---
name: "ct_slave"
section: "3erl"
platform: "linux"
package: "erlang-manpages"
version: "1:25.2.3+dfsg-1+deb12u4"
release: "Debian 12 (Bookworm)"
platforms: ["linux"]
url: "https://new.carta.tech/ct_slave"
---

# ct\_slave(3erl)

Common Test framework functions for starting and stopping nodes for Large-Scale Testing.

## NAME

ct\_slave - Common Test framework functions for starting and stopping\
     nodes for Large-Scale Testing.

## DESCRIPTION

*Common Test* framework functions for starting and stopping nodes for Large-Scale Testing.

This module exports functions used by the *Common Test* Master to start and stop "slave" nodes. It is the default callback module for the *{init, node\_start}* term in the Test Specification.

## EXPORTS

**start(Node) -\> Result**\

Types:

Node = atom()\
 Result = {ok, NodeName} \| {error, Reason, NodeName}\
 Reason = already\_started \| started\_not\_connected \| boot\_timeout \| init\_timeout \| startup\_timeout \| not\_alive\
 NodeName = atom()\

Starts an Erlang node with name *Node* on the local host.

See also *ct\_slave:start/3*.

**start(HostOrNode, NodeOrOpts) -\> Result**\

Types:

HostOrNode = atom()\
 NodeOrOpts = atom() \| list()\
 Result = {ok, NodeName} \| {error, Reason, NodeName}\
 Reason = already\_started \| started\_not\_connected \| boot\_timeout \| init\_timeout \| startup\_timeout \| not\_alive\
 NodeName = atom()\

Starts an Erlang node with default options on a specified host, or on the local host with specified options. That is, the call is interpreted as *start(Host, Node)* when the second argument is atom-valued and *start(Node, Opts)* when it is list-valued.

See also *ct\_slave:start/3*.

**start(Host, Node, Opts) -\> Result**\

Types:

Node = atom()\
 Host = atom()\
 Opts = \[OptTuples\]\
 OptTuples = {username, Username} \| {password, Password} \| {boot\_timeout, BootTimeout} \| {init\_timeout, InitTimeout} \| {startup\_timeout, StartupTimeout} \| {startup\_functions, StartupFunctions} \| {monitor\_master, Monitor} \| {kill\_if\_fail, KillIfFail} \| {erl\_flags, ErlangFlags} \| {env, \[{EnvVar, Value}\]}\
 Username = string()\
 Password = string()\
 BootTimeout = integer()\
 InitTimeout = integer()\
 StartupTimeout = integer()\
 StartupFunctions = \[StartupFunctionSpec\]\
 StartupFunctionSpec = {Module, Function, Arguments}\
 Module = atom()\
 Function = atom()\
 Arguments = \[term\]\
 Monitor = bool()\
 KillIfFail = bool()\
 ErlangFlags = string()\
 EnvVar = string()\
 Value = string()\
 Result = {ok, NodeName} \| {error, Reason, NodeName}\
 Reason = already\_started \| started\_not\_connected \| boot\_timeout \| init\_timeout \| startup\_timeout \| not\_alive\
 NodeName = atom()\

Starts an Erlang node with name *Node* on host *Host* as specified by the combination of options in *Opts*.

Options *Username* and *Password* are used to log on to the remote host *Host*. *Username*, if omitted, defaults to the current username. *Password* is empty by default.

A list of functions specified in option *Startup* are executed after startup of the node. Notice that all used modules are to be present in the code path on *Host*.

The time-outs are applied as follows:

- ***BootTimeout*:**

  The time to start the Erlang node, in seconds. Defaults to 3 seconds. If the node is not pingable within this time, the result *{error, boot\_timeout, NodeName}* is returned.

- ***InitTimeout*:**

  The time to wait for the node until it calls the internal callback function informing master about a successful startup. Defaults to 1 second. In case of a timed out message, the result *{error, init\_timeout, NodeName}* is returned.

- ***StartupTimeout*:**

  The time to wait until the node stops to run *StartupFunctions*. Defaults to 1 second. If this time-out occurs, the result *{error, startup\_timeout, NodeName}* is returned.

*Options:*

- ***monitor\_master*:**

  Specifies if the slave node is to be stopped if the master node stops. Defaults to *false*.

- ***kill\_if\_fail*:**

  Specifies if the slave node is to be killed if a time-out occurs during initialization or startup. Defaults to *true*. Notice that the node can also be still alive it the boot time-out occurred, but it is not killed in this case.

- ***erl\_flags*:**

  Specifies which flags are added to the parameters of the executable *erl*.

- ***env*:**

  Specifies a list of environment variables that will extend the environment.

*Special return values:*

- \*

  *{error, already\_started, NodeName}* if the node with the specified name is already started on a specified host.

- \*

  *{error, started\_not\_connected, NodeName}* if the node is started, but not connected to the master node.

- \*

  *{error, not\_alive, NodeName}* if the node on which *ct\_slave:start/3* is called, is not alive. Notice that *NodeName* is the name of the current node in this case.

**stop(Node) -\> Result**\

Types:

Node = atom()\
 Result = {ok, NodeName} \| {error, Reason, NodeName}\
 Reason = not\_started \| not\_connected \| stop\_timeout\

Stops the running Erlang node with name *Node* on the local host.

**stop(Host, Node) -\> Result**\

Types:

Host = atom()\
 Node = atom()\
 Result = {ok, NodeName} \| {error, Reason, NodeName}\
 Reason = not\_started \| not\_connected \| stop\_timeout\
 NodeName = atom()\

Stops the running Erlang node with name *Node* on host *Host*.