Difference between revisions of "OS (API)"

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(Another synonym)
(add cancelTimer and cancelAlarm calls.)
 
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The Operating System API allows for interfacing with the Lua based Operating System itself.
 
The Operating System API allows for interfacing with the Lua based Operating System itself.
  
<table style="width: 100%; border: solid 1px black; margin: 2px; border-spacing: 0px;">
 
<tr><td colspan="2" style="font-weight: bold; font-size: large; padding-bottom: .3em; border-bottom: solid #C9C9C9 1px; background: #D3FFC2; line-height:28px;">
 
[[File:Grid_disk.png|24px]]&nbsp;&nbsp;
 
OS (API)
 
</td></tr>
 
  
<tr><td style="width: 350px; background: #E0E0E0; padding: .4em; font-weight:bold;">Method Name</td><td style="background: #E0E0E0; padding: .4em; font-weight:bold;">Description</td></tr>
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{{API table|OS|image=Grid disk.png|2=
  
<tr style="background-color: #FFFFFF;"><td style="border-top: solid #C9C9C9 1px; padding: .4em;">[[os.version]]()</td>
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{{API table/row
<td style="border-top: solid #C9C9C9 1px; padding: .4em;">Returns the version of the OS the computer is running.</td></tr>
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|[[os.version]]()|{{type|string}} version
 +
|Returns the version of the OS the computer is running, which (for CraftOS) also contains the version of ComputerCraft.
 +
|odd}}
  
<tr style="background-color: #E8E8E8;"><td style="border-top: solid #C9C9C9 1px; padding: .4em;">[[os.getComputerID]]()</td>
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{{API table/row
<td style="border-top: solid #C9C9C9 1px; padding: .4em;">Returns the unique ID of this computer. [[os.computerID]]() also behaves exactly the same as [[os.getComputerID]]().</td></tr>
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|[[os.getComputerID]]()|{{type|number}} id
 +
|Returns the unique ID of this computer. [[os.computerID]]() also behaves exactly the same as [[os.getComputerID]]().
 +
|}}
  
<tr style="background-color: #FFFFFF;"><td style="border-top: solid #C9C9C9 1px; padding: .4em;">[[os.getComputerLabel]]()</td>
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{{API table/row
<td style="border-top: solid #C9C9C9 1px; padding: .4em;">Returns the label of this computer. [[os.computerLabel]]() also behaves exactly the same as [[os.getComputerLabel]]().</td></tr>
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|[[os.getComputerLabel]]()|{{type|string}}/{{type|nil}} label
 +
|Returns the label of this computer. [[os.computerLabel]]() also behaves exactly the same as [[os.getComputerLabel]]().
 +
|odd}}
  
<tr style="background-color: #E8E8E8;"><td style="border-top: solid #C9C9C9 1px; padding: .4em;">[[os.setComputerLabel]]( label )</td>
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{{API table/row
<td style="border-top: solid #C9C9C9 1px; padding: .4em;">Set the label of this computer.</td></tr>
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|[[os.setComputerLabel]]({{type|string}}/{{type|nil}} label)|{{type|nil}}
 +
|Set the label of this computer.
 +
|}}
  
<tr style="background-color: #FFFFFF;"><td style="border-top: solid #C9C9C9 1px; padding: .4em;">[[os.run]]( environment, programpath, arguments )</td>
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{{API table/row
<td style="border-top: solid #C9C9C9 1px; padding: .4em;">An advanced way of starting programs. A started program will have a given <var>environment</var> table which determines what functions it has available, as well as any variables it will be able to access by default. You may prefer to use the [[Shell (API)]] unless you need to do something special.</td></tr>
+
|[[os.run]]({{type|table}} environment, {{type|string}} programPath [, {{type|string}} arguments])
 +
|{{type|boolean}} success
 +
|An advanced way of starting programs. A started program will have a given <var>environment</var> table which determines what functions it has available, as well as any variables it will be able to access by default. You may prefer to use the [[Shell (API)]] unless you need to do something special.
 +
|odd}}
  
<tr style="background-color: #E8E8E8;"><td style="border-top: solid #C9C9C9 1px; padding: .4em;">[[#API|os.loadAPI]]( name )</td>
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{{API table/row
<td style="border-top: solid #C9C9C9 1px; padding: .4em;">Loads a Lua script as an API in it's own namespace (see example). It will be available to '''all''' programs that run on the terminal.</td></tr>
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|[[os.loadAPI]]({{type|string}} path)
 +
|{{type|boolean}} success
 +
|Loads a Lua script as an API in its own namespace. It will be available to '''all''' programs that run on the terminal.}}
  
<tr style="background-color: #FFFFFF;"><td style="border-top: solid #C9C9C9 1px; padding: .4em;">[[#API|os.unloadAPI]]( name )</td>
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{{API table/row
<td style="border-top: solid #C9C9C9 1px; padding: .4em;">Unloads a previously loaded API.</td></tr>
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|[[os.unloadAPI]]({{type|string}} name)|{{type|nil}}
 +
|Unloads a previously loaded API.
 +
|odd}}
  
<tr style="background-color: #E8E8E8;"><td style="border-top: solid #C9C9C9 1px; padding: .4em;">[[Os.pullEvent|os.pullEvent]]( target-event )</td>
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{{API table/row
<td style="border-top: solid #C9C9C9 1px; padding: .4em;">Blocks until the computer receives an event, or if <var>target-event</var> is specified, will block until an instance of <var>target-event</var> occurs. [[Os.pullEvent|os.pullEvent]]( target-event ) returns the event and any parameters the event may have. If a <var>target-event</var> is specified, the computer will not break for any other events (except termination).</td></tr>
+
|[[os.pullEvent]]([<nowiki/>{{type|string}} target-event])
 +
|{{type|string}} event, param1, param2, ...
 +
|Blocks until the computer receives an event, or if <var>target-event</var> is specified, will block until an instance of <var>target-event</var> occurs. [[os.pullEvent]](target-event) returns the event and any parameters the event may have. If a <var>target-event</var> is specified, the computer will not break for any other events (except termination).
 +
|}}
  
<tr style="background-color: #FFFFFF;"><td style="border-top: solid #C9C9C9 1px; padding: .4em;">[[#pullEvent|os.pullEventRaw]]()</td>
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{{API table/row
<td style="border-top: solid #C9C9C9 1px; padding: .4em;">Advanced version of pullEvent(). [[#pullEvent|os.pullEventRaw]]() will block until an event occurs, and then returns the event (any any parameters the event may have). Unlike [[Os.pullEvent|os.pullEvent]]( target-event ), this function will not break for system events, and can be used to handle termination events.</td></tr>
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|[[os.pullEventRaw]]([<nowiki/>{{type|string}} target-event])
 +
|{{type|string}} event, param1, param2, ...
 +
|Advanced version of pullEvent(). Blocks until the computer receives an event, or if <var>target-event</var> is specified, will block until an instance of <var>target-event</var> occurs. [[os.pullEventRaw]](target-event) returns the event and any parameters the event may have. Unlike [[os.pullEvent]](target-event), this function will not raise an error if a [[terminate_(event)|'terminate' event]] is received.
 +
|odd}}
  
<tr style="background-color: #E8E8E8;"><td style="border-top: solid #C9C9C9 1px; padding: .4em;">[[os.queueEvent]]( event, param1, param2, ... )</td>
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{{API table/row
<td style="border-top: solid #C9C9C9 1px; padding: .4em;">Adds an event to the event queue with the name <var>event</var> and the given parameters</td></tr>
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|[[os.queueEvent]]({{type|string}} event, param1, param2, ...)|{{type|nil}}
 +
|Adds an event to the event queue with the name <var>event</var> and the given parameters.
 +
|}}
  
<tr style="background-color: #FFFFFF;"><td style="border-top: solid #C9C9C9 1px; padding: .4em;">[[os.clock]]()</td>
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{{API table/row
<td style="border-top: solid #C9C9C9 1px; padding: .4em;">Returns CPU time.</td></tr>
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|[[os.clock]]()|{{type|number}} time
 +
|Returns the amount of time since the in-game computer was started.
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|odd}}
  
<tr style="background-color: #E8E8E8;"><td style="border-top: solid #C9C9C9 1px; padding: .4em;">[[os.startTimer]]( timeout )</td>
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{{API table/row
<td style="border-top: solid #C9C9C9 1px; padding: .4em;">Queues an event to be triggered after a number of seconds (<var>timeout</var>). The ID of the timer is returned from this function to differentiate multiple timers. Timers are one-shot; once they have fired an event you will need to start another one if you need a recurring timer.</td></tr>
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|[[os.startTimer]]({{Type|number}} timeout)|{{type|number}} timerID
 +
|Queues an event to be triggered after a number of seconds (<var>timeout</var>). The ID of the timer is returned from this function to differentiate multiple timers. Timers are one-shot; once they have fired an event you will need to start another one if you need a recurring timer.
 +
|}}
  
<tr style="background-color: #FFFFFF;"><td style="border-top: solid #C9C9C9 1px; padding: .4em;">[[os.sleep]]( timeout )</td>
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{{API table/row
<td style="border-top: solid #C9C9C9 1px; padding: .4em;">Makes the system wait a number of seconds before continuing in the program. [[os.sleep]]( timeout ) may also be used as simply "sleep( timeout )".</td></tr>
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|[[os.cancelTimer]]({{Type|number}} timerID)|{{type|nil}}
 +
|Cancels a running timer, to prevent it throwing an event.
 +
|}}
  
<tr style="background-color: #E8E8E8;"><td style="border-top: solid #C9C9C9 1px; padding: .4em;">[[os.time]]()</td>
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{{API table/row
<td style="border-top: solid #C9C9C9 1px; padding: .4em;">Returns the current Minecraft world time.</td></tr>
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|[[os.time]]()|{{type|number}} time
 +
|Returns the current in-game time.
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|odd}}
  
<tr style="background-color: #FFFFFF;"><td style="border-top: solid #C9C9C9 1px; padding: .4em;">[[os.day]]()</td>
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{{API table/row
<td style="border-top: solid #C9C9C9 1px; padding: .4em;">Returns the current Minecraft day.</td></tr>
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|[[os.sleep]]({{Type|number}} time)|{{type|nil}}
 +
|Makes the system wait a number of seconds before continuing in the program. [[os.sleep]](time) may also be used as simply "sleep(time)".
 +
|}}
  
<tr style="background-color: #E8E8E8;"><td style="border-top: solid #C9C9C9 1px; padding: .4em;">[[os.setAlarm]]( time )</td>
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{{API table/row
<td style="border-top: solid #C9C9C9 1px; padding: .4em;">Queues an event to be triggered at the specified Minecraft world <var>time</var>.</td></tr>
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|[[os.day]]()|{{type|number}} day
 +
|Return the current in-game day (the number of in-game days since the world was created).
 +
|odd}}
  
<tr style="background-color: #FFFFFF;"><td style="border-top: solid #C9C9C9 1px; padding: .4em;">[[os.shutdown]]()</td>
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{{API table/row
<td style="border-top: solid #C9C9C9 1px; padding: .4em;">Turns off the computer.</td></tr>
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|[[os.setAlarm]]({{type|number}} time)|{{type|number}} alarmID
 +
|Queues an event to be triggered at the specified in-game <var>time</var>.
 +
|}}
  
<tr style="background-color: #E8E8E8;"><td style="border-top: solid #C9C9C9 1px; padding: .4em;">[[os.reboot]]()</td>
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{{API table/row
<td style="border-top: solid #C9C9C9 1px; padding: .4em;">Reboots the computer.</td></tr>
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|[[os.cancelAlarm]]({{Type|number}} alarmID)|{{type|nil}}
</table>
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|Cancels a pending alarm, to prevent it throwing an event.
 +
|}}
 +
 
 +
{{API table/row
 +
|[[os.shutdown]]()|{{type|nil}}
 +
|Turns off the computer.
 +
|odd}}
 +
 
 +
{{API table/row
 +
|[[os.reboot]]()|{{type|nil}}
 +
|Reboots the computer.
 +
|}}
 +
 
 +
}}
  
  
 
[[Category:APIs]]
 
[[Category:APIs]]
  
== API ==
+
== APIs ==
  
API are programs which are loaded in to the OS itself, and expose functions which other programs may use. The stock [[:Category:APIs|APIs]] that ship with ComputerCraft are loaded in this way, and may be replaced by a computer's user or programs.
+
APIs are Lua files which are loaded into the OS itself, and expose functions which other programs may use. The stock [[:Category:APIs|APIs]] that ship with ComputerCraft are loaded in this way, and may be replaced by a computer’s user or programs.
  
The following is an example of a valid implementation of an API, and, it's usage after being registered:
+
The following is an example of a valid implementation of an API, and its usage after being registered:
 
<code>
 
<code>
 
   -- "apiTest" file
 
   -- "apiTest" file

Latest revision as of 06:54, 4 January 2015

The Operating System API allows for interfacing with the Lua based Operating System itself.


Grid disk.png  OS (API)
Function Return values Description
os.version() string version Returns the version of the OS the computer is running, which (for CraftOS) also contains the version of ComputerCraft.
os.getComputerID() number id Returns the unique ID of this computer. os.computerID() also behaves exactly the same as os.getComputerID().
os.getComputerLabel() string/nil label Returns the label of this computer. os.computerLabel() also behaves exactly the same as os.getComputerLabel().
os.setComputerLabel(string/nil label) nil Set the label of this computer.
os.run(table environment, string programPath [, string arguments]) boolean success An advanced way of starting programs. A started program will have a given environment table which determines what functions it has available, as well as any variables it will be able to access by default. You may prefer to use the Shell (API) unless you need to do something special.
os.loadAPI(string path) boolean success Loads a Lua script as an API in its own namespace. It will be available to all programs that run on the terminal.
os.unloadAPI(string name) nil Unloads a previously loaded API.
os.pullEvent([string target-event]) string event, param1, param2, ... Blocks until the computer receives an event, or if target-event is specified, will block until an instance of target-event occurs. os.pullEvent(target-event) returns the event and any parameters the event may have. If a target-event is specified, the computer will not break for any other events (except termination).
os.pullEventRaw([string target-event]) string event, param1, param2, ... Advanced version of pullEvent(). Blocks until the computer receives an event, or if target-event is specified, will block until an instance of target-event occurs. os.pullEventRaw(target-event) returns the event and any parameters the event may have. Unlike os.pullEvent(target-event), this function will not raise an error if a 'terminate' event is received.
os.queueEvent(string event, param1, param2, ...) nil Adds an event to the event queue with the name event and the given parameters.
os.clock() number time Returns the amount of time since the in-game computer was started.
os.startTimer(number timeout) number timerID Queues an event to be triggered after a number of seconds (timeout). The ID of the timer is returned from this function to differentiate multiple timers. Timers are one-shot; once they have fired an event you will need to start another one if you need a recurring timer.
os.cancelTimer(number timerID) nil Cancels a running timer, to prevent it throwing an event.
os.time() number time Returns the current in-game time.
os.sleep(number time) nil Makes the system wait a number of seconds before continuing in the program. os.sleep(time) may also be used as simply "sleep(time)".
os.day() number day Return the current in-game day (the number of in-game days since the world was created).
os.setAlarm(number time) number alarmID Queues an event to be triggered at the specified in-game time.
os.cancelAlarm(number alarmID) nil Cancels a pending alarm, to prevent it throwing an event.
os.shutdown() nil Turns off the computer.
os.reboot() nil Reboots the computer.

APIs

APIs are Lua files which are loaded into the OS itself, and expose functions which other programs may use. The stock APIs that ship with ComputerCraft are loaded in this way, and may be replaced by a computer’s user or programs.

The following is an example of a valid implementation of an API, and its usage after being registered:

 -- "apiTest" file
 function foo(bar)
   print(bar)
 end
 
 -- "program" file
 os.loadAPI("apiTest")
 apiTest.foo("this is a test")

os.pullEvent()

os.pullEvent() causes the current program to pause, retrieving the next event from the computer's queue of events. If there is no event to read, then the program will stall until such an event becomes available. Note that if a program has not attempted to pull an event in the past ten seconds, it will be forcefully terminated to prevent CPU waste in SMP environments.

os.pullEvent() returns the name of the event that was read, as well as up to five parameters: local event, p1, p2, p3, p4, p5 = os.pullEvent()

os.pullEvent() is usually run inside a 'while true do' loop.

An advanced version of this method os.pullEventRaw bypasses the normal handling of events from the OS. You may use this to act on the "Terminate" event (triggered when holding Ctrl-T) for custom termination logic.