# #1137654

my $find = "20150518<";          # assumes that a date-like value not 
+followed by a '<' is not what you seek
my $replace = "18 May 2015";
while(my $line = <DATA>)
{
      if($line =~ $find) {    # select lines to print, unless you want
+ all lines * Note1
        s/$find/$replace/g;  # UPDATE: but the slash-g is utterly unne
+cessary 
            print $line;         # as it would act only on single line
+s in this case
    }
}

# * Note1: acknowledged: you want all lines.  (another update)


=head output

20150518<114319747011000001>,
20150518<bulkbull3>,


=cut


__DATA__
20150518<114319747011000001>,
20150518230002,< >,
917696706652,01,
,
52727,
rch,,
admin,,
01,21314,,
bulkpull2,,
20150518<bulkbull3>,
[download]