BASH Base64 Encode script not encoding right

Question

I am trying to get a base64 encode to work and output to a variable in a bash script. The regular cli syntax is:

echo -ne "\[email protected]\0mypass" | base64

But when I try putting this into a variable in a script it outputs, but a very small encoding, so I know it's not working. My code in the script is:

auth=$(echo -ne "\0$user@$host\0$pass" | base64);

I know it has something to do with the quotes, but I've tried a myriad of thing's with different quotes and singles and backslashes with no go.

Any thoughts?

EDIT: A bit more for the info. This should output with the user/pass/host above:

AG15dXNlckBteWhvc3QuY29tAG15cGFzcw==

But in the script it outputs:

LW5lIAo=

Answer 1

Different versions of echo behave very differently when you give them anything other than a plain string. Some interpret command options (like -ne), while some just print them as output; some interpret escape sequences in the string (even if not given a -e option), some don't.

If you want consistent behavior, use printf instead:

user=myuser
pass=mypass
host=myhost.com

auth=$(printf "\0%s@%s\0%s" "$user" "$host" "$pass" | base64)

As a bonus, since the password (and username and host) are in plain strings rather than the format string, it won't make a mess trying to interpret escape sequences in them (does your real password have a backslash in it?)