file:read_file/1 missing 1st binary of /dev/stdin which comes from Unix pipe

[pojiro]

Describe the bug

I wrote a escript like following,

#!/usr/bin/env escript
main(_) ->
  {ok, Binary} = file:read_file("/dev/stdin"),
  io:format("~s", [binary_to_list(Binary)]).

Then use it with Unix pipe like following

LC_ALL=c ping -c 1 example.com | escript pipe_test_with_file_read.erl

Above didn't put anything, but when changed the ping count option from 1 to 2, the result was printed without 1st ping.

LC_ALL=c ping -c 2 example.com | escript pipe_test_with_file_read.erl
64 bytes from 93.184.215.14 (93.184.215.14): icmp_seq=2 ttl=54 time=129 ms

--- example.com ping statistics ---
2 packets transmitted, 2 received, 0% packet loss, time 1001ms
rtt min/avg/max/mdev = 126.080/127.448/128.817/1.368 ms

To Reproduce

It's the same as the Bug section.

Expected behavior

It would be nice to be able to use /dev/stdin directly in a Unix pipe.
I'm an Elixir programmer, this issue comes from elixir-lang/elixir#13780

Affected versions

I just confirmed this with 27.0.1 .

Additional context

Nothing.

[garazdawi]

If you add -noinput to you escript it will work. That is:

#!/usr/bin/env escript
%%! -noinput
main(_) ->
  {ok, Binary} = file:read_file("/dev/stdin"),
  io:format("~s", [binary_to_list(Binary)]).

[pojiro]

Thank you!