The s/// substitution /r modifier is only available from Perl version 5.14 onwards. kennethk has shown how to use the /r modifier, but if you have a Perl version prior to 5.14 and wish to preserve the original string, use method B below:
c:\@Work\Perl>perl -wMstrict -le
"my $adate = '2017-01-29 11:30:07.370';
;;
my $A_new = $adate =~ s/(\d{4})-(\d{2})-(\d{2})\s(\d{2}):(\d{2})(.*)/
+$2-$3-$1 $4:$5/r;
print qq{A: new '$A_new' old '$adate'};
;;
(my $B_new = $adate) =~ s/(\d{4})-(\d{2})-(\d{2})\s(\d{2}):(\d{2})(.*
+)/$2-$3-$1 $4:$5/;
print qq{B: new '$B_new' old '$adate'};
"
A: new '01-29-2017 11:30' old '2017-01-29 11:30:07.370'
B: new '01-29-2017 11:30' old '2017-01-29 11:30:07.370'
In both cases, the original string,
$adate in this case, is left unchanged. If you do not mind changing this variable, just use a normal
$string =~ s/// substitution.
Give a man a fish: <%-{-{-{-<