CODEWITHSUNDEEP
bash
Nick Knowlson
Nick Knowlson

Reputation: 7426

Bash substring with pipes and stdin

My goal is to cut the output of a command down to an arbitrary number of characters (let's use 6). I would like to be able to append this command to the end of a pipeline, so it should be able to just use stdin.

echo "1234567890" | your command here 
# desired output: 123456

I checked out awk, and I also noticed bash has a substr command, but both of the solutions I've come up with seem longer than they need to be and I can't shake the feeling I'm missing something easier.

I'll post the two solutions I've found as answers, I welcome any critique as well as new solutions!

Solution found, thank you to all who answered!

It was close between jcollado and Mithrandir - I will probably end up using both in the future. Mithrandir's answer was an actual substring and is easier to view the result, but jcollado's answer lets me pipe it to the clipboard with no EOL character in the way.

Upvotes: 20

Views: 20678

Answers (5)

Nick Knowlson
Nick Knowlson

Reputation: 7426

I had come up with:

echo "1234567890" | ( read h; echo ${h:0:6} )

and 

echo "1234567890" | awk '{print substr($0,1,6)}'

But both seemed like I was using a sledgehammer to hit a nail.

Upvotes: 6

potong
potong

Reputation: 58488

This might work for you:

printf "%.6s" 1234567890
123456

Upvotes: 2

eduffy
eduffy

Reputation: 40232

If your_command_here is cat:

% OUTPUT=t9p8uat4ep
% cat <<<${OUTPUT:0:6}
t9p8ua

Upvotes: 0

jcollado
jcollado

Reputation: 40414

What about using head -c/--bytes?

$ echo t9p8uat4ep | head -c 6
t9p8ua

Upvotes: 7

Mithrandir
Mithrandir

Reputation: 25387

Do you want something like this:

echo "1234567890" | cut -b 1-6

Upvotes: 41

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