erl_call - Call/start a distributed Erlang node.
Please see following description for synopsis
erl_call(1) User Commands erl_call(1)
NAME
erl_call - Call/start a distributed Erlang node.
DESCRIPTION
erl_call makes it possible to start and/or communicate with a distrib-
uted Erlang node. It is built upon the Erl_Interface 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 erl_call and have it compiled, or to pipe a sequence of
Erlang expressions to be evaluated (similar to the Erlang shell).
Options, which cause stdin to be read, can be used with advantage, as
scripts from within (Unix) shell scripts. Another nice use of erl_call
could be from (HTTP) CGI-bin scripts.
EXPORTS
erl_call <options>
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. Mod must be specified. However, start and [] are
assumed for unspecified Fun and Args, respectively. Args 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 Mod, Fun, and Args 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 ~/.erlang.cookie 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 ~/.erl_call.out.Nodename file, where Nodename is the
node name of the Erlang node in question.
-e:
(Optional.) Reads a sequence of Erlang expressions, sepa-
rated by comma (,) and ended with a full stop (.), from
stdin until EOF (Control-D). Evaluates the expressions and
returns the result from the last expression. Returns
{ok,Result} on success.
-h HiddenName:
(Optional.) Specifies the name of the hidden node that
erl_call represents.
-m:
(Optional.) Reads an Erlang module from stdin and compiles
it.
-n Node:
(One of -n, -name, -sname is required.) Has the same meaning
as -name and can still be used for backward compatibility
reasons.
-name Node:
(One of -n, -name, -sname is required.) Node is the name of
the node to be started or communicated with. It is assumed
that Node is started with erl -name, which means that fully
qualified long node names are used. If option -s is speci-
fied, an Erlang node will (if necessary) be started with erl
-name.
-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
erl_call represents.
-s:
(Optional.) Starts a distributed Erlang node if necessary.
This means that in a sequence of calls, where '-s' and '-n
Node' 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 -n, -name, -sname is required.) Node is the name of
the node to be started or communicated with. It is assumed
that Node is started with erl -sname, which means that short
node names are used. If option -s is specified, an Erlang
node is started (if necessary) with erl -sname.
-v:
(Optional.) Prints a lot of verbose information. This is
only useful for the developer and maintainer of erl_call.
-x ErlScript:
(Optional.) Specifies another name of the Erlang startup
script to be used. If not specified, the standard erl
startup script is used.
EXAMPLES
To start an Erlang node and call erlang:time/0:
erl_call -s -a 'erlang time' -n madonna
{18,27,34}
To terminate an Erlang node by calling erlang:halt/0:
erl_call -s -a 'erlang halt' -n madonna
To apply with many arguments:
erl_call -s -a 'lists seq [1,10]' -n madonna
To evaluate some expressions (the input ends with EOF (Control-D)):
erl_call -s -e -n madonna
statistics(runtime),
X=1,
Y=2,
{_,T}=statistics(runtime),
{X+Y,T}.
^D
{ok,{3,0}}
To compile a module and run it (again, the input ends with EOF (Con-
trol-D)):
(In the example, the output has been formatted afterwards.)
erl_call -s -m -a procnames -n madonna
-module(procnames).
-compile(export_all).
start() ->
P = processes(),
F = fun(X) -> {X,process_info(X,registered_name)} end,
lists:map(F,[],P).
^D
[{<madonna@chivas.du.etx.ericsson.se,0,0>,
{registered_name,init}},
{<madonna@chivas.du.etx.ericsson.se,2,0>,
{registered_name,erl_prim_loader}},
{<madonna@chivas.du.etx.ericsson.se,4,0>,
{registered_name,error_logger}},
{<madonna@chivas.du.etx.ericsson.se,5,0>,
{registered_name,application_controller}},
{<madonna@chivas.du.etx.ericsson.se,6,0>,
{registered_name,kernel}},
{<madonna@chivas.du.etx.ericsson.se,7,0>,
[]},
{<madonna@chivas.du.etx.ericsson.se,8,0>,
{registered_name,kernel_sup}},
{<madonna@chivas.du.etx.ericsson.se,9,0>,
{registered_name,net_sup}},
{<madonna@chivas.du.etx.ericsson.se,10,0>,
{registered_name,net_kernel}},
{<madonna@chivas.du.etx.ericsson.se,11,0>,
[]},
{<madonna@chivas.du.etx.ericsson.se,12,0>,
{registered_name,global_name_server}},
{<madonna@chivas.du.etx.ericsson.se,13,0>,
{registered_name,auth}},
{<madonna@chivas.du.etx.ericsson.se,14,0>,
{registered_name,rex}},
{<madonna@chivas.du.etx.ericsson.se,15,0>,
[]},
{<madonna@chivas.du.etx.ericsson.se,16,0>,
{registered_name,file_server}},
{<madonna@chivas.du.etx.ericsson.se,17,0>,
{registered_name,code_server}},
{<madonna@chivas.du.etx.ericsson.se,20,0>,
{registered_name,user}},
{<madonna@chivas.du.etx.ericsson.se,38,0>,
[]}]
Ericsson AB erl_interface 3.9.3 erl_call(1)