Provided by: libcoap2-bin_4.2.1-1build1_amd64 bug


       coap-client - CoAP Client based on libcoap


       coap-client [-a addr] [-b [num,]size] [-e text] [-f file] [-l loss] [-m method] [-o file]
       [-p port] [-r] [-s duration] [-t type] [-v num] [-A type] [-B seconds] [-K interval] [-N]
       [-O num,text] [-P addr[:port]] [-T token] [-U] [[-k key] [-u user]] [[-c certfile] [-C
       cafile] [-R root_cafile]] URI


       coap-client is a CoAP client to communicate with 6LoWPAN devices via the protocol CoAP
       (RFC 7252) using the URI given as argument on the command line. The URI must have the
       scheme coap, coap+tcp, coaps or coaps+tcp. coaps and coaps+tcp are only supported when
       coap-client is built with support for secure (D)TLS communication.

       If coaps or coap+tcp is being used, provided the CoAP server supports PKI and is
       configured with a Certificate and Private Key, the coap-client does not need to have a
       Pre-Shared Key (-k) or Certificate (-c) configured.

       The URI’s host part may be a DNS name or a literal IP address. Note that, for IPv6 address
       references, angle brackets are required (c.f. EXAMPLES).


       -a addr
           The local address of the interface that has to be used.

       -b [num,]size
           The block size to be used in GET/PUT/POST requests (value must be a multiple of 16 not
           larger than 1024 as libcoap uses a fixed maximum PDU size of 1400 bytes). If num is
           present, the request chain will start at block num. When the server includes a Block2
           option in its response to a GET request, coap-client will automatically retrieve the
           subsequent block from the server until there are no more outstanding blocks for the
           requested content.

       -e text
           Include text as payload (use percent-encoding for non-ASCII characters).

       -f file
           File to send with PUT/POST (use - for STDIN).

       -l list
           Fail to send some datagrams specified by a comma separated list of numbers or number
           ranges (debugging only).

       -l loss%
           Randomly failed to send datagams with the specified probability - 100% all datagrams,
           0% no datagrams (debugging only).

       -m method
           The request method for action (get|put|post|delete), default is get. (Note that the
           string passed to -m is compared case-insensitive.)

       -o file
           A filename to store data retrieved with GET.

       -p port
           The port to listen on.

           Use reliable protocol (TCP or TLS).

       -s duration
           Subscribe to / observe the resource specified by URI for the given duration in

       -t type
           Content format for given resource for PUT/POST.  type must be either a numeric value
           reflecting a valid CoAP content format or a string describing a registered format. The
           following registered content format descriptors are supported, with alternative
           shortcuts given in parentheses:

               text/plain (plain)
               application/link-format (link, link-format)
               application/xml (xml)
               application/octet-stream (binary, octet-stream)
               application/exi (exi)
               application/json (json)
               application/cbor (cbor)

       -v num
           The verbosity level to use (default 3, maximum is 9). Above 7, there is increased
           verbosity in GnuTLS and OpenSSL logging.

       -A type
           Accepted media type.  type must be either a numeric value reflecting a valid CoAP
           content format or a string that specifies a registered format as described for option

       -B seconds
           Break operation after waiting given seconds (default is 90).

       -K interval
           Send a ping after interval seconds of inactivity. If not specified (or 0), keep-alive
           is disabled (default).

           Send NON-confirmable message. If option -N is not specified, a confirmable message
           will be sent.

       -O num,text
           Add option num with contents of text to the request. If the text begins with 0x, then
           the hex text is converted to binary data.

       -P addr[:port]
           Address (and port) for proxy to use (automatically adds Proxy-Uri option to request).

       -T token
           Include the token to the request.

           Never include Uri-Host or Uri-Port options.


       (If supported by underlying (D)TLS library)

       -k key
           Pre-shared key for the specified user (-u option also required).

       -u user
           User identity for pre-shared key mode (-k option also required).


       (If supported by underlying (D)TLS library)

       -c certfile
           Use the specified PEM file which contains the CERTIFICATE and PRIVATE KEY information.

       -C cafile
           PEM file containing the CA Certificate that was used to sign the certfile defined
           using -c certfile. This will trigger the validation of the server certificate. If
           certfile is self-signed (as defined by -c certfile), then you need to have on the
           command line the same filename for both the certfile and cafile (as in -c certfile -C
           certfile) to trigger validation.

       -R root_cafile
           PEM file containing the set of trusted root CAs that are to be used to validate the
           server certificate. The -C cafile does not have to be in this list and is "trusted"
           for the verification. Alternatively, this can point to a directory containing a set of
           CA PEM files.


       •   Example

           coap-client coap://

       Query the resource / from server (using the GET method).

       •   Example

           coap-client -m get coap://[::1]/

       Query the resource / on localhost using the GET method to get back the summary defined

       •   Example

           coap-client -m get coap://[::1]/.well-known/core

       Query on the resource .well-known/core on localhost to get back a list of the known
       resources along with their attribute definitions.

       •   Example

           echo -n "mode=on" | coap-client -m put \

           coap://[2001:db8:c001:f00d:221:2eff:ff00:2704]:5683/actuators/leds?color=r -f-
       Send text mode=on to resource actuators/leds?color=r on the endpoint with address
       2001:db8:c001:f00d:221:2eff:ff00:2704 and port 5683. Note that the port 5683 is the
       default port and isn’t actually required in this instance.

       •   Example

           coap-client -m put coap://[fec0::3]/ck -T 3a -t binary -f to_upload

       Put the contents of file to_upload with content type binary (i.e.
       application/octet-stream) into resource ck on fec0::3 using a token of 3a via the PUT


       There are no configuration files.



           Failure (syntax or usage error; configuration error; document processing failure;
           unexpected error)


       Please report bugs on the mailing list for libcoap:


       The libcoap project <>