net_adm (kernel v10.6.1)

Various Erlang net administration routines.

This module contains various network utility functions.

Files

File .hosts.erlang consists of a number of host names written as Erlang terms. It is looked for in the current work directory, the user's home directory, and $OTPROOT (the root directory of Erlang/OTP), in that order.

The format of file .hosts.erlang must be one host name per line. The host names must be within quotes.

Example:

'super.eua.ericsson.se'.
'renat.eua.ericsson.se'.
'grouse.eua.ericsson.se'.
'gauffin1.eua.ericsson.se'.
^ (new line)

Summary

Types

verbosity()

Functions

dns_hostname(Host)

Returns the official name of Host, or {error, Host} if no such name is found. See also inet.

host_file()

Reads file .hosts.erlang, see section Files. Returns the hosts in this file as a list. Returns {error, Reason} if the file cannot be read or the Erlang terms on the file cannot be interpreted.

localhost()

Returns the name of the local host. If Erlang was started with command-line flag -name, Name is the fully qualified name.

names()

names(Host)

Returns the names and associated port numbers of the Erlang nodes that epmd registered at the specified host.

ping(Node)

Sets up a connection to Node. Returns pong if it is successful, otherwise pang.

world()

world(Arg)

Calls names(Host) for all hosts that are specified in the Erlang host file .hosts.erlang, collects the replies, and then evaluates ping(Node) on all those nodes. Returns the list of all nodes that are successfully pinged.

world_list(Hosts)

world_list(Hosts, Arg)

Same as world/0,1, but the hosts are specified as argument instead of being read from .hosts.erlang.

Types

verbosity()

(not exported)

-type verbosity() :: silent | verbose.

Functions

dns_hostname(Host :: atom() | string()) -> Result

Types

Result = {ok, Name} | {error, Host}

Name = string()

Returns the official name of Host, or {error, Host} if no such name is found. See also inet.

host_file() -> Result

Types

Result = Hosts | {error, Reason}

Reason = file:posix() |
          badarg | terminated | system_limit |
          {Line :: integer(), Mod :: module(), Term :: term()}

Hosts = [Host :: atom()]

Reads file .hosts.erlang, see section Files. Returns the hosts in this file as a list. Returns {error, Reason} if the file cannot be read or the Erlang terms on the file cannot be interpreted.

localhost() -> Name

Types

Name = string()

Returns the name of the local host. If Erlang was started with command-line flag -name, Name is the fully qualified name.

names() ≡ names(net_adm:localhost())

names(Host) -> Result

Types

Host = atom() | string() | inet:ip_address()

Result = {ok, [{Name, Port}]} | {error, Reason}

Port = non_neg_integer()

Reason = address | file:posix()

Name = string()

Returns the names and associated port numbers of the Erlang nodes that epmd registered at the specified host.

Similar to epmd -names, see erts:epmd.

Returns {error, address} if epmd is not operational.

Example:

(arne@dunn)1> net_adm:names().
{ok,[{"arne",40262}]}

ping(Node :: atom()) -> pong | pang

Sets up a connection to Node. Returns pong if it is successful, otherwise pang.

world() ≡ world(silent)

world(Arg :: verbosity()) -> [node()]

If Arg == verbose, the function writes information about which nodes it is pinging to stdout.

This function can be useful when a node is started, and the names of the other network nodes are not initially known.

Returns {error, Reason} if host_file/0 returns {error, Reason}.

world_list(Hosts) ≡ world_list(Hosts, silent)

world_list(Hosts :: [atom()], Arg :: verbosity()) -> [node()]

Same as world/0,1, but the hosts are specified as argument instead of being read from .hosts.erlang.