docs/ubus.txt

   1 include::header.txt[]
   2
   3 == uBus - IPC/RPC
   4
   5 uBus is the interconnect system used by most service running on a _LEDE_ setup.
   6 Service can connect to the bus and provide methods that can be called by other services or clients.
   7
   8 There is a CLI that can be used to communicate with services on the bus.
   9
  10 ----
  11 root@lede:/# ubus
  12 Usage: ubus [<options>] <command> [arguments...]
  13 Options:
  14 -s <socket>:            Set the unix domain socket to connect to
  15 -t <timeout>:           Set the timeout (in seconds) for a command to complete
  16 -S:                     Use simplified output (for scripts)
  17 -v:                     More verbose output
  18
  19 Commands:
  20 - list [<path>]                 List objects
  21 - call <path> <method> [<message>]      Call an object method
  22 - listen [<path>...]                    Listen for events
  23 - send <type> [<message>]               Send an event
  24 - wait_for <object> [<object>...]       Wait for multiple objects to appear on ubus
  25 ----
  26
  27 To find out which services are currently running on the bus simply use the list command. This will show a complete list.
  28
  29 ----
  30 root@lede:/# ubus list
  31 dhcp
  32 log
  33 network
  34 network.device
  35 network.interface
  36 network.interface.loopback
  37 network.interface.wan
  38 network.interface.wan6
  39 network.wireless
  40 service
  41 system
  42 ----
  43
  44 To find out which methods a specific service provides also use the list command but add a few more parameters to see a complete list
  45
  46 ----
  47 root@OpenWrt:/# ubus -v list system
  48 'system' @6b093875
  49         "board":{}
  50         "info":{}
  51         "upgrade":{}
  52         "watchdog":{"frequency":"Integer","timeout":"Integer","stop":"Boolean"}
  53         "signal":{"pid":"Integer","signum":"Integer"}
  54 ----
  55
  56 You can now call a remote method and receive a reply. A reply may be a simple integer return code or a more complete reply. Internally the bus uses a blob format, the CLI conveniently converts this to JSON.
  57
  58 ----
  59 root@lede:/# ubus call system board
  60 {
  61         "kernel": "4.4.6",
  62         "hostname": "lede",
  63         "system": "MIPS Malta",
  64         "release": {
  65                 "distribution": "LEDE",
  66                 "version": "HEAD",
  67                 "revision": "3",
  68                 "codename": "designated_driver",
  69                 "target": "malta\/le",
  70                 "description": "LEDE Designated Driver 3"
  71         }
  72 }
  73 ----
  74
  75 You can call a method and pass it some parameters by simply appending a JSON structure to the CLI command.
  76 ----
  77 root@lede:/# ubus call system signal '{ "pid": 123, "signum": 9 }'
  78 root@lede:/# echo $?
  79 0
  80 ----
  81
  82