Store values from arrays in config-file to variables

Question

I've got the following problem: I got a config-file (written in bash) with multiple arrays, the amount of these arrays is different from config to config. Each array contains three values.

declare -a array0
array0=(value1 value2 value3)  
#  
declare -a array1  
array1=(value1 value2 value3)  
#  
declare -a array2  
array2=(value1 value2 value3)

Now, this config file is sourced into the main bash script. I want to go from array to array and store the values into single variables. My actual solution:

for ((i=0;i=2;i++))  
do  
 if [ "$i" = 0 ]  
 then  
  wantedvalue1="${array0["$i"]}"  
 fi  
 if [ "$i" = 1 ]  
 then  
  wantedvalue2="${array0["$i"]}"  
 fi  
 if [ "$i" = 2 ]  
 then  
  wantedvalue3="${array0["$i"]}"  
 fi  
done

I guess, this will work for one specific array. But how can I tell the script to analyze every array in the config file like this?
Thanks for any help!

it's possible that there will be 50 or more arrays.. I really don't want to place 50 for loops in my code. — dnc
– dnc, Commented Oct 28, 2014 at 11:22
Perhaps it's worth providing some more context here. What exactly are you trying to achieve in the end? Why do you need to make separate variables like this anyway? — Tom Fenech
– Tom Fenech, Commented Oct 28, 2014 at 11:39

Community · Accepted Answer · 2017-05-23 10:33:19Z

1

You can find the arrays in your environment via set. This extracts the names of the arrays which have exactly three elements:

set | sed -n 's/^\([_A_Za-z][_A-Za-z0-9]*\)=(\[0]=.*\[2]="[^"]*")$/\1/p'

(The number of backslashes depends on your sed dialect. This worked for me on Debian, where backslashed parentheses are metacharacters for grouping, and bare parentheses are matched literally.)

I don't really see why you want to use a loop to extract just three elements, but the wacky indirect reference syntax in bash kind of forces it here.

for array in $(set |
  sed -n 's/^\([_A_Za-z][_A-Za-z0-9]*\)=(\[0]=.*\[2]="[^"]*")$/\1/p'); do
    for((i=0, j=1; i<3; ++i, ++j)); do
         k="$array[$i]"
         eval wantedvalue$j=\'${!k}\'
    done
    :
    : code which uses the wantedvalues here
done

It would be a tad simpler if you just used another array for the wantedvalues. Then the pesky eval could be avoided, too.

edited May 23, 2017 at 10:33

CommunityBot

11 silver badge

answered Oct 28, 2014 at 11:53

tripleee

192k37 gold badges318 silver badges367 bronze badges

Sign up to request clarification or add additional context in comments.

3 Comments

Paul Bastide Over a year ago

note - Triplee uses the nested loop suggested above (to close the loop)

dnc Over a year ago

finally I didn't use the loop - just the set/sed combination, this worked fine for me

tripleee Over a year ago

@PaulBastide That's trivial. The substance is in obtaining the array names, and in the trickery in using them indirectly.

Collectives™ on Stack Overflow

Store values from arrays in config-file to variables

1 Answer 1

3 Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

3 Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related