Setting A Variable in A While Loop in Bash

Question

I need help setting the output of the grep command below as a variable for each line.

    while read line; do 
        grep -oP '@\K[^ ]*' <<< $line
    done < tweets

Above displays what I want like this:

lunaluvbad

Mags_GB

And so on...

However if I would do something like:

    while read line; do
        usrs="grep -oP '@\K[^ ]*' <<< $line"
    done < tweets

    echo $usrs

It displays weird result, and certainly not the result I'm looking for. I need $usrs to display what I had mentioned above. Example:

lunaluvbad

Mags_GB

Sven Marnach · Accepted Answer · 2014-02-05 21:54:46Z

2

No need for a loop at all. grep will loop over the lines of the input anyway:

usrs=$(grep -oP '@\K[^ ]*' tweets)

answered Feb 5, 2014 at 21:54

Sven Marnach

608k123 gold badges966 silver badges865 bronze badges

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

3 Comments

RydallCooper Over a year ago

This almost displays what I want, but the output is not displayed on its own line. Every word needs to be on its own line. Have any ideas?

tom Over a year ago

@RydallCooper Use quotes when you print the variable: echo "$usrs"

Sven Marnach Over a year ago

@RydallCooper: If you just want the output, grep -oP '@\K[^ ]*' tweets is all you need. If you want to do further processing on the output, tell us what you are trying to do.

anubhava · Accepted Answer · 2014-02-05 21:50:18Z

2

Make use of BASH arrays and command substitution like this:

users=()
while read -r line; do
    users+=( "$(grep -oP '@\K[^ ]*' <<< "$line")" )
done < tweets

OR else using process substitution:

users=()
while read -r line; do
    users+=( "$line" )
done < <(grep -oP '@\K[^ ]*' tweets)

printf "%s\n" "${users[@]}"

answered Feb 5, 2014 at 21:50

anubhava

790k67 gold badges603 silver badges671 bronze badges

Collectives™ on Stack Overflow

Setting A Variable in A While Loop in Bash

2 Answers 2

3 Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

3 Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related