Global symbol "$x" requires explicit package name (did you forget to declare "my $x"?) at <location>

##</code><code>##

Bareword "xxx" not allowed while "strict subs" in use at <location>

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open(DATA, "<$tmpfile") or die "Can't open data";

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$ perl -E 'say for <DATA>'
Name "main::DATA" used only once: possible typo at -e line 1.
readline() on unopened filehandle DATA at -e line 1.
$ 

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$ perl -E 'say for <DATA>; __END__'
$ 

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perl -E '...'

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perl -Mstrict -Mwarnings -Mautodie -E '...'