G'day gflohr,

I'm a bit late to the party on this one; however, I wondered if fileno might help you: 

$input = <STDIN> if defined fileno(STDIN);

[download]

I don't have docker to test but it seems to work equally well on both UNIX-like and MSWin OSes.

Cygwin:

ken@titan ~/tmp
$ perl -E 'my $input = "none"; $input = <STDIN> if defined fileno(STDI
+N); say $input'
qwerty
qwerty


ken@titan ~/tmp
$ perl -E 'my $input = "none"; close STDIN; $input = <STDIN> if define
+d fileno(STDIN); say $input'
none

ken@titan ~/tmp

[download]

Win10 - cmd.exe:

C:\Users\ken\tmp>perl -E  "my $input = 'none'; $input = <STDIN> if def
+ined fileno(STDIN); say $input"
qwerty
qwerty


C:\Users\ken\tmp>perl -E  "my $input = 'none'; close STDIN; $input = <
+STDIN> if defined fileno(STDIN); say $input"
none

C:\Users\ken\tmp>

[download]

Win10 - PowerShell:

PS C:\Users\ken\tmp> perl -E 'my $input = "none"; close STDIN; eval { 
+defined fileno(STDIN) } and do { $input = <STDIN> }; say $input'
none
PS C:\Users\ken\tmp> perl -E 'my $input = "none"; $input = <STDIN> if 
+defined fileno(STDIN); say $input'
qwerty
qwerty

PS C:\Users\ken\tmp> perl -E 'my $input = "none"; close STDIN; $input 
+= <STDIN> if defined fileno(STDIN); say $input'
none
PS C:\Users\ken\tmp>

[download]

And in case you were wondering, those are using different Perl installations for Cygwin and Win10: 

This is perl 5, version 30, subversion 0 (v5.30.0) built for cygwin-th
+read-multi
This is perl 5, version 30, subversion 0 (v5.30.0) built for MSWin32-x
+64-multi-thread

[download]

You don't need v5.30; that's just what I have installed. I suspect the guts of that code would work on pretty much any Perl 5.

— Ken

In reply to Re: Docker Container Started With Docker-Compose and <STDIN> by kcott
in thread Docker Container Started With Docker-Compose and <STDIN> by gflohr

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