<b_jonas> perl -e for $e ("i","u"){ $f="bin/date$e"; open my$i,"<",$f or die "error open $f r"; local$/; $s=<$i> or die; $s=~s/"\\+%Y/\\${1:+-d "\\$1"} $&/ or die; open $o,">",$f or die "error open $f w: $!"; print $o $s or die; close $o or die; print "OK $f\\n" }

#!/bin/sh
exec date ${1:+-d "$1"} "+%Y-%m-%d %H:%M:%S.%N %z %Z %B %-e %A %G-W%V-%u"