Man Linux: Main Page and Category List

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 (HTTP, HTTPS, FTP, FTPS,  SCP,  SFTP,  TFTP,  DICT,
       TELNET,  LDAP  or  FILE).  The command is designed to work without user
       interaction.

       curl offers a  busload  of  useful  tricks  like  proxy  support,  user
       authentication,  FTP  upload, HTTP post, SSL connections, cookies, file
       transfer resume 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
       description 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

       No nesting of the sequences is supported at the moment, 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.

       Since curl 7.15.1 you can also specify a step counter for  the  ranges,
       so that you can get every Nth number or letter:

        http://www.numericals.com/file[1-100:10].txt
        http://www.letters.com/file[a-z:2].txt

       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
       example, 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
       connects / 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.

       However,  since  curl displays this data to the terminal by default, 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

       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.)

       -a/--append
              (FTP/SFTP) When used in an upload, this will tell curl to append
              to the target file  instead  of  overwriting  it.  If  the  file
              doesn’t  exist,  it  will  be  created.   Note that this flag is
              ignored by some SSH 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 set more than once, the last one will  be  the
              one that’s 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
              supposedly  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
              filename 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 parser" 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.

              NOTE that the file specified with -b/--cookie is  only  used  as
              input.  No cookies will be stored in the file. To store cookies,
              use the -c/--cookie-jar option or you could even save  the  HTTP
              headers to a file using -D/--dump-header!

              If  this  option is set more than once, the last one will be the
              one that’s used.

       -B/--use-ascii
              Enable ASCII transfer when using FTP or LDAP. 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. 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).

       --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:
              http://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:
              http://directory.fedora.redhat.com/docs/mod_nss.html#Directives

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

       --compressed
              (HTTP) Request a compressed response using one of the algorithms
              libcurl supports, and return 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 the connection to the
              server to take.  This only limits  the  connection  phase,  once
              curl  has  connected this option is of no more use. See also the
              -m/--max-time option.

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

       -c/--cookie-jar <file name>
              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  file  will  be
              written. 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.

              NOTE 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
              feedback you get about this possibly lethal situation.

              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.

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

       --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.  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
              command  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.  The contents of the file must  already  be
              URL-encoded.  Multiple files can also be specified. Posting data
              from a file named  ’foobar’  would  thus  be  done  with  --data
              @foobar.

       --data-binary <data>
              (HTTP)  This  posts  data  exactly  as  specified  with no extra
              processing 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 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-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.

       --digest
              (HTTP)  Enables  HTTP   Digest   authentication.   This   is   a
              authentication  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, the following  occurrences
              make no difference.

       --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
              extensions 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.

              Since  curl 7.19.0, --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.

              Since  curl 7.19.0, --epsv can be used to explicitly enable EPRT
              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.

       -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 a 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  however  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.

       -e/--referer <URL>
              (HTTP)  Sends the "Referer 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
              follows  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.

       --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
              useful 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.

       -E/--cert <certificate[:password]>
              (SSL) Tells curl to use  the  specified  certificate  file  when
              getting  a  file  with HTTPS or FTPS. The certificate must be in
              PEM format.  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  private
              certificate  concatenated!  See --cert and --key to specify them
              independently.

              If curl is built against the NSS SSL library  then  this  option
              tells 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
              (libnsspem.so) is available then PEM files may be loaded.

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

       --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
              directory 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 then this option
              tells curl the nickname of the CA 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
              (libnsspem.so) is available then PEM files may be loaded.

              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. The certificates must be in PEM format, and the
              directory must have been processed using  the  c_rehash  utility
              supplied  with  openssl.  Using  --capath can allow curl to make
              SSL-connections much more efficiently than using --cacert if the
              --cacert file contains many CA certificates.

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

       -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 a  HTTP  server  fails  to
              deliver  a  document,  it  returns  an  HTML document stating so
              (which often also  describes  why  and  more).  This  flag  will
              prevent 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).

       --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  twice,  the second will override the
              previous use.

       --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 a
              FTP(S)  server.  The  method  argument  should  be  one  of  the
              following 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  RFC1738 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
                     commands. 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 conection. 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, the following occurrences
              make no difference. 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-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-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)

       --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
              different levels of encryption required. (Added in 7.20.0)

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

       --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
              support SSL/TLS.  (Added in 7.16.0)

       --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)  and  that  can  still  be used but will be removed in a
              future version.

       --ftp-ssl-ccc
              (FTP) Use CCC (Clear Command Channel)  Shuts  down  the  SSL/TLS
              layer  after  authenticating.  The  rest  of the control channel
              communication will be unencrypted. This allows  NAT  routers  to
              follow  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)

       -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 RFC2388.
              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
              ’password’ 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  the file’s content from stdin instead of a file, use -
              where the file name should’ve been. This goes for both @  and  <
              constructs.

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

              curl -F "web=@index.html;type=text/html" url.com

              or

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

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

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

              See further examples and details in the MANUAL.

              This option can be used multiple times.

       --form-string <name=string>
              (HTTP)  Similar  to  --form except that the value string for the
              named  parameter  is  used  literally.  Leading  ’@’   and   ’<’
              characters, and the ’;type=’ string in the value have no special
              meaning. 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  or  --data-binary  to  be  used in a 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, the following  occurrences
              make  no  difference. This is because undoing a GET doesn’t make
              sense, but you  should  then  instead  enforce  the  alternative
              method you prefer.

       -h/--help
              Usage help.

       -H/--header <header>
              (HTTP)  Extra  header  to  use  when getting a web page. 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 perfectly well
              what you’re  doing.  Remove  an  internal  header  by  giving  a
              replacement  without  content on the right side of the colon, as
              in: -H "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.

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

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

       --hostpubmd5 <md5>
              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.  This option is only for SCP and SFTP transfers.
              (Added in 7.17.1)

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

       -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...

       --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.

       -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 a FTP or FILE file, curl displays
              the file size and last modification time only.

       -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.

       -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

       --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 multiple times, the last occurrence  sets
              the amount.

       --key <key>
              (SSL/SSH)  Private  key  file  name.  Allows you to provide your
              private key in this separate file.

              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
              provided 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 or GSSAPI
              (GSS-Negotiate)  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.

       -K/--config <config file>
              Specify which config file  to  read  curl  arguments  from.  The
              config  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 config file line, separated by whitespace,
              colon,  the equals sign or any combination thereof (however, the
              preferred separator is the equals sign). 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/"

              Long  option  names  can  optionally be given in the config file
              without the initial double dashes.

              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
              ’%USERPROFILE%\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.

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

              NOTE:  this  does  not  properly  support  -F and the sending of
              multipart formposts, so in those cases the output  program  will
              be  missing  necessary  calls  to  curl_formadd(3), and possibly
              more.

              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. This
              feature is useful if you have a limited pipe and you’d like your
              transfer not to use your entire bandwidth.

              The  given speed is measured in bytes/second, unless a suffix is
              appended.  Appending  ’k’  or  ’K’  will  count  the  number  as
              kilobytes,  ’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.

       -l/--list-only
              (FTP) When listing an FTP directory, this switch forces a  name-
              only  view.   Especially useful if you want to machine-parse the
              contents of an FTP directory since  the  normal  directory  view
              doesn’t use a standard look or format.

              This  option  causes  an  FTP NLST command to be sent.  Some FTP
              servers list only files in their response to NLST; they  do  not
              include subdirectories and symbolic links.

       --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)

       -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
              --location-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.

       --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).

       --mail-rcpt <address>
              (SMTP)  Specify  a single address that the given mail should get
              sent to. This option can be used multiple times to specify  many
              recipients.

              (Added in 7.20.0)

       --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
              transfer ends up  being  larger  than  this  given  limit.  This
              concerns both FTP and HTTP transfers.

       -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
              hanging for hours due to slow networks or links going down.  See
              also the --connect-timeout option.

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

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

       -n/--netrc
              Makes  curl  scan  the  .netrc  (_netrc  on Windows) file in the
              user’s home directory for  login  name  and  password.  This  is
              typically  used  for  FTP  on UNIX. If used with HTTP, curl will
              enable user authentication. See netrc(4) or 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-readable). 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

       --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  GSS-Negotiate authentication. The GSS-Negotiate
              method was designed by  Microsoft  and  is  used  in  their  web
              applications.  It  is primarily meant as a support for Kerberos5
              authentication  but  may  be  also  used  along   with   another
              authentication  method.  For  more  information  see  IETF draft
              draft-brezak-spnego-http-04.txt.

              If you want to enable Negotiate for your  proxy  authentication,
              then use --proxy-negotiate.

              This  option  requires a library built with GSSAPI support. This
              is not very common. Use -V/--version  to  see  if  your  version
              supports GSS-Negotiate.

              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, the following  occurrences
              make no difference.

       -N/--no-buffer
              Disables  the  buffering  of  the  output stream. In normal work
              situations, 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.

       --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
              people 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
              authentication 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, the following  occurrences
              make no difference.

       -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
              directories 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.

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

       --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)

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

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

       --post301
              Tells curl to respect  RFC  2616/10.3.2  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
              redirection.   This   option   is  meaningful  only  when  using
              -L/--location (Added in 7.17.1)

       --post302
              Tells curl to respect  RFC  2616/10.3.2  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
              redirection.   This   option   is  meaningful  only  when  using
              -L/--location (Added in 7.19.1)

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

              +  Permit   this  protocol  in  addition  to  protocols  already
                 permitted (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
                 permitted),  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
              protocols,  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-redir <protocols>
              Tells curl to use the listed protocols  after  a  redirect.  See
              --proto for how protocols are represented.

              (Added in 7.20.2)

       --proxy-anyauth
              Tells  curl  to  pick  a  suitable  authentication  method  when
              communicating 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   authentication   when
              communicating with the given proxy. Use --negotiate for enabling
              HTTP Negotiate 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.

       --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.

       -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
              tunnel  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.

       --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.

       -P/--ftp-port <address>
              (FTP)   Reverses   the  default  initiator/listener  roles  when
              connecting 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.

       -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
              libcurl has changed  the  working  directory,  just  before  the
              transfer command(s), prefix the command with a ’+’ (this is only
              supported for FTP). You may specify any number of  commands.  If
              the  server  returns failure for one of the commands, the entire
              operation will be aborted. You must send  syntactically  correct
              FTP  commands  as  RFC959  defines to FTP servers, or one of the
              commands listed below to SFTP servers.  This option can be  used
              multiple times.

              SFTP  is  a  binary protocol. Unlike for FTP, libcurl interprets
              SFTP  quote  commands  before  sending  them  to   the   server.
              Following is the list of all supported SFTP quote commands:

              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
                     operand. 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
                     location.

              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
                     current 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
                     operand.

              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.

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

       -r/--range <range>
              (HTTP/FTP/SFTP/FILE)  Retrieve  a  byte  range  (i.e  a  partial
              document)  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(*)(H)

              500-700,600-799
                        specifies 300 bytes from offset 500(H)

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

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

       Only  digit characters (0-9) are valid in the ’start’ and ’stop’ fields
       of the ’start-stop’ range syntax. If a non-digit character is given  in
       the  range, the server’s response will be unspecified, 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.

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

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

       --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  multiple  times,  the  last  occurrence
              decide the amount.

       --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  multiple  times,  the  last  occurrence
              determines the amount.

       --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
              performing,  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  multiple  times, the last occurrence
              determines the amount.

       -s/--silent
              Silent or  quiet  mode.  Don’t  show  progress  meter  or  error
              messages.  Makes Curl mute.

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

       --socks4 <host[:port]>
              Use the specified SOCKS4  proxy.  If  the  port  number  is  not
              specified, 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.

              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
              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.

              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.

              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.

              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 princpal name.
               (Added in 7.19.4).

       --socks5-gssapi-nec
              As   part  of  the  gssapi  negotiation  a  protection  mode  is
              negotiated. The rfc1961 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 protection 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.
              This  option  has no point when you’re using a shell with decent
              redirecting capabilities.

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

       --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)

       -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.

       --tftp-blksize <value>
              (TFTP) Set TFTP BLKSIZE option (must be >512). This is the block
              size  that curl will try to use when tranferring 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)

       -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 a 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
              supports "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/

       --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)

       -u/--user <user:password>
              Specify   the   user   name  and  password  to  use  for  server
              authentication. Overrides -n/--netrc and --netrc-optional.

              If you just give the user name (without entering a  colon)  curl
              will prompt for a password.

              If   you   use   an   SSPI-enabled   curl  binary  and  do  NTLM
              authentication, you can force curl to pick up the user name  and
              password  from  your  environment  by simply 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
              authentication.

              If  you  use  an  SSPI-enabled   curl   binary   and   do   NTLM
              authentication,  you can force curl to pick up the user name and
              password from your environment by  simply  specifying  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.

              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
              Makes  the  fetching  more  verbose/talkative. Mostly useful for
              debugging. 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.

       -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    HTTPS and FTPS are supported.

              libz   Automatic decompression of compressed files over HTTP  is
                     supported.

              NTLM   NTLM authentication is supported.

              GSS-Negotiate
                     Negotiate authentication and krb5 for FTP 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.

              SPNEGO SPNEGO Negotiate authentication is supported.

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

              IDN    This curl supports IDN - international domain names.

              SSPI   SSPI is supported. If you use NTLM and set a  blank  user
                     name,  curl  will authenticate with your current user and
                     password.

       -w/--write-out <format>
              Defines  what  to  display  on  stdout  after  a  completed  and
              successful  operation.  The  format is a string that may contain
              plain text mixed with any number of variables. The string can be
              specified  as  "string",  to get read from a particular file you
              specify it "@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 at this point are:

              url_effective  The  URL  that  was  fetched  last.  This is most
                             meaningful  if  you’ve  told   curl   to   follow
                             location: headers.

              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)

              time_total     The  total  time,  in  seconds,  that  the   full
                             operation lasted. The time will be displayed with
                             millisecond resolution.

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

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

              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_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
                             negotiations that are specific to the  particular
                             protocol(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
                             execution  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
                             transferred. This includes  time_pretransfer  and
                             also  the time the server needed to calculate the
                             result.

              size_download  The total amount of bytes that were downloaded.

              size_upload    The total amount of bytes that were uploaded.

              size_header    The total  amount  of  bytes  of  the  downloaded
                             headers.

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

              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.

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

              num_connects   Number   of  new  connects  made  in  the  recent
                             transfer. (Added in 7.12.3)

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

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

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

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

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

       -x/--proxy <proxyhost[:port]>
              Use the  specified  HTTP  proxy.  If  the  port  number  is  not
              specified, it is assumed at port 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.

              Note  that  all  operations that are performed over a HTTP proxy
              will transparently 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 done  with  the
              -p/--proxytunnel option.

              Starting  with 7.14.1, 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
              communicating  with the HTTP server.  The specified request will
              be used instead of the method otherwise used (which defaults  to
              GET).   Read   the   HTTP  1.1  specification  for  details  and
              explanations. Common additional HTTP requests  include  PUT  and
              DELETE,  but  related  technologies like WebDAV offers PROPFIND,
              COPY, MOVE and more.

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

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

       -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
              second) 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>
              (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 tries to get the time
              from a given file name  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.

       --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
              limitless.

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

       -0/--http1.0
              (HTTP)  Forces curl to issue its requests using HTTP 1.0 instead
              of using its internally preferred: HTTP 1.1.

       -1/--tlsv1
              (SSL) Forces curl to use TLS version 1 when negotiating  with  a
              remote TLS server.

       -2/--sslv2
              (SSL)  Forces  curl to use SSL version 2 when negotiating with a
              remote SSL server.

       -3/--sslv3
              (SSL) Forces curl to use SSL version 3 when negotiating  with  a
              remote SSL server.

       -4/--ipv4
              If  libcurl  is  capable  of resolving an address to multiple IP
              versions (which it is if it is IPv6-capable), this option  tells
              libcurl to resolve names to IPv4 addresses only.

       -6/--ipv6
              If  libcurl  is  capable  of resolving an address to multiple IP
              versions (which it is if it is IPv6-capable), this option  tells
              libcurl to resolve names to IPv6 addresses only.

       -#/--progress-bar
              Make curl display progress information as a progress bar instead
              of the default statistics.

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.

       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.

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

       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.

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.

       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
              similar) 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
              operation.

       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
              maximum amount.

       48     Unknown TELNET option specified.

       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
              certificates.

       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).

       XX     More  error  codes  will  appear  here  in  future releases. The
              existing 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)