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I apologize if this has already been answered, or if the answer is simpler than I realize, but I can't seem to figure out the following:

When I try to generate an md5 from a string, either with

echo -n "string" | md5sum | cut -f1 -d' '

or with

echo -n "string" | openssl md5

the result is not 32 characters, as I would expect, but rather 33 (using wc -c).

So, I have a few questions:

  1. Why do both md5sum and openssl add a trailing space?
  2. Is there another way to generate an md5 hash without a trailing newline or space?
  3. Does the trailing space really matter?

Thank you all in advance.

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Instead of using awk like in the answer below i would use tr like this: echo -n "string" | md5sum | cut -d " " -f 1 | tr -d "\n" . This will clear the new line character from the output. –  mnmnc Jan 9 '13 at 7:50

1 Answer 1

up vote 3 down vote accepted

It's 32 characters! The md5sum is adding a linefeed to the end. You can get rid of it like this:

% echo -n string | md5sum|awk '{print $1}'|wc -c
% echo -n $(echo -n string | md5sum|awk '{print $1}')|wc -c

or you could do it like this:

% echo -n $(md5sum <<< 'string'|awk '{print $1}')|wc -c

You can tell when one of the commands is adding a newline because the 32 character string will show up on its own line. If no newline is present it should always show up like this:

[prompt %] echo -n $(md5sum <<< 'string'|awk '{print $1}')
b80fa55b1234f1935cea559d9efbc39a[prompt %]
share|improve this answer
Thanks for the answer! Unfortunately, I don't have enough reputation to vote you up. For the sake of clarity though, I think I like echo -n $(echo -n "string" | openssl md5) –  Alex Krycek Jan 9 '13 at 5:12
Sure! That's the beauty of UNIX. There's more than one way to do everything! –  slm Jan 9 '13 at 5:14

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