How to check array doesn't contain line in bash scripting

Question

I am reading data from a file line by line and storing it to array, so that I can access later that array to compare with other files data.

Now, my input file has redundancy, how to add only unique lines to array. I need to check while adding to array itself?

Below is the code I am using to read data from file:

while read line
do
    //How to check array already contains this line???
        <Code to adding to array>
done <"$file"

What version of bash? How are you planning to use this array later? — Etan Reisner, Jul 22 '15 at 17:41
Duplicate: http://stackoverflow.com/questions/3685970/check-if-an-array-contains-a-value — Brian, Jul 22 '15 at 17:41
@springuser you should check to see if anyone asked the same trivial question previously. You'll enlighten yourself with wisdom of the ancients of StackOverflow. — msw, Jul 23 '15 at 04:40

anubhava · Answer 1 · 2015-07-23T04:32:10.713

0

You can use associative array for this:

declare -A ulines

while IFS= read -r line; do
   [[ ! ${ulines["$line"]} ]] && echo "$line" && ulines["$line"]=1
done < "$file"

This will print unique lines on stdout preserving original order in input file.

edited Jul 23 '15 at 04:32

answered Jul 22 '15 at 17:41

anubhava

it's changing the order of lines, how to avoid this, I want to retain order, in which file is read – SpringUser Jul 23 '15 at 03:18

1 Answers1