BASH: How to store commands with variables into a new variable?

Question

I want to store the ith line of a file (filename stored in variable filename) into a new variable called line where:

filename=$2
i=$1

let's say for this sake i=1 and filename=names.txt):

line="$(sed '1q;d' names.txt)"

How would I store the actual filename and i variable?

does this work also for the sed example? ie sed '$iq:d' $filename)" because I get an error for the $i — Marisa
– Marisa, Commented May 25, 2015 at 0:19

CS Pei · Accepted Answer · 2015-05-25 00:21:49Z

2

Is this what you want?

line=$(sed "${i}q;d" $filename)

For example,

$filename="a.txt"

i=1

line=$(sed "${i}q;d" $filename)

echo $line 
aaa

a.txt like this:

aaa
bbb

The key is that you need double quotes for ${i} otherwise you will get errors.

answered May 25, 2015 at 0:21

CS Pei

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3 Comments

Hmm that gives me an error..however that is the output I want

the 1q;d must be in single quotes? not sure if that affects it. ie must be sed '1q;d' names.txt

what environment do you have? what kind of error do you get?