upsclient(3)

NAME

   upsclient - Network UPS Tools client access library

DESCRIPTION

   The Network UPS Tools (NUT) upsclient library provides a number of
   useful functions for programs to use when communicating with upsd(8).
   Many of the low-level socket and protocol details are handled
   automatically when using this interface.

   State is maintained across calls in an opaque structure called
   UPSCONN_t. Callers are expected to create one per connection. These
   will be provided to most of the upsclient functions. The format of this
   structure is subject to change, and client programs must not reference
   elements within it directly.

INITIALIZATION AND CLEANUP

   Before creating any connection, and in general using any upscli
   function, you must call upscli_init(3) with proper parameters to
   initialize upscli module.

   To register specific host security policy, you must call
   upscli_add_host_cert(3) before initialize connection to it.

   In the same way, just before exiting, and after all upscli usage, you
   must call upscli_cleanup(3) to flush cache files and perform other
   cleanup.

NETWORK FUNCTIONS

   To create a new connection, use upscli_connect(3). This will also
   initialize the UPSCONN_t structure. To verify that a connection has
   been established later, upscli_fd(3) can be used to return the file
   descriptor. Clients wishing to check for the presence and operation of
   SSL on a connection may call upscli_ssl(3).

   The majority of clients will use upscli_get(3) to retrieve single items
   from the server. To retrieve a list, use upscli_list_start(3) to get it
   started, then call upscli_list_next(3) for each element.

   Raw lines of text may be sent to upsd(8) with upscli_sendline(3).
   Reading raw lines is possible with upscli_readline(3). Client programs
   are expected to format these lines according to the protocol, as no
   checking will be performed before transmission.

   At the end of a connection, you must call upsclient_disconnect(3) to
   disconnect from upsd and release any dynamic memory associated with the
   UPSCONN_t structure. Failure to call this function will result in
   memory and file descriptor leaks in your program.

ERROR HANDLING

   In the event of an error, upscli_strerror(3) will provide
   human-readable details on what happened. upscli_upserror(3) may also be
   used to retrieve the error number. These numbers are defined in
   upsclient.h as UPSCLI_ERR_*.

SEE ALSO

   libupsclient-config(1), upscli_init(3), upscli_cleanup(3),
   upscli_add_host_cert(3), upscli_connect(3), upscli_disconnect(3),
   upscli_fd(3), upscli_getvar(3), upscli_list_next(3),
   upscli_list_start(3), upscli_readline(3), upscli_sendline(3),
   upscli_splitaddr(3), upscli_splitname(3), upscli_ssl(3),
   upscli_strerror(3), upscli_upserror(3)

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