perl -MO=Deparse -e '$_="abcdef"; s/@{[s".."."gr]}\K$"//; print'
$_ = 'abcdef';
s[@{[s/.././gr];}\K$"][];
print $_;
-e syntax OK

##</code><code>##

perl -MO=Deparse -e '$_="abcdef"; s/@{[s".."."gr]}\K //; print'
$_ = 'abcdef';
s[@{[s/.././gr];}\K ][];
print $_;
-e syntax OK

##</code><code>##

perl -MO=Deparse -e '$_="abcdef"; s/@{[s".."."gr]}\K$"//; print'
$_ = 'abcdef';
s[@{[s/.././rg];}\K][$"];
print $_;
-e syntax OK

##</code><code>##

perl -MO=Deparse -e '$_="abcdef"; s/@{[s".."."gr]}\K //; print'
$_ = 'abcdef';
s[@{[s/.././rg];}][\\K ];
print $_;
-e syntax OK

##</code><code>##

#!perl -pl
s/@{[s".."."gr]}\K$"//
  
##</code><code>##

$_="abcdef";
s/@{[s".."."gr]}/$& /;print  #  "...abcdef"

$_="abcdef";
s/@{[s".."."gr]}//;print     #  "...abcdef"

$_="abcdef";
s/@{[s".."."gr]}\K //;print  #  "\K def"

##</code><code>##

#!perl -p
s/.(?0).|\K/ $&/