
          zero  will  make  curl  use the default backoff time.  (Added in
          7.12.3)

          If this option is used several times, the last one will be used.

   --retry-max-time <seconds>
          The retry timer is reset  before  the  first  transfer  attempt.
          Retries will be done as usual (see --retry) as long as the timer
          hasn't reached this given limit. Notice that if the timer hasn't
          reached  the  limit, the request will be made and while perform‐
          ing, it may take longer than this given time period. To limit  a
          single  request´s  maximum  time,  use -m, --max-time.  Set this
          option to zero to not timeout retries. (Added in 7.12.3)

          If this option is used several times, the last one will be used.

   -s, --silent
          Silent or quiet mode. Don't show progress meter  or  error  mes‐
          sages.   Makes  Curl mute. It will still output the data you ask
          for, potentially even to the terminal/stdout unless you redirect
          it.

   --sasl-ir
          Enable  initial  response  in  SASL  authentication.   (Added in
          7.31.0)

   --service-name <servicename>
          This option allows you to change the service name for SPNEGO.

          Examples:   --negotiate   --service-name   sockd    would    use
          sockd/server-name.  (Added in 7.43.0).

   -S, --show-error
          When  used  with  -s  it  makes curl show an error message if it
          fails.

   --ssl  (FTP, POP3, IMAP, SMTP) Try to use SSL/TLS for  the  connection.
          Reverts to a non-secure connection if the server doesn't support
          SSL/TLS.  See also --ftp-ssl-control and --ssl-reqd for  differ‐
          ent levels of encryption required. (Added in 7.20.0)

          This  option  was formerly known as --ftp-ssl (Added in 7.11.0).
          That option name can still be used but  will  be  removed  in  a
          future version.

   --ssl-reqd
          (FTP,  POP3,  IMAP,  SMTP)  Require  SSL/TLS for the connection.
          Terminates the connection if the server doesn't support SSL/TLS.
          (Added in 7.20.0)

          This  option  was  formerly  known  as  --ftp-ssl-reqd (added in
          7.15.5). That option name can still be used but will be  removed
          in a future version.

   --ssl-allow-beast
          (SSL)  This option tells curl to not work around a security flaw
          in the SSL3 and TLS1.0 protocols known as BEAST.  If this option
          isn't  used,  the  SSL  layer may use workarounds known to cause
          interoperability problems with some older  SSL  implementations.
          WARNING: this option loosens the SSL security, and by using this
          flag you ask for exactly that.  (Added in 7.25.0)

   --ssl-no-revoke
          (WinSSL) This option tells curl to disable  certificate  revoca‐
          tion checks.  WARNING: this option loosens the SSL security, and
          by using this flag you ask for exactly that.  (Added in 7.44.0)

   --socks4 <host[:port]>
          Use the specified SOCKS4 proxy. If the port number is not speci‐
          fied, it is assumed at port 1080. (Added in 7.15.2)

          This  option  overrides any previous use of -x, --proxy, as they
          are mutually exclusive.

          Since 7.21.7, this option is superfluous since you can specify a
          socks4 proxy with -x, --proxy using a socks4:// protocol prefix.

          If this option is used several times, the last one will be used.

   --socks4a <host[:port]>
          Use the specified SOCKS4a proxy. If the port number is not spec‐
          ified, it is assumed at port 1080. (Added in 7.18.0)

          This option overrides any previous use of -x, --proxy,  as  they
          are mutually exclusive.

          Since 7.21.7, this option is superfluous since you can specify a
          socks4a proxy with -x, --proxy using a socks4a:// protocol  pre‐
          fix.

          If this option is used several times, the last one will be used.

   --socks5-hostname <host[:port]>
          Use  the  specified  SOCKS5 proxy (and let the proxy resolve the
          host name). If the port number is not specified, it  is  assumed
          at port 1080. (Added in 7.18.0)

          This  option  overrides any previous use of -x, --proxy, as they
          are mutually exclusive.

          Since 7.21.7, this option is superfluous since you can specify a
          socks5 hostname proxy with -x, --proxy using a socks5h:// proto‐
          col prefix.

          If this option is used several times, the last one will be used.
          (This  option  was  previously  wrongly  documented  and used as
          --socks without the number appended.)

   --socks5 <host[:port]>
          Use the specified SOCKS5 proxy  -  but  resolve  the  host  name
          locally.  If  the port number is not specified, it is assumed at
          port 1080.

          This option overrides any previous use of -x, --proxy,  as  they
          are mutually exclusive.

          Since 7.21.7, this option is superfluous since you can specify a
          socks5 proxy with -x, --proxy using a socks5:// protocol prefix.

          If this option is used several times, the last one will be used.
          (This  option  was  previously  wrongly  documented  and used as
          --socks without the number appended.)

          This option (as well as --socks4) does not work with IPV6,  FTPS
          or LDAP.

   --socks5-gssapi-service <servicename>
          The default service name for a socks server is rcmd/server-fqdn.
          This option allows you to change it.

          Examples:  --socks5  proxy-name  --socks5-gssapi-service   sockd
          would  use sockd/proxy-name --socks5 proxy-name --socks5-gssapi-
          service sockd/real-name  would  use  sockd/real-name  for  cases
          where  the proxy-name does not match the principal name.  (Added
          in 7.19.4).

   --socks5-gssapi-nec
          As part of the GSS-API negotiation a protection mode is  negoti‐
          ated.  RFC  1961 says in section 4.3/4.4 it should be protected,
          but the NEC  reference  implementation  does  not.   The  option
          --socks5-gssapi-nec  allows the unprotected exchange of the pro‐
          tection mode negotiation. (Added in 7.19.4).

   --stderr <file>
          Redirect all writes to stderr to the specified file instead.  If
          the file name is a plain '-', it is instead written to stdout.

          If this option is used several times, the last one will be used.

   -t, --telnet-option <OPT=val>
          Pass options to the telnet protocol. Supported options are:

          TTYPE=<term> Sets the terminal type.

          XDISPLOC=<X display> Sets the X display location.

          NEW_ENV=<var,val> Sets an environment variable.

   -T, --upload-file <file>
          This  transfers  the  specified local file to the remote URL. If
          there is no file part in the specified URL, Curl will append the
          local file name. NOTE that you must use a trailing / on the last
          directory to really prove to Curl that there is no file name  or
          curl will think that your last directory name is the remote file
          name to use. That will most likely cause the upload operation to
          fail. If this is used on an HTTP(S) server, the PUT command will
          be used.

          Use the file name "-" (a single dash) to use stdin instead of  a
          given  file.   Alternately,  the file name "." (a single period)
          may be specified instead of "-" to  use  stdin  in  non-blocking
          mode  to  allow  reading  server  output  while  stdin  is being
          uploaded.

          You can specify one -T for each URL on the command line. Each -T
          + URL pair specifies what to upload and to where. curl also sup‐
          ports "globbing" of the -T argument, meaning that you can upload
          multiple  files  to  a single URL by using the same URL globbing
          style supported in the URL, like this:

          curl -T "{file1,file2}" http://www.uploadtothissite.com

          or even

          curl -T "img[1-1000].png" ftp://ftp.picturemania.com/upload/

   --tcp-nodelay
          Turn on the TCP_NODELAY option. See the curl_easy_setopt(3)  man
          page for details about this option. (Added in 7.11.2)

   --tftp-blksize <value>
          (TFTP) Set TFTP BLKSIZE option (must be >512). This is the block
          size that curl will try to use when transferring data to or from
          a TFTP server. By default 512 bytes will be used.

          If this option is used several times, the last one will be used.

          (Added in 7.20.0)

   --tlsauthtype <authtype>
          Set  TLS  authentication  type.  Currently,  the  only supported
          option is "SRP",  for  TLS-SRP  (RFC  5054).  If  --tlsuser  and
          --tlspassword  are specified but --tlsauthtype is not, then this
          option defaults to "SRP".  (Added in 7.21.4)

   --tlspassword <password>
          Set password for use with the TLS authentication  method  speci‐
          fied  with  --tlsauthtype.  Requires that --tlsuser also be set.
          (Added in 7.21.4)

   --tlsuser <user>
          Set username for use with the TLS authentication  method  speci‐
          fied  with  --tlsauthtype.  Requires  that --tlspassword also be
          set.  (Added in 7.21.4)

   --tlsv1.0
          (SSL) Forces curl to use TLS version 1.0 when negotiating with a
          remote TLS server.  (Added in 7.34.0)

   --tlsv1.1
          (SSL) Forces curl to use TLS version 1.1 when negotiating with a
          remote TLS server.  (Added in 7.34.0)

   --tlsv1.2
          (SSL) Forces curl to use TLS version 1.2 when negotiating with a
          remote TLS server.  (Added in 7.34.0)

   --tr-encoding
          (HTTP) Request a compressed Transfer-Encoding response using one
          of the algorithms curl supports, and uncompress the  data  while
          receiving it.

          (Added in 7.21.6)

   --trace <file>
          Enables  a  full  trace  dump of all incoming and outgoing data,
          including descriptive information, to the given output file. Use
          "-" as filename to have the output sent to stdout.

          This option overrides previous uses of -v, --verbose or --trace-
          ascii.

          If this option is used several times, the last one will be used.

   --trace-ascii <file>
          Enables a full trace dump of all  incoming  and  outgoing  data,
          including descriptive information, to the given output file. Use
          "-" as filename to have the output sent to stdout.

          This is very similar to --trace, but leaves out the hex part and
          only  shows  the ASCII part of the dump. It makes smaller output
          that might be easier to read for untrained humans.

          This option overrides previous uses of -v, --verbose or --trace.

          If this option is used several times, the last one will be used.

   --trace-time
          Prepends a time stamp to each trace or verbose  line  that  curl
          displays.  (Added in 7.14.0)

   --unix-socket <path>
          (HTTP) Connect through this Unix domain socket, instead of using
          the network. (Added in 7.40.0)

   -u, --user <user:password>
          Specify the user name and password to use for server authentica‐
          tion. Overrides -n, --netrc and --netrc-optional.

          If  you  simply  specify  the  user name, curl will prompt for a
          password.

          The user name and passwords are split up  on  the  first  colon,
          which  makes  it impossible to use a colon in the user name with
          this option. The password can, still.

          When using Kerberos V5 with a Windows based  server  you  should
          include  the  Windows domain name in the user name, in order for
          the server to successfully obtain  a  Kerberos  Ticket.  If  you
          don't then the initial authentication handshake may fail.

          When  using  NTLM,  the user name can be specified simply as the
          user name, without the domain, if there is a single  domain  and
          forest in your setup for example.

          To  specify  the domain name use either Down-Level Logon Name or
          UPN (User Principal Name) formats. For example, EXAMPLE\user and
          [email protected] respectively.

          If  you  use a Windows SSPI-enabled curl binary and perform Ker‐
          beros V5, Negotiate, NTLM or Digest authentication then you  can
          tell  curl  to select the user name and password from your envi‐
          ronment by specifying a single colon with this option: "-u :".

          If this option is used several times, the last one will be used.

   -U, --proxy-user <user:password>
          Specify the user name and password to use for proxy  authentica‐
          tion.

          If  you  use  a  Windows  SSPI-enabled curl binary and do either
          Negotiate or NTLM authentication  then  you  can  tell  curl  to
          select the user name and password from your environment by spec‐
          ifying a single colon with this option: "-U :".

          If this option is used several times, the last one will be used.

   --url <URL>
          Specify a URL to fetch. This option is  mostly  handy  when  you
          want to specify URL(s) in a config file.

          If  the given URL is missing a scheme name (such as "http://" or
          "ftp://" etc) then curl will make a guess based on the host.  If
          the  outermost  sub-domain  name  matches DICT, FTP, IMAP, LDAP,
          POP3 or SMTP then that protocol will  be  used,  otherwise  HTTP
          will be used. Since 7.45.0 guessing can be disabled by setting a
          default protocol, see --proto-default for details.

          This option may be used any number of times.  To  control  where
          this  URL  is written, use the -o, --output or the -O, --remote-
          name options.

   -v, --verbose
          Be more  verbose/talkative  during  the  operation.  Useful  for
          debugging  and  seeing  what's going on "under the hood". A line
          starting with '>' means "header data" sent by  curl,  '<'  means
          "header  data"  received by curl that is hidden in normal cases,
          and a line starting with '*' means additional info  provided  by
          curl.

          Note  that  if  you  only  want  HTTP headers in the output, -i,
          --include might be the option you're looking for.

          If you think this option still doesn't give you enough  details,
          consider using --trace or --trace-ascii instead.

          This option overrides previous uses of --trace-ascii or --trace.

          Use -s, --silent to make curl quiet.

   -w, --write-out <format>
          Make curl display information on stdout after a completed trans‐
          fer. The format is a string that may contain  plain  text  mixed
          with  any  number of variables. The format can be specified as a
          literal "string", or you can have curl read the  format  from  a
          file  with  "@filename" and to tell curl to read the format from
          stdin you write "@-".

          The variables present in the output format will  be  substituted
          by  the  value or text that curl thinks fit, as described below.
          All variables are specified as %{variable_name} and to output  a
          normal  % you just write them as %%. You can output a newline by
          using \n, a carriage return with \r and a tab space with \t.

          NOTE: The %-symbol is a special symbol in the win32-environment,
          where  all  occurrences  of  %  must  be doubled when using this
          option.

          The variables available are:

          content_type   The Content-Type of the  requested  document,  if
                         there was any.

          filename_effective
                         The  ultimate  filename  that curl writes out to.
                         This is only meaningful if curl is told to  write
                         to  a  file  with  the  --remote-name or --output
                         option. It's most useful in combination with  the
                         --remote-header-name option. (Added in 7.25.1)

          ftp_entry_path The initial path curl ended up in when logging on
                         to the remote FTP server. (Added in 7.15.4)

          http_code      The numerical response code that was found in the
                         last  retrieved  HTTP(S)  or  FTP(s) transfer. In
                         7.18.2 the alias response_code was added to  show
                         the same info.

          http_connect   The  numerical  code  that  was found in the last
                         response  (from  a  proxy)  to  a  curl   CONNECT
                         request. (Added in 7.12.4)

          local_ip       The  IP  address  of  the  local  end of the most
                         recently done connection - can be either IPv4  or
                         IPv6 (Added in 7.29.0)

          local_port     The  local  port number of the most recently done
                         connection (Added in 7.29.0)

          num_connects   Number of new connects made in the recent  trans‐
                         fer. (Added in 7.12.3)

          num_redirects  Number  of  redirects  that  were followed in the
                         request. (Added in 7.12.3)

          redirect_url   When an HTTP request was made without -L to  fol‐
                         low redirects, this variable will show the actual
                         URL a redirect  would  take  you  to.  (Added  in
                         7.18.2)

          remote_ip      The  remote  IP address of the most recently done
                         connection - can be either IPv4 or IPv6 (Added in
                         7.29.0)

          remote_port    The  remote port number of the most recently done
                         connection (Added in 7.29.0)

          size_download  The total amount of bytes that were downloaded.

          size_header    The total amount of bytes of the downloaded head‐
                         ers.

          size_request   The  total  amount of bytes that were sent in the
                         HTTP request.

          size_upload    The total amount of bytes that were uploaded.

          speed_download The average download speed that curl measured for
                         the complete download. Bytes per second.

          speed_upload   The  average  upload speed that curl measured for
                         the complete upload. Bytes per second.

          ssl_verify_result
                         The result of the SSL peer certificate  verifica‐
                         tion that was requested. 0 means the verification
                         was successful. (Added in 7.19.0)

          time_appconnect
                         The time, in seconds,  it  took  from  the  start
                         until  the  SSL/SSH/etc  connect/handshake to the
                         remote host was completed. (Added in 7.19.0)

          time_connect   The time, in seconds,  it  took  from  the  start
                         until  the  TCP  connect  to  the remote host (or
                         proxy) was completed.

          time_namelookup
                         The time, in seconds,  it  took  from  the  start
                         until the name resolving was completed.

          time_pretransfer
                         The  time,  in  seconds,  it  took from the start
                         until the file transfer was just about to  begin.
                         This includes all pre-transfer commands and nego‐
                         tiations that are specific to the particular pro‐
                         tocol(s) involved.

          time_redirect  The time, in seconds, it took for all redirection
                         steps include name lookup,  connect,  pretransfer
                         and  transfer  before  the  final transaction was
                         started. time_redirect shows the complete  execu‐
                         tion  time  for  multiple redirections. (Added in
                         7.12.3)

          time_starttransfer
                         The time, in seconds,  it  took  from  the  start
                         until  the first byte was just about to be trans‐
                         ferred. This includes time_pretransfer  and  also
                         the  time  the  server  needed  to  calculate the
                         result.

          time_total     The total time, in seconds, that the full  opera‐
                         tion lasted. The time will be displayed with mil‐
                         lisecond resolution.

          url_effective  The URL that was fetched last. This is most mean‐
                         ingful  if  you've  told curl to follow location:
                         headers.

          If this option is used several times, the last one will be used.

   -x, --proxy <[protocol://][user:password@]proxyhost[:port]>
          Use the specified proxy.

          The proxy string can be specified with a protocol://  prefix  to
          specify  alternative proxy protocols. Use socks4://, socks4a://,
          socks5:// or socks5h:// to request the specific SOCKS version to
          be  used.  No protocol specified, http:// and all others will be
          treated as HTTP proxies. (The protocol support was added in curl
          7.21.7)

          If  the  port number is not specified in the proxy string, it is
          assumed to be 1080.

          This option overrides existing environment  variables  that  set
          the  proxy  to use. If there's an environment variable setting a
          proxy, you can set proxy to "" to override it.

          All operations that are performed over an HTTP proxy will trans‐
          parently  be  converted  to HTTP. It means that certain protocol
          specific operations might not be available. This is not the case
          if you can tunnel through the proxy, as one with the -p, --prox‐
          ytunnel option.

          User and password that might be provided in the proxy string are
          URL  decoded by curl. This allows you to pass in special charac‐
          ters such as @ by using %40 or pass in a colon with %3a.

          The proxy host can be specified the exact same way as the  proxy
          environment  variables,  including the protocol prefix (http://)
          and the embedded user + password.

          If this option is used several times, the last one will be used.

   -X, --request <command>
          (HTTP) Specifies a custom request method to use when communicat‐
          ing  with the HTTP server.  The specified request method will be
          used instead of the method otherwise  used  (which  defaults  to
          GET).  Read  the HTTP 1.1 specification for details and explana‐
          tions. Common additional HTTP requests include PUT  and  DELETE,
          but related technologies like WebDAV offers PROPFIND, COPY, MOVE
          and more.

          Normally you don't need this option. All  sorts  of  GET,  HEAD,
          POST and PUT requests are rather invoked by using dedicated com‐
          mand line options.

          This option only changes  the  actual  word  used  in  the  HTTP
          request,  it does not alter the way curl behaves. So for example
          if you want to make a proper HEAD request, using  -X  HEAD  will
          not suffice. You need to use the -I, --head option.

          The method string you set with -X will be used for all requests,
          which if you for example use -L, --location may cause unintended
          side-effects  when  curl doesn't change request method according
          to the HTTP 30x response codes - and similar.

          (FTP) Specifies a custom FTP command to use instead of LIST when
          doing file lists with FTP.

          (POP3) Specifies a custom POP3 command to use instead of LIST or
          RETR. (Added in 7.26.0)

          (IMAP) Specifies a custom IMAP command to use instead  of  LIST.
          (Added in 7.30.0)

          (SMTP) Specifies a custom SMTP command to use instead of HELP or
          VRFY. (Added in 7.34.0)

          If this option is used several times, the last one will be used.

   --xattr
          When saving output to a file, this option tells  curl  to  store
          certain  file  metadata  in extended file attributes. Currently,
          the URL is stored in the xdg.origin.url attribute and, for HTTP,
          the  content  type  is stored in the mime_type attribute. If the
          file system does not support extended attributes, a  warning  is
          issued.

   -y, --speed-time <time>
          If a download is slower than speed-limit bytes per second during
          a speed-time period, the download gets aborted. If speed-time is
          used, the default speed-limit will be 1 unless set with -Y.

          This  option  controls  transfers  and thus will not affect slow
          connects etc. If this is a concern for you, try  the  --connect-
          timeout option.

          If this option is used several times, the last one will be used.

   -Y, --speed-limit <speed>
          If a download is slower than this given speed (in bytes per sec‐
          ond) for speed-time seconds it gets aborted. speed-time  is  set
          with -y and is 30 if not set.

          If this option is used several times, the last one will be used.

   -z, --time-cond <date expression>|<file>
          (HTTP/FTP)  Request a file that has been modified later than the
          given time and date, or one that has been modified  before  that
          time.  The <date expression> can be all sorts of date strings or
          if it doesn't match any internal ones, it is taken as a filename
          and  tries  to  get  the  modification  date (mtime) from <file>
          instead. See the curl_getdate(3) man pages for  date  expression
          details.

          Start the date expression with a dash (-) to make it request for
          a document that is older than the given date/time, default is  a
          document that is newer than the specified date/time.

          If this option is used several times, the last one will be used.

   -h, --help
          Usage  help.  This lists all current command line options with a
          short description.

   -M, --manual
          Manual. Display the huge help text.

   -V, --version
          Displays information about curl and the libcurl version it uses.

          The first line includes the full version of  curl,  libcurl  and
          other 3rd party libraries linked with the executable.

          The  second  line (starts with "Protocols:") shows all protocols
          that libcurl reports to support.

          The third line (starts with "Features:") shows specific features
          libcurl reports to offer. Available features include:

          IPv6   You can use IPv6 with this.

          krb4   Krb4 for FTP is supported.

          SSL    SSL  versions of various protocols are supported, such as
                 HTTPS, FTPS, POP3S and so on.

          libz   Automatic decompression of compressed files over HTTP  is
                 supported.

          NTLM   NTLM authentication is supported.

          Debug  This  curl  uses a libcurl built with Debug. This enables
                 more error-tracking and memory debugging etc.  For  curl-
                 developers only!

          AsynchDNS
                 This  curl  uses asynchronous name resolves. Asynchronous
                 name resolves can be done using either the c-ares or  the
                 threaded resolver backends.

          SPNEGO SPNEGO authentication is supported.

          Largefile
                 This curl supports transfers of large files, files larger
                 than 2GB.

          IDN    This curl supports IDN - international domain names.

          GSS-API
                 GSS-API is supported.

          SSPI   SSPI is supported.

          TLS-SRP
                 SRP (Secure Remote Password) authentication is  supported
                 for TLS.

          HTTP2  HTTP/2 support has been built-in.

          Metalink
                 This  curl  supports  Metalink (both version 3 and 4 (RFC
                 5854)), which describes mirrors and  hashes.   curl  will
                 use mirrors for failover if there are errors (such as the
                 file or server not being available).

FILES ~/.curlrc Default config file, see -K, --config for details.

ENVIRONMENT The environment variables can be specified in lower case or upper case. The lower case version has precedence. http_proxy is an exception as it is only available in lower case.

   Using an environment variable to set the proxy has the same  effect  as
   using the --proxy option.

   http_proxy [protocol://]<host>[:port]
          Sets the proxy server to use for HTTP.

   HTTPS_PROXY [protocol://]<host>[:port]
          Sets the proxy server to use for HTTPS.

   [url-protocol]_PROXY [protocol://]<host>[:port]
          Sets  the proxy server to use for [url-protocol], where the pro‐
          tocol is a protocol that curl supports and  as  specified  in  a
          URL. FTP, FTPS, POP3, IMAP, SMTP, LDAP etc.

   ALL_PROXY [protocol://]<host>[:port]
          Sets  the  proxy  server to use if no protocol-specific proxy is
          set.

   NO_PROXY <comma-separated list of hosts>
          list of host names that shouldn't go through any proxy.  If  set
          to a asterisk '*' only, it matches all hosts.

PROXY PROTOCOL PREFIXES Since curl version 7.21.7, the proxy string may be specified with a protocol:// prefix to specify alternative proxy protocols.

   If no protocol is specified in  the  proxy  string  or  if  the  string
   doesn't  match  a  supported  one, the proxy will be treated as an HTTP
   proxy.

   The supported proxy protocol prefixes are as follows:

   socks4://
          Makes it the equivalent of --socks4

   socks4a://
          Makes it the equivalent of --socks4a

   socks5://
          Makes it the equivalent of --socks5

   socks5h://
          Makes it the equivalent of --socks5-hostname

EXIT CODES There are a bunch of different error codes and their corresponding error messages that may appear during bad conditions. At the time of this writing, the exit codes are:

   1      Unsupported protocol. This build of curl has no support for this
          protocol.

   2      Failed to initialize.

   3      URL malformed. The syntax was not correct.

   4      A  feature  or  option  that  was  needed to perform the desired
          request was not enabled or was  explicitly  disabled  at  build-
          time.  To  make  curl able to do this, you probably need another
          build of libcurl!

   5      Couldn't resolve proxy.  The  given  proxy  host  could  not  be
          resolved.

   6      Couldn't resolve host. The given remote host was not resolved.

   7      Failed to connect to host.

   8      FTP  weird  server  reply.  The  server  sent data curl couldn't
          parse.

   9      FTP access denied. The server denied login or denied  access  to
          the  particular  resource or directory you wanted to reach. Most
          often you tried to change to a directory that doesn't  exist  on
          the server.

   11     FTP  weird PASS reply. Curl couldn't parse the reply sent to the
          PASS request.

   13     FTP weird PASV reply, Curl couldn't parse the reply sent to  the
          PASV request.

   14     FTP  weird  227  format.  Curl  couldn't  parse the 227-line the
          server sent.

   15     FTP can't get host. Couldn't resolve the host IP we got  in  the
          227-line.

   17     FTP  couldn't  set  binary.  Couldn't  change transfer method to
          binary.

   18     Partial file. Only a part of the file was transferred.

   19     FTP couldn't download/access the given file, the RETR (or  simi‐
          lar) command failed.

   21     FTP quote error. A quote command returned error from the server.

   22     HTTP  page  not  retrieved.  The  requested url was not found or
          returned another error with the HTTP error  code  being  400  or
          above. This return code only appears if -f, --fail is used.

   23     Write  error.  Curl couldn't write data to a local filesystem or
          similar.

   25     FTP couldn't STOR file. The server denied  the  STOR  operation,
          used for FTP uploading.

   26     Read error. Various reading problems.

   27     Out of memory. A memory allocation request failed.

   28     Operation  timeout.  The  specified  time-out period was reached
          according to the conditions.

   30     FTP PORT failed. The PORT command failed. Not  all  FTP  servers
          support  the  PORT  command,  try  doing  a  transfer using PASV
          instead!

   31     FTP couldn't use REST. The REST command failed. This command  is
          used for resumed FTP transfers.

   33     HTTP range error. The range "command" didn't work.

   34     HTTP post error. Internal post-request generation error.

   35     SSL connect error. The SSL handshaking failed.

   36     FTP  bad  download  resume. Couldn't continue an earlier aborted
          download.

   37     FILE couldn't read file. Failed to open the file. Permissions?

   38     LDAP cannot bind. LDAP bind operation failed.

   39     LDAP search failed.

   41     Function not found. A required LDAP function was not found.

   42     Aborted by callback. An application told curl to abort the oper‐
          ation.

   43     Internal error. A function was called with a bad parameter.

   45     Interface  error.  A  specified  outgoing interface could not be
          used.

   47     Too many redirects. When following redirects, curl hit the maxi‐
          mum amount.

   48     Unknown  option  specified  to  libcurl. This indicates that you
          passed a weird option to curl that was passed on to libcurl  and
          rejected. Read up in the manual!

   49     Malformed telnet option.

   51     The peer's SSL certificate or SSH MD5 fingerprint was not OK.

   52     The  server  didn't  reply anything, which here is considered an
          error.

   53     SSL crypto engine not found.

   54     Cannot set SSL crypto engine as default.

   55     Failed sending network data.

   56     Failure in receiving network data.

   58     Problem with the local certificate.

   59     Couldn't use specified SSL cipher.

   60     Peer certificate cannot be authenticated with known CA  certifi‐
          cates.

   61     Unrecognized transfer encoding.

   62     Invalid LDAP URL.

   63     Maximum file size exceeded.

   64     Requested FTP SSL level failed.

   65     Sending the data requires a rewind that failed.

   66     Failed to initialise SSL Engine.

   67     The  user  name,  password, or similar was not accepted and curl
          failed to log in.

   68     File not found on TFTP server.

   69     Permission problem on TFTP server.

   70     Out of disk space on TFTP server.

   71     Illegal TFTP operation.

   72     Unknown TFTP transfer ID.

   73     File already exists (TFTP).

   74     No such user (TFTP).

   75     Character conversion failed.

   76     Character conversion functions required.

   77     Problem with reading the SSL CA cert (path? access rights?).

   78     The resource referenced in the URL does not exist.

   79     An unspecified error occurred during the SSH session.

   80     Failed to shut down the SSL connection.

   82     Could not load CRL file,  missing  or  wrong  format  (added  in
          7.19.0).

   83     Issuer check failed (added in 7.19.0).

   84     The FTP PRET command failed

   85     RTSP: mismatch of CSeq numbers

   86     RTSP: mismatch of Session Identifiers

   87     unable to parse FTP file list

   88     FTP chunk callback reported error

   89     No connection available, the session will be queued

   90     SSL public key does not matched pinned public key

   XX     More error codes will appear here in future releases. The exist‐
          ing ones are meant to never change.

AUTHORS / CONTRIBUTORS Daniel Stenberg is the main author, but the whole list of contributors is found in the separate THANKS file.

WWW http://curl.haxx.se

FTP ftp://ftp.sunet.se/pub/www/utilities/curl/

SEE ALSO ftp(1), wget(1)

Curl 7.40.0 30 Nov 2014 curl(1)

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