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The Twelve Days of Programmers Shell Script
George Ruban

Once I had the inexplicable urge to create a Unix shell (sh) script that prints "The Twelve Days of Christmas". So I did. Here it is, in clear-text form, and in an encoded form (ROT-13 encoding) which decodes itself as it runs, so you can mail it to people who will have to run it to find out what it does.

To run it,

  1. Go to a Unix system
  2. Save the program (a set of the lines in monospace format) as a file, called, for example program
  3. Make the file executable, by typing
    chmod +x program
  4. Execute it, simply by typing the program name,


# Shell script which prints The Twelve Days of Programmers
# Written by George Ruban, 12-24-97
# reproduce freely, with this notice
ordinal="first second third fourth fifth sixth seventh eighth ninth tenth \
    eleventh twelfth"
for gift in \
    "a shell script that prints this poem." \
    "two core dumps," \
    "three broken master makes," \
    "four fatal errors," \
    "five golden files..." \
    "six spaghetti-code subroutines," \
    "seven segmentation violations," \
    "eight unreproducible bugs," \
    "nine annoyed customers," \
    "ten terrified sales-reps," \
    "eleven exultant competitors," \
    "twelve terminated programmers,"
    poem="$gift N $poem"
    num=`echo $ordinal | cut -d' ' -f $n`
    echo "On the" $num "day of Christmas, my hacker gave to me N" \
        $poem | tr N '\12'
    if [ $n -eq 1 ] ; then poem="and $poem" ; fi
    sleep $n
    n=`expr $n + 1`


# Written by George Ruban, 12-24-97
# reproduce freely, with this notice

o="svefg frpbaq guveq sbhegu svsgu fvkgu friragu rvtugu avagu gragu \
    ryriragu gjrysgu" ; n=1
for g in "n furyy fpevcg gung cevagf guvf cbrz." "gjb pber qhzcf," \
    "guerr oebxra znfgre znxrf," "sbhe sngny reebef," "svir tbyqra svyrf..." \
    "fvk fcnturggv-pbqr fhoebhgvarf," "frira frtzragngvba ivbyngvbaf," \
    "rvtug haercebqhpvoyr ohtf," "avar naablrq phfgbzref," \
    "gra greevsvrq fnyrf-ercf," "ryrira rkhygnag pbzcrgvgbef," \
    "gjryir grezvangrq cebtenzzref..."
    p="$g N $p"
    m=`echo $o | cut -d' ' -f $n`
    echo "Oa gur $m qnl bs Xznf, zl unpxre tnir gb zr N" \
        $p | tr '[a-z]N' '[n-z][a-m]\12'
    if [ $n -eq 1 ]; then p="naq $p"; fi
    sleep $n
    n=`expr $n + 1`
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