Is the md5sum linux command working right?

Question

According to Wikipedia, the md5 sum of an empty string is d41d8cd98f00b204e9800998ecf8427e

I confirmed this with my md5 library

However, when I run

echo "" | md5sum

in my linux shell, I get 68b329da9893e34099c7d8ad5cb9c940 -

In fact, none of my hashes match the output of the md5sum command.

Any thoughts on this discrepancy?

Answer 1

With that command, you are calculating the md5sum of a single newline character. Try instead:

echo -n "" | md5sum

Answer 2

You must eliminate the new line that echo produces

$ echo -n '' | md5
d41d8cd98f00b204e9800998ecf8427e

Answer 3

Try:

echo -n | md5sum

Without the '-n', echo outputs a newline, which md5sum duly processes.

Answer 4

use the more portable printf

printf "" | md5sum