Bash script to parse the output of a command

Question

For instance command below

# sha512sum /home/bin.tar

gives this output:

7847a537b5db4434c075f18319caf12090cb0f19640190cbdf27e28a7b40b568127dfe9ec1c06604a87887ad403b618edeb42d1c41366b7a3e91d47b8d754ea4  /home/bin.tar

How can I assign only hash part of this output to a variable in bash in order to compare the calculated hash with other hash in another variable?

What I have tried only assigns the parts that matches condition in grep (I only need the first part):

#! /bin/sh

RESULT="$(sha512sum /home/bin.tar | grep -o " /home/bin.tar")"

echo "Result:"

echo $RESULT

exit

Output

Result: 
/home/bin.tar

score 3 · Accepted Answer · answered Sep 21 '16 at 13:23

3

This should do it:

RESULT="$(sha512sum /home/bin.tar | cut -d' ' -f1)"

or

RESULT="$(sha512sum /home/bin.tar)"
RESULT="${RESULT%% *}"

or

RESULT="$(sha512sum /home/bin.tar | grep -o '^[^ ]*')"

answered Sep 21 '16 at 13:23

redneb

That was very quick and directly the answer. Thank you! – mtekeli Sep 21 '16 at 13:27

score 2 · Answer 2 · answered Sep 21 '16 at 13:23

2

Do it with awk

RESULT="$(sha512sum /home/bin.tar | awk '{print $1}')"

Or using plain bash arrays. Just run these commands over the console.

md5Output=( $(sha512sum /home/bin.tar) ); printf "%s\n" ${md5Output[0]}

answered Sep 21 '16 at 13:23

Inian

2 Answers2