/home/alex>perl -Mstrict -w -E 'say fileno(STDERR); say fileno("STDERR"); say fileno("stderr"); say fileno("foobar")//"undef"; say fileno($_)//"undef" for (qw( STDERR stderr foo ))'
Name "main::foobar" used only once: possible typo at -e line 1.
2
2
2
undef
2
2
undef


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