erl_call

19962016 Ericsson AB. All Rights Reserved. Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0 Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License. erl_call Torbjörn Törnkvist Torbjörn Törnkvist Bjarne Däcker Torbjörn Törnkvist 1997-05-16 B erl_call.xml

erl_call Call/start a distributed Erlang node.

makes it possible to start and/or communicate with a distributed Erlang node. It is built upon the library as an example application. Its purpose is to use a Unix shell script to interact with a distributed Erlang node. It performs all communication with the Erlang rex server, using the standard Erlang RPC facility. It does not require any special software to be run at the Erlang target node.

The main use is to either start a distributed Erlang node or to make an ordinary function call. However, it is also possible to pipe an Erlang module to and have it compiled, or to pipe a sequence of Erlang expressions to be evaluated (similar to the Erlang shell).

Options, which cause to be read, can be used with advantage, as scripts from within (Unix) shell scripts. Another nice use of could be from (HTTP) CGI-bin scripts.

erl_call <options> Start/call Erlang.

Starts/calls Erlang.

Each option flag is described below with its name, type, and meaning.

-a [Mod [Fun [Args]]]]

(Optional.) Applies the specified function and returns the result. must be specified. However, start and [] are assumed for unspecified and , respectively. is to be in the same format as for erlang:apply/3 in ERTS.

Notice that this flag takes exactly one argument, so quoting can be necessary to group , , and in a manner dependent on the behavior of your command shell.

-c Cookie

(Optional.) Use this option to specify a certain cookie. If no cookie is specified, the file is read and its content is used as cookie. The Erlang node we want to communicate with must have the same cookie.

-d

(Optional.) Debug mode. This causes all I/O to be output to the file, where is the node name of the Erlang node in question.

-e

(Optional.) Reads a sequence of Erlang expressions, separated by comma (,) and ended with a full stop (.), from until EOF (Control-D). Evaluates the expressions and returns the result from the last expression. Returns on success.

-h HiddenName

(Optional.) Specifies the name of the hidden node that represents.

-m

(Optional.) Reads an Erlang module from and compiles it.

-n Node

(One of is required.) Has the same meaning as and can still be used for backward compatibility reasons.

-name Node

(One of is required.) is the name of the node to be started or communicated with. It is assumed that is started with , which means that fully qualified long node names are used. If option is specified, an Erlang node will (if necessary) be started with .

-q

(Optional.) Halts the Erlang node specified with switch -n. This switch overrides switch -s.

-r

(Optional.) Generates a random name of the hidden node that represents.

-s

(Optional.) Starts a distributed Erlang node if necessary. This means that in a sequence of calls, where '' and '' are constant, only the first call starts the Erlang node. This makes the rest of the communication very fast. This flag is currently only available on Unix-like platforms (Linux, Mac OS X, Solaris, and so on).

-sname Node

(One of is required.) is the name of the node to be started or communicated with. It is assumed that is started with , which means that short node names are used. If option is specified, an Erlang node is started (if necessary) with .

-v

(Optional.) Prints a lot of information. This is only useful for the developer and maintainer of .

-x ErlScript

(Optional.) Specifies another name of the Erlang startup script to be used. If not specified, the standard startup script is used.

Examples

To start an Erlang node and call :

To terminate an Erlang node by calling :

To apply with many arguments:

To evaluate some expressions (the input ends with EOF (Control-D)):

To compile a module and run it (again, the input ends with EOF (Control-D)):

(In the example, the output has been formatted afterwards.)


        P = processes(),
        F = fun(X) -> {X,process_info(X,registered_name)} end,
        lists:map(F,[],P).
^D
[{,
                  {registered_name,init}},
 {,
                  {registered_name,erl_prim_loader}},
 {,
                  {registered_name,error_logger}},
 {,
                  {registered_name,application_controller}},
 {,
                  {registered_name,kernel}},
 {,
                  []},
 {,
                  {registered_name,kernel_sup}},
 {,
                  {registered_name,net_sup}},
 {,
                  {registered_name,net_kernel}},
 {,
                  []},
 {,
                  {registered_name,global_name_server}},
 {,
                  {registered_name,auth}},
 {,
                  {registered_name,rex}},
 {,
                  []},
 {,
                  {registered_name,file_server}},
 {,
                  {registered_name,code_server}},
 {,
                  {registered_name,user}},
 {,
                  []}]
    ]]>