http://www.linuxquestions.org/questions/programming-9/bash-shell-script-split-array-383848/?posted=1#post3270996

And see:

IP=1.2.3.4; IP=(${IP//./ }); Rev=${IP[3]}.${IP[2]}.${IP[1]}.${IP[0]}

Thanks! I hadn't known about the IFS internal variable.

IFS=":"; declare -a Array=($*)

echo "Array[0]=${Array[0]}"
echo "Array[1]=${Array[1]}"
echo "Array[2]=${Array[2]}"
echo "Array[3]=${Array[3]}"

You can use variable variables inside the loop so you don't have to repeat each if block.

To see how they work, try this:
VAR1=abc
abc=123
echo ${!VAR1}

Inside your while read loop you could do something like this:

fred=""
for VAR in col1 col2 col3 col4; do
if [ -n "${!VAR} ] ; then
fred=$fred"${!VAR}"
fi
done

I have the following code to read in a file an process accordingly :

#/tmp/test.txt looks like this :
# 0-1|0-2|0-3|0-4
# 1-1||1-3|1-4
# |2-2|2-3|2-4
# 3-1|3-2||3-4

FILENAME=$1; #input filename
OIFS=$IFS;
IFS='|';

while read col1 col2 col3 col4
do
if [ -n "$col1" ]; then
fred="col1 = '$col1', ";
else
fred="";
fi
if [ -n "$col2" ]; then
fred=$fred"col2 = '$col2', ";
else
fred=$fred;
fi
if [ -n "$col3" ]; then
fred=$fred"col3 = '$col3', ";
else
fred=$fred;
fi
if [ -n "$col4" ]; then
fred=$fred"col4 = '$col4'";
else
fred=$fred;
fi
echo $fred;
done <$FILENAME

#the output looks like this
col1 = '0-1', col2 = '0-2', col3 = '0-3', col4 = '0-4'
col1 = '1-1', col3 = '1-3', col4 = '1-4'
col2 = '2-2', col3 = '2-3', col4 = '2-4'
col1 = '3-1', col2 = '3-2', col4 = '3-4'

I want to know - can I substitute 'col1 - col4' for a variable, since there is about 40 fields per line on the "real" file and to do more or less the same validation repetitively seems pointless.

any suggestions would be appreciated.

thanks

I'm sticking with "I build robots" though, it's definitely the more fun answer and usually results in better conversation.

But robot lawn mowers can mosey around the yard all week. They needn't be powerful, and so they also needn't be very robustly built. They needn't start on the first pull; they don't need a big honking blade; they don't need to be made out of metal. Made in a large quantity, a serviceable, low-end robot mower should cost around $100 (not including the battery, which should cost another $50, and not including the perimeter wire, which should cost around $30).

I think the reason available robot mowers cost a bundle is that there are lots of manual mowers out there that cost $400, making a $1000 price tag for a robot mower (certainly preferable to a manual mower) seem less ridiculous.

I got so peved about this that I made my own robot lawn mower from a child's ride-on toy (a Power Wheels Barbie Jeep). If you wanna see it, there's a video on youtube: http://www.youtube.com/watch?v=zuXqg4q3cQ8