[SOLVED] storing array from awk in bash

ghantauke · 11-24-2010, 08:55 AM

i'm using awk inside bash. i've got an array in awk called arrayinawk. everytime i call another awk command in bash i have to keep creating arrayinawk to work with it. is there anyway i can store arrayinawk in bash and just call the stored value next time i use awk?

catkin · 11-24-2010, 09:08 AM

You can certainly pass the array back to bash by having awk write a bash array assignment command and having bash eval the awk output. AFAIK awk's -v option only allows passing single values but the container bash could put awk statements to load the arrayin the awk script.

ghantauke · 11-24-2010, 11:06 AM

Quote:

Originally Posted by catkin

You can certainly pass the array back to bash by having awk write a bash array assignment command and having bash eval the awk output. AFAIK awk's -v option only allows passing single values but the container bash could put awk statements to load the arrayin the awk script.

i don't really follow that ^^

ghantauke · 11-24-2010, 11:31 AM

I'm using awk inside bash. I'm working with the file called test which has the following content.

kill bill
epic deal
blonde chick
linux questions

I store the data into an array called dataarray.

awk '{dataarray[$1]=$2}' test

Later on when I want to call this array in another awk command line. So I want to store dataarray into a bash array and call it in the other awk command line. How can I do this? Thanks in advance.

Tinkster · 11-24-2010, 05:25 PM

What he's saying is that there's no simple way.

grail · 11-24-2010, 07:14 PM

This seems particularly convoluted? Is there a reason you cannot either extend the first awk script to perform the task of the one you wish to utilize the array?

Or maybe even just create the initial array in bash (v4 does associative arrays) and then use bash to perform all your tasks?

Tinkster · 11-24-2010, 07:49 PM

I merged your two threads; don't go producing dupes because you don't
like the answers in the original.

catkin · 11-24-2010, 08:32 PM

Quote:

Originally Posted by Tinkster

I merged your two threads; don't go producing dupes because you don't
like the answers in the original.

Thanks Tinkster, that simplifies things

ghantauke · 11-25-2010, 06:28 AM

Quote:

Originally Posted by grail

This seems particularly convoluted? Is there a reason you cannot either extend the first awk script to perform the task of the one you wish to utilize the array?

Or maybe even just create the initial array in bash (v4 does associative arrays) and then use bash to perform all your tasks?

I cannot extend the awk script to perform the whole task because I need to use bash commands on the array later on.

For the second question I simple don't know how to store the values in bash array without using awk. It'd help if you could give me a hint on how to do it.

ghantauke · 11-25-2010, 06:53 AM

I tried the following for assigning the file to an associative array in bash. It doesn't work.

lines=$(wc -l < file)
for ((i=1;lines>=i;i++))
do
$A=$(head -$i file| tail -1 | awk '{print $1}')
$B=$(head -$i file| tail -1 | awk '{print $2}')
arraytest[$A]=$B
done

The error message.

bash: =kill: command not found
bash: =bill: command not found
bash: =epic: command not found
bash: =deal: command not found
bash: =blonde: command not found
bash: =chick: command not found
bash: =linux: command not found
bash: =questions: command not found

I can't see where I'm going wrong.

GrapefruiTgirl · 11-25-2010, 07:12 AM

I tried doing this:

Code:

awk '$1!=""{printf("%s","dataarray[\""$1"\"]=\""$2"\";")}END{print}' test

which produces this:

Code:

dataarray["kill"]="bill";dataarray["epic"]="deal";dataarray["blonde"]="chick";dataarray["linux"]="questions";

which you can eval:

Code:

root@reactor: eval $(awk '$1!=""{printf("%s","dataarray[\""$1"\"]=\""$2"\";")}END{print}' test)

Executes without error; however, the array does not seem to be created properly:

Code:

root@reactor: echo ${dataarray[*]}
questions
root@reactor:

And in any event, even if this works after someone points out what I'm doing wrong, I agree with catkin - there's probably an easier way to either use just awk, or just bash. IF not, that's fine, but please humor us: can you give us a larger view of the entire process requirements here? I.e. you want to process this file into an array in awk (and presumably do something to the data) but then you also want the same array, in bash.

I think there must be a compromise or different perspective that maybe can be taken, but to suggest, we need to know what's going on in the larger picture.

ghantauke · 11-25-2010, 07:23 AM

Quote:

Originally Posted by catkin

You can certainly pass the array back to bash by having awk write a bash array assignment command and having bash eval the awk output. AFAIK awk's -v option only allows passing single values but the container bash could put awk statements to load the arrayin the awk script.

i'm not sure what mean by "having bash eval the awk output"
if you mean using eval command like the following:
eval array[0]=awk...........
then it doesn't work since eval only works on variables and not on commands like awk.

catkin · 11-25-2010, 07:32 AM

You want A= not $A= (think of the $ as meaning "the value of") and you need to declare the array as associative

Code:

#!/bin/bash

# Configure script environment
set -o nounset
unalias -a

# Read data
declare -A array
while read index data
do
    indexes+=( $index )
    array[$index]=$data
done < LQ-846269.txt

# Show array content
for ((i=0; i<${#indexes[*]}; i++))
do
    index=${indexes[i]}
    echo "array[$index] is ${array[$index]}"
done

catkin · 11-25-2010, 07:36 AM

Quote:

Originally Posted by GrapefruiTgirl

And in any event, even if this works after someone points out what I'm doing wrong ...

Thanks for explaining that Sasha

The missing step was declaring dattaarray as associative:

Code:

c@CW8:~$ dataarray["kill"]="bill";dataarray["epic"]="deal";dataarray["blonde"]="chick";dataarray["linux"]="questions";
c@CW8:~$ echo ${dataarray[*]}
questions
c@CW8:~$ unset dataarray
c@CW8:~$ declare -A dataarray
c@CW8:~$ dataarray["kill"]="bill";dataarray["epic"]="deal";dataarray["blonde"]="chick";dataarray["linux"]="questions";
c@CW8:~$ echo ${dataarray[*]}
bill chick questions dea

GrapefruiTgirl · 11-25-2010, 07:38 AM

Aha! A measly declare?

Thanks for that (I thought declare was optional - in this case, it is definitely not).