Shell Programming and Scripting

Hi

i want to create a loop to set variable from a file

when you do a awk '{ print $1 }' that print the first field that cool

so i would like something like

xa=1

loop
awk '{ print $xa }'
xa=xa+1
enloop

so here is my actual code is not working i have the error
awk: Field $() is not correct.

The input line number is 1.
The source line number is 1.

####################################
#my code

CTR=1
xa=1
while [ "$nbidinst" != "$nbidinstlast" ]
do
id[$CTR]=`cat temp | awk '{ print $xa }'`
CTR=CTR+1
xa=xa+1
nbidinst=`cat temp | awk '{ print $xa }'`
echo $nbidinst
echo $id[$CTR]
done
}

Awk can't access variables defined in the shell script unless you explicitly pass them:

Code:

id[$CTR]=`awk -v xa=$xa '{ print $xa }' temp`
...
nbidinst=`awk -v xa=$xa '{ print $xa }' temp`

xa=1

loop
nawk -v a="$xa" '{ print $a }'
xa=xa+1
enloop

looking at a tutorial and trying to understand this variable business with awk, I tried

awk ' BEGIN { print a > "testfile" } ' a=$PWD

but testfile is always empty.

What is wrong with this?

a variable being passed a variable the way above is NOT available in the 'BEGIN' block, but everywhere else in awk.


a variable being passed a variable the way below is available throughout awk [including the 'BEGIN' block].

Code:

awk -v a=$PWD ' BEGIN { print a > "testfile" } '

P.S. If using Solaris' "old", ONLY the FIRST option exists

You can use this syntax to access shell variables inside Awk

Code:

nbidinst=`awk -v '{ print "'"$xa"'" }' temp`