$x=eval($ENV{EDITOR});
print $x;

/bin/vi

$x=eval($ENV{QUOTE});
print $x;

$x = '

# Bad.
QUOTE="'" perl -wWe 'print eval $ENV{QUOTE}; print "$@"'
#  Can't find string terminator "'" anywhere before EOF at (eval 1) line 1.

# Bad.
QUOTE="'" perl -wWe 'print eval $ENV{QUOTE}; print "$@"'
#  Can't find string terminator "'" anywhere before EOF at (eval 1) line 1.

# Bad.
QUOTE="\'" perl -wWe 'print eval $ENV{QUOTE}; print "$@"'
#  Can't find string terminator "'" anywhere before EOF at (eval 1) line 1.

# Good
QUOTE="'''" perl -wWe 'print eval $ENV{QUOTE}; print "$@"'
# '

my $x = $ENV{QUOTE};
print "$xn";

# purposely broken
QUOTE='`rm system`'

$x=eval($ENV{QUOTE});
print $x;

$ EDITOR=/bin/vi perl -we '$x=eval($ENV{EDITOR}); print $x'
Bareword found where operator expected at (eval 1) line 1, near "/bin/vi"
    (Missing operator before vi?)
Unquoted string "vi" may clash with future reserved word at (eval 1) line 2.
Use of uninitialized value $x in print at -e line 1.

$ QUOTE=' perl -wle '$x=$ENV{QUOTE}; print $x'
'

$x = `$ENV{QUOTE}`