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Old 04-24-2009, 04:48 PM   #1
RyudoBlaze
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Registered: Apr 2009
Posts: 4

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Change column value with AWK


Hi everyone,

what I have is a script that calculates an amount

amt=`echo $price*$qty*1.13 | bc`

after this is calculated, I need to somehow use AWK to add this value to the second column of my file. The file looks like this:

dan:13760
ricky:1235
mitch:123

I have a variable "$name" that has been entered by the user, say "dan" is entered I need to search through the file and add 13760 + $amt. so far I have this but its not working... and I think its too complicated for this task

awk -F":" '$1~/'$name'/ {total=$2+$amt; printf "%s:%i\n",$1,$total}' $a && awk -F":" ' ! $1~/'$name'/ { print $0}' $a > file

so what im trying to do is make an output and then just redirect it to the file...

but there has to be an easier way of doing this? like by just adding $2 with $amt or something? or use sed?

any help is greatly appreciated
 
Old 04-24-2009, 05:45 PM   #2
jlinkels
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Registered: Oct 2003
Location: Bonaire
Distribution: Debian Wheezy/Jessie/Sid, Linux Mint DE
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I assume that you have a shell script which calculates the value for $amt somehow.

Then in this shell script you call:
Code:
awk -v amt=$amt -v name=dan -f add.awk names.txt
Now you can use the variables name and amt in the awk script. Although you can put it on one line, it is easier to create an .awk file for it.

names.txt:
Code:
dan:13760
ricky:1235
mitch:123
add.awk
Code:
BEGIN{
FS=":"
}
{
if (name == $1)
        print "was: " $1 " " $2 " becomes: "$1 " " $2+amt
else
        print "was: " $1 " " $2 " remains: "$1 " " $2
}
Calling:
Code:
awk -v amt=1000 -v name=dan -f add.awk names.txt
This yields:
Code:
was: dan 13760 becomes: dan 14760
was: ricky 1235 remains: ricky 1235
was: mitch 123 remains: mitch 123
This is not exactly the output format you need, but I wrote it like this for clarity. You can easy adapt it to your preferences.

To pipe everyting into a file, you can append "> outputfile" to the awk command.

Remember there is NO way that inside and awk script you can recognize a bash variable. All values have to be passed thru the command line using the form -v var1=foo -v var2=bar.. etc.

jlinkels
 
Old 04-25-2009, 04:05 AM   #3
RyudoBlaze
LQ Newbie
 
Registered: Apr 2009
Posts: 4

Original Poster
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Thanks alot for the help! I finished my script
 
  


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