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Language bourne shell
(small pieces loosely joined)
| Date: | 03/14/06 |
| Author: | anonymous |
| URL: | n/a |
| Comments: | 0 |
| Info: | n/a |
| Score: |  (2.89 in 9 votes) |
#!/bin/sh
################################################################################
# Major things to notice:
# A) this infinite loop has no exit. no need for a Haskell port to your PDP-11
# to play with (somewhat) lazy infinite streams
# B) redirection can ocurr not only for simple commands, but also the control
# structures. By connecting several control structures with pipes, we do
# not have the usual algol-style hierarchical control flow, but rather a
# script which is composed of communicating concurrent processes
# C) a process in the *middle* of a pipeline (in this case, "bottle") can
# determine termination just as easily as the head or tail processes
################################################################################
# of possible interest:
# 0) HERE documents may expand variables
# 1) the case structure may match with file globbing wildcards
# 2) variable expansion may take defaults
# 3) expressions may involve regex matching as well as arithmetic
################################################################################
singverses() {
read N0bottles; read n0bottles
echo "$N0bottles of beer on the wall, $n0bottles of beer."
while { read Nbottles; read nbottles; } do
cat <<-EOV # 0
Take one down and pass it around, $nbottles of beer on the wall.
$Nbottles of beer on the wall, $nbottles of beer.
EOV
done
echo "Go to the store to buy some more, $n0bottles of beer on the wall."
}
countdown() {
n=$1
while true; do # [A]
echo $n
n=`expr $n - 1`
done
}
bottle() {
while read n; do
case $n in # 1
-*) exit ;;
0) echo "No more bottles" ;;
1) echo "1 bottle" ;;
24) echo "A two-four" ;;
*) echo "$n bottles" ;;
esac
done | while read n; do # [B]
echo $n
echo $n | tr "[A-Z]" "[a-z]"
done
}
beers=${1:-99} # 2
if [ `expr "$beers" : "[0-9]*$"` -eq 0 ]; then # 3
echo "Usage: $0 [number of beers]"
exit 1
else
countdown $beers | bottle | singverses # [C]
fi
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Alternative Versions
| Version | Author | Date | Comments | Rate |
|---|---|---|---|---|
| 1 | Craig J. Copi | 04/20/05 | 0 | |
| Gramatically correct | Jeff Popp | 06/14/07 | 2 | |
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