How can we assign value to an array variable from an external file?

Shell Programming and Scripting
1

is it possible to assign value to an array variable from an external file?? if yes then how??

I am using below code but its not working.

#!bin/bash
myarray[1] < file_name
echo ${mayarray[1]}
2

You read with the read command.

read var[1] < file
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3

use declare -a as per bash manual
For example, here is a script that places first thre fields in three array elements

 
declare -a arr
while read arr[1] arr[2] arr[3];
do
        echo "arr[1]="${arr[1]}
        echo "arr[2]="${arr[2]}
        echo "arr[3]="${arr[3]}
done < $1

my input file:

1 2 3 4 5
11 22 33 44 55

the output of the script :

 
!x.sh zz
arr[1]=1
arr[2]=2
arr[3]=3 4 5
arr[1]=11
arr[2]=22
arr[3]=33 44 55

Note how 'unassigned 4th and 5th imput fields are bundled into last argument to read

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4

suppose my files contains 5 different values separated by newline some what like

cat file
value1
value2
value3
value4
value5

what script should I use to assign these value to different element of an array variable.

5

in bash, you can do:

readarray ARRAY < file
6

Its not working.Script that I am using is

#!bin/bash
readarray myarray < sample
echo ${myarray[*]}

where sample is a file :

cat sample
value1
value2
value3
7

Firstly, you need to specify a correct shebang:

#!/bin/bash

Secondly, mapfile AKA readarray can only be used in bash 4, so check with

/bin/bash --version

--
Alternatively you could use:

myarray=( $(<sample) )
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