[erlang-bugs] ioi:columns bug

Joe Armstrong <>
Wed May 29 15:02:26 CEST 2013

io:columns() does not work in a process spawned from the command line


test() ->
    io:format("~p~n", [io:columns()]).

When I run this in a shell it works

2> c(bug).
3> bug:test().

But not from the command line

> erl -s bug test
Erlang R16B (erts-5.10.1) [source] [64-bit] [smp:4:4]
[async-threads:10] [hipe] [kernel-poll:false]

Eshell V5.10.1  (abort with ^G)
1> {error,enotsup}

Something is strange - the group leader of a process launched from the
command line is different to the shell group leader. But I can do io:format
from a command launched from the command line --- what's happening here?


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