Shell Programming and Scripting

I have two files:

fileA
a,b,c,10,apple
a,b,c,20,orange
a,b,c,10,grape
d,e,f,5,pear
d,e,f,100,pear
x,y,z,15,lemon
x,y,z,20,apple
x,y,z,30,grape

fileB
a,b,c,20
d,e,f,100
x,y,z,30

If col1=col1,col2=col2 and col3=3 of fileA to fileB, then take value in 4th col of fileB and replace it in fileA...so I get this:

desired output:
a,b,c,20,apple
a,b,c,20,orange
a,b,c,20,grape
d,e,f,100,pear
x,y,z,30,lemon
x,y,z,30,apple
x,y,z,30,grape

is while within while my only option or does someone know an awk solution that can do this faster, especially if the files will be very large?

Thanks.
G

So no one knows how to do this without a while of 20K records (fileB) with another 200K records (fileA)? Would be even better if someone knows how to just work with fileA and for each record in fileA apply the highest value in col4 to all records with identical first 1-3 columns (key) since that's all I'm using fileB is for right now.

You can try this:

Code:

awk -F, 'NR==FNR{a[$1$2$3]=$4;next}
a[$1$2$3]{$4=a[$1$2$3]}
1' OFS="," fileB fileA

Use nawk or /usr/xpg4/bin/awk on Solaris.

Regards

Wow! Thanks. This looks so simple compared to a while in a while. I'll give it a try and see. You rock!

Franklin, can you explain a little about why / how this works?
I'm a little lost.

Code:

awk -F, 'NR==FNR{a[$1$2$3]=$4;next}
a[$1$2$3]{$4=a[$1$2$3]}
1' OFS="," fileB fileA

Code:

NR==FNR{a[$1$2$3]=$4;next}

NR==FNR -> If we read fileB fill an element of an array a indexed with $1$2$3 with the value of $4

The other lines affect for fileA:

Code:

a[$1$2$3]{$4=a[$1$2$3]}

If the array has an index with the value $1$2$3 assign the value of the array to $4

Code:

1

Validated as true, the default action is to print the current line in the buffer similar to

Code:

{print}

Regards