CODEWITHSUNDEEP
ioerlangstdoutstdin
InDaPond
InDaPond

Reputation: 572

Erlang read from StdIn without prompt

I just read Erlang's IO module, all the input functions start with a prompt().

I have a program A which pipes it's output to my Erlang program B, therefore making A's stdout to B's stdin.

How can I just read that stdIn in a loop, since I get a msg every Xms.

what I want is something like this

loop()->
  NewMsg = readStdIn() %% thats the function I am looking for
  do_something(NewMsg),
  loop.

Upvotes: 0

Views: 677

Answers (1)

7stud
7stud

Reputation: 48599

I just read Erlang's IO module, all the input functions start with a prompt().

It looks like you can use "" for the prompt. Reading line oriented input from stdin:

-module(my).
-compile(export_all).

read_stdin() ->
    case io:get_line("") of
        eof ->
            init:stop(); 
        Line ->
            io:format("Read from stdin: ~s", [Line]),
            read_stdin()
    end.

In a bash shell:

~/erlang_programs$ erl -compile my.erl
my.erl:2: Warning: export_all flag enabled - all functions will be exported

~/erlang_programs$ echo -e "hello\nworld" | erl -noshell -s my read_stdin
Read from stdin: hello
Read from stdin: world
~/erlang_programs$

See Erlang How Do I...write a unix pipe program in Erlang?

Upvotes: 3

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