<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" }

'ROT13 in Linguine
'Programmed by Jeffry Johnston, 2005
1[-2?,-2~10:3,-2<65:2,-2<91:5,-2<97:2,-2<123:6]2
2[*-1=*-2,-1+1]1
3[*-3~0:4,*-3$,-3+1]3
4[-2$]0
5[-2+13,-2<91:2,-2-26]2
6[-2+13,-2<123:2,-2-26]2