noble (3) upsclient.3.gz

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)