How to reference multiple string values in array in Shell script

Question

I am trying to store multiple string in for loop but it giving me unwanted answer. My code is :

#!/bin/bash
declare -a arr=("ps -ef | grep icsmpgum | grep $USER | grep -v grep | awk '{print $9,$8}' | awk '{print $1}'")

for i in "${arr[@]}"    
do
   echo "$i"
done

The output of

ps -ef | grep icsmpgum | grep $USER | grep -v grep | awk '{print $9,$8}' | awk '{print $1}'

is :

icsmpgum     
ABC
DEF

I want to refer to these 3 string values in for loop but after applying for loop as mention above it giving me output as :

Output :

ps -ef | grep icsmpgum | grep tsaprm1 | grep -v grep | awk '{print ,}' | awk '{print }'

How should I store these string values in variables ?

Tom Fenech · Accepted Answer · 2016-06-26 11:08:13Z

1

You need to use a command substitution, rather than quoting the command:

arr=( $(ps -ef | grep icsmpgum | grep $USER | grep -v grep | awk '{print $9,$8}' | awk '{print $1}') )

I suspect that this will work but there's a lot of further tidying up to be done; all the filtering that you want to do is possible in one call to awk:

arr=( $(ps -ef | awk -v user="$USER" '!/awk/ && /icsmpgum/ && $0 ~ user { print $9 }') )

As mentioned in the comments, there are potential risks to building an array like this (e.g. glob characters such as * would be expanded and you would end up with extra values in the array). A safer option would be to use a process substitution:

read -ra arr < <(ps -ef | awk -v user="$USER" '!/awk/ && /icsmpgum/ && $0 ~ user { print $9 }')

edited Jun 26, 2016 at 11:08

answered Jun 26, 2016 at 10:49

Tom Fenech

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1 Comment

Andreas Louv Over a year ago

This will make the output from the command substitution undergo pathname expansion - which might not be a problem - but to be safe one could use read -ra arr < <(ps ....)

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