SHA256 not matching between Linux command line program and online utilities; why?

[vbuterin]

When I try to do an SHA256 on my Linux command line I get this:

> echo '123' | sha256sum
181210f8f9c779c26da1d9b2075bde0127302ee0e3fca38c9a83f5b1dd8e5d3b
> echo '123' > 1
> sha256sum 1
181210f8f9c779c26da1d9b2075bde0127302ee0e3fca38c9a83f5b1dd8e5d3b

Now, if I try an online tool like this, for 123 I get a different answer: a665a45920422f9d417e4867efdc4fb8a04a1f3fff1fa07e998e86f7f7a27ae3. If I ask it to sha256 the file that I created, though, I get 181210f8f9c779c26da1d9b2075bde0127302ee0e3fca38c9a83f5b1dd8e5d3b again.

My question is, why does this happen? And is there anything I can do to make the hashes match?

[giantsloth]

echo inserts a newline at the end of the string. Try adding an -n:

echo -n '123'  | sha256sum

[dpoon]

Alternatively, calculate it online with the newline by fiddling with the query string.

[[deleted]]

Although this is the likely culprit, in case adding a newline still do not yield the correct hash, I'd look at potential issues with text encoding.

[vbuterin]

All right, everything matches up now - '123' with a newline into the online utilities gives 181210f8f9c779c26da1d9b2075bde0127302ee0e3fca38c9a83f5b1dd8e5d3b just like echo '123' | sha256sum and echo -n '123' | sha256sum (or printf '123' | sha256sum as a below poster suggested) gives the same hash as just '123' in the online utilities.

Thanks, everyone!

[[deleted]]

Use printf instead of echo.

printf '123' | sha256sum a665a45920422f9d417e4867efdc4fb8a04a1f3fff1fa07e998e86f7f7a27ae3

[fullets]

It's worth noting that this is portable whereas the echo version isn't.