Redirect output to a bash array

Question

I have a file containing the string

ipAddress=10.78.90.137;10.78.90.149

I'd like to place these two IP addresses in a bash array. To achieve that I tried the following:

n=$(grep -i ipaddress /opt/ipfile |  cut -d'=' -f2 | tr ';' ' ')

This results in extracting the values alright but for some reason the size of the array is returned as 1 and I notice that both the values are identified as the first element in the array. That is

echo ${n[0]}

returns

10.78.90.137 10.78.90.149

How do I fix this?

Thanks for the help!

Answer 1

This one works:

n=(`grep -i ipaddress filename | cut -d"=" -f2 | tr ';' ' '`)

EDIT: (improved, nestable version as per Dennis)

n=($(grep -i ipaddress filename | cut -d"=" -f2 | tr ';' ' '))

Answer 2

do you really need an array

bash

$ ipAddress="10.78.90.137;10.78.90.149"
$ IFS=";"
$ set -- $ipAddress
$ echo $1
10.78.90.137
$ echo $2
10.78.90.149
$ unset IFS
$ echo $@ #this is "array"

if you want to put into array

$ a=( $@ )
$ echo ${a[0]}
10.78.90.137
$ echo ${a[1]}
10.78.90.149

@OP, regarding your method: set your IFS to a space

$ IFS=" "
$ n=( $(grep -i ipaddress file |  cut -d'=' -f2 | tr ';' ' ' | sed 's/"//g' ) )
$ echo ${n[1]}
10.78.90.149
$ echo ${n[0]}
10.78.90.137
$ unset IFS

Also, there is no need to use so many tools. you can just use awk, or simply the bash shell

#!/bin/bash
declare -a arr
while IFS="=" read -r caption addresses
do
 case "$caption" in 
    ipAddress*)
        addresses=${addresses//[\"]/}
        arr=( ${arr[@]} ${addresses//;/ } )
 esac
done < "file"
echo ${arr[@]}

output

$ more file
foo
bar
ipAddress="10.78.91.138;10.78.90.150;10.77.1.101"
foo1
ipAddress="10.78.90.137;10.78.90.149"
bar1

$./shell.sh
10.78.91.138 10.78.90.150 10.77.1.101 10.78.90.137 10.78.90.149

gawk

$ n=( $(gawk -F"=" '/ipAddress/{gsub(/\"/,"",$2);gsub(/;/," ",$2) ;printf $2" "}' file) )
$ echo ${n[@]}
10.78.91.138 10.78.90.150 10.77.1.101 10.78.90.137 10.78.90.149

Answer 3

A variation on a theme:

$ line=$(grep -i ipaddress /opt/ipfile)
$ saveIFS="$IFS"    # always save it and put it back to be safe
$ IFS="=;"
$ n=($line)
$ IFS="$saveIFS"
$ echo ${n[0]}
ipAddress
$ echo ${n[1]}
10.78.90.137
$ echo ${n[2]}
10.78.90.149

If the file has no other contents, you may not need the grep and you could read in the whole file.

$ saveIFS="$IFS"
$ IFS="=;"
$ n=$(</opt/ipfile)
$ IFS="$saveIFS"

Answer 4

A Perl solution:

n=($(perl -ne 's/ipAddress=(.*);/$1 / && print' filename))

which tests for and removes the unwanted characters in one operation.