1erl_call(1)                      User Commands                     erl_call(1)
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NAME

6       erl_call - Call/start a distributed Erlang node.
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DESCRIPTION

9       erl_call  makes it possible to start and/or communicate with a distrib‐
10       uted Erlang node. It is built upon  the  Erl_Interface  library  as  an
11       example  application.  Its  purpose  is  to  use a Unix shell script to
12       interact with a distributed Erlang node. It performs all  communication
13       with  the Erlang rex server, using the standard Erlang RPC facility. It
14       does not require any special software to be run at  the  Erlang  target
15       node.
16
17       The main use is to either start a distributed Erlang node or to make an
18       ordinary function call. However, it is also possible to pipe an  Erlang
19       module  to  erl_call  and  have  it  compiled, or to pipe a sequence of
20       Erlang expressions to be evaluated (similar to the Erlang shell).
21
22       Options, which cause stdin to be read, can be used with  advantage,  as
23       scripts  from within (Unix) shell scripts. Another nice use of erl_call
24       could be from (HTTP) CGI-bin scripts.
25

EXPORTS

27       erl_call <options>
28
29              Starts/calls Erlang.
30
31              Each option flag is described below with  its  name,  type,  and
32              meaning.
33
34                -a [Mod [Fun [Args]]]]:
35                  (Optional.)  Applies  the specified function and returns the
36                  result. Mod must be specified. However,  start  and  []  are
37                  assumed  for unspecified Fun and Args, respectively. Args is
38                  to be in the same format as for erlang:apply/3 in ERTS.
39
40                  Notice that this flag takes exactly one argument, so quoting
41                  can  be  necessary  to  group Mod, Fun, and Args in a manner
42                  dependent on the behavior of your command shell.
43
44                -c Cookie:
45                  (Optional.) Use this option to specify a certain cookie.  If
46                  no  cookie  is  specified, the ~/.erlang.cookie file is read
47                  and its content is used as cookie. The Erlang node  we  want
48                  to communicate with must have the same cookie.
49
50                -d:
51                  (Optional.)  Debug mode. This causes all I/O to be output to
52                  the ~/.erl_call.out.Nodename file,  where  Nodename  is  the
53                  node name of the Erlang node in question.
54
55                -e:
56                  (Optional.)  Reads  a  sequence of Erlang expressions, sepa‐
57                  rated by comma (,) and ended with  a  full  stop  (.),  from
58                  stdin  until  EOF (Control-D). Evaluates the expressions and
59                  returns  the  result  from  the  last  expression.   Returns
60                  {ok,Result} on success.
61
62                -h HiddenName:
63                  (Optional.)  Specifies  the  name  of  the  hidden node that
64                  erl_call represents.
65
66                -m:
67                  (Optional.) Reads an Erlang module from stdin  and  compiles
68                  it.
69
70                -n Node:
71                  (One of -n, -name, -sname is required.) Has the same meaning
72                  as -name and can still be used  for  backward  compatibility
73                  reasons.
74
75                -name Node:
76                  (One  of -n, -name, -sname is required.) Node is the name of
77                  the node to be started or communicated with. It  is  assumed
78                  that  Node is started with erl -name, which means that fully
79                  qualified long node names are used. If option -s  is  speci‐
80                  fied, an Erlang node will (if necessary) be started with erl
81                  -name.
82
83                -q:
84                  (Optional.) Halts the Erlang node specified with switch  -n.
85                  This switch overrides switch -s.
86
87                -r:
88                  (Optional.)  Generates a random name of the hidden node that
89                  erl_call represents.
90
91                -s:
92                  (Optional.) Starts a distributed Erlang node  if  necessary.
93                  This  means  that in a sequence of calls, where '-s' and '-n
94                  Node' are constant, only the first call  starts  the  Erlang
95                  node.  This  makes  the rest of the communication very fast.
96                  This flag is currently only available on Unix-like platforms
97                  (Linux, Mac OS X, Solaris, and so on).
98
99                -sname Node:
100                  (One  of -n, -name, -sname is required.) Node is the name of
101                  the node to be started or communicated with. It  is  assumed
102                  that Node is started with erl -sname, which means that short
103                  node names are used. If option -s is  specified,  an  Erlang
104                  node is started (if necessary) with erl -sname.
105
106                -v:
107                  (Optional.)  Prints  a  lot  of verbose information. This is
108                  only useful for the developer and maintainer of erl_call.
109
110                -x ErlScript:
111                  (Optional.) Specifies another name  of  the  Erlang  startup
112                  script  to  be  used.  If  not  specified,  the standard erl
113                  startup script is used.
114

EXAMPLES

116       To start an Erlang node and call erlang:time/0:
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118       erl_call -s -a 'erlang time' -n madonna
119       {18,27,34}
120
121
122       To terminate an Erlang node by calling erlang:halt/0:
123
124       erl_call -s -a 'erlang halt' -n madonna
125
126
127       To apply with many arguments:
128
129       erl_call -s -a 'lists seq [1,10]' -n madonna
130
131
132       To evaluate some expressions (the input ends with EOF (Control-D)):
133
134       erl_call -s -e -n madonna
135       statistics(runtime),
136       X=1,
137       Y=2,
138       {_,T}=statistics(runtime),
139       {X+Y,T}.
140       ^D
141       {ok,{3,0}}
142
143
144       To compile a module and run it (again, the input ends  with  EOF  (Con‐
145       trol-D)):
146
147       (In the example, the output has been formatted afterwards.)
148
149       erl_call -s -m -a procnames -n madonna
150       -module(procnames).
151       -compile(export_all).
152       start() ->
153               P = processes(),
154               F = fun(X) -> {X,process_info(X,registered_name)} end,
155               lists:map(F,[],P).
156       ^D
157       [{<madonna@chivas.du.etx.ericsson.se,0,0>,
158                         {registered_name,init}},
159        {<madonna@chivas.du.etx.ericsson.se,2,0>,
160                         {registered_name,erl_prim_loader}},
161        {<madonna@chivas.du.etx.ericsson.se,4,0>,
162                         {registered_name,error_logger}},
163        {<madonna@chivas.du.etx.ericsson.se,5,0>,
164                         {registered_name,application_controller}},
165        {<madonna@chivas.du.etx.ericsson.se,6,0>,
166                         {registered_name,kernel}},
167        {<madonna@chivas.du.etx.ericsson.se,7,0>,
168                         []},
169        {<madonna@chivas.du.etx.ericsson.se,8,0>,
170                         {registered_name,kernel_sup}},
171        {<madonna@chivas.du.etx.ericsson.se,9,0>,
172                         {registered_name,net_sup}},
173        {<madonna@chivas.du.etx.ericsson.se,10,0>,
174                         {registered_name,net_kernel}},
175        {<madonna@chivas.du.etx.ericsson.se,11,0>,
176                         []},
177        {<madonna@chivas.du.etx.ericsson.se,12,0>,
178                         {registered_name,global_name_server}},
179        {<madonna@chivas.du.etx.ericsson.se,13,0>,
180                         {registered_name,auth}},
181        {<madonna@chivas.du.etx.ericsson.se,14,0>,
182                         {registered_name,rex}},
183        {<madonna@chivas.du.etx.ericsson.se,15,0>,
184                         []},
185        {<madonna@chivas.du.etx.ericsson.se,16,0>,
186                         {registered_name,file_server}},
187        {<madonna@chivas.du.etx.ericsson.se,17,0>,
188                         {registered_name,code_server}},
189        {<madonna@chivas.du.etx.ericsson.se,20,0>,
190                         {registered_name,user}},
191        {<madonna@chivas.du.etx.ericsson.se,38,0>,
192                         []}]
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197Ericsson AB                  erl_interface 3.13.2                  erl_call(1)
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