C:\>set PERL5OPT=-w -Mstrict
C:\>perl -e"print $x"
Global symbol "$x" requires explicit package name (did you forget to declare "my $x"?) at -e line 1.
Execution of -e aborted due to compilation errors.
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C:\>set PERL5OPT=-w -Mstrict=refs,subs
C:\>perl -e"print $x"
Name "main::x" used only once: possible typo at -e line 1.
Use of uninitialized value $x in print at -e line 1.
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C:\>perl -le "my $str = q{zxcv}; if ( $str -~ m/some pattern/i ) { print $str; }"
Use of uninitialized value $_ in pattern match (m//) at -e line 1.
Argument "zxcv" isn't numeric in subtraction (-) at -e line 1.
zxcv