Computation Problem - Shell Programming and Scripting

PradeepRed · #1 05-11-2006

Hi Folks

I have a file with the following sample input
919416586748,1200,31200
919416283619,3521,33521
919416811900,2440,64940
919416576012,13670,43670

Now i want to subtract the second value (where , is field separator) from the third value and display the output as follows

919416,30000
919416,30000
919416,62500
919416,30000

i wrote a simple program

Code:

for var in `cat 1`
do
a1=`echo $var | cut -d"," -f1|cut  -c1-6`
a2=`echo $var | cut -d"," -f2`
a3=`echo $var | cut -d"," -f3`
a4=`expr $a3 - $a2`
echo "$a1,$a4" >> 2
done

This works fine for files which are of small size. But my input file has over 1 million entries and hence is taking a damn long time to process.
Can anybody recommend a much faster method for the same?

Thanks in advance
Regards

Perderabo · #2 05-11-2006

How about:
awk -v FS=, -v OFS=, '{print substr($1,1,6),$3-$2}' < datafile

futurelet · #3 05-11-2006

Quote:

awk -v FS=, -v OFS=, '{print substr($1,1,6),$3-$2}' < datafile

awk 'BEGIN{FS=OFS=","}{print substr($1,1,6),$3-$2}' datafile

PradeepRed · #4 05-11-2006

Thanks a lot folks

Both the queries worked. I really need to brush up on the awk command. This is the second time where a one line awk command has bailed me out where i had spent hours using some inefficient scripts.

Regards

More UNIX and Linux Forum Topics You Might Find Helpful
Thread	Thread Starter	Forum	Replies	Last Post
problem with dd command or maybe AFS problem	Anta	Shell Programming and Scripting	0	08-25-2006 07:10 AM
SSH Problem auth problem	budrito	UNIX for Advanced & Expert Users	1	03-17-2004 07:12 AM

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search
Display Modes
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode