[tlug] Code Query-Bittorrent Scripts

[Mark Sargent <powderkeg@example.com>]

Hi All,

I'm not a programmer and wish to query some of the below code, which is
the only part I don't understand. Cheers

Mark Sargent.

Code Being Queried:

BEGIN { srand() }
	{ names[NR]=$0 }
	END {
	    j=int(NR*rand());	   


found here,

http://lue.dyn.dhs.org/2005/20050708135201.html

Full Code:

#!/bin/sh
#bt.offer: circulate offered torrents

howmany=0
offerall=0
loopctrl=0

case $1 in
    all) offerall=1 ;;
    [0-9]*) howmany=$1 ;;
    "") howmany=7 ;;
esac

# first, remove what's already being offered 
cd /usr/local/bt || exit 1
if [ -f $HOME/.bt/offer/offered ]; then
    rm $(cat $HOME/.bt/offer/offered)
    rm $HOME/.bt/offer/offered
fi

# two special cases
#1): remove all offered torrents
if [ $howmany -eq 0 ]; then
    exit 3
fi
#2): offer all the torrents that I have
if [ $offerall -eq 1 ]; then
    cd $HOME/.bt/offer || exit 2
    ls *.torrent > offered
    cp *.torrent /usr/local/bt/
    exit 0
fi

# offer another batch 
cd $HOME/.bt/offer || exit 2
i=0
while [ $loopctrl -eq 0 ]  
do
    torrent=$(ls *.torrent |
    awk '
	BEGIN { srand() }
	{ names[NR]=$0 }
	END {
	    j=int(NR*rand());
	    if (j<1) j=j+10;
	    if (j>NR) j=NR;
	    print names[j]
	}
    ' )
    echo "$torrent" >> offered
    i=$(expr "$i" + 1)
    if [ $i -ge $howmany ]; then
	loopctrl=1
    fi
    sleep 1s
done
sort offered | uniq > /tmp/$$
mv /tmp/$$ offered
for torrent in `cat offered`
do
    cp "$torrent" /usr/local/bt/"$torrent"
done