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=

Are you sure $user, $host and $pass are set? Sorry for a stupid question, but gotta rule out the obvious stuff. Cause in my test it works allright, see pastebin.com/mSR64eEh — favoretti
– favoretti, Commented Sep 5, 2012 at 22:23
Dang IT!! Yeah their set, I do this just before doing that: user="myuser" pass="mypass" host="myhost.com" — jfreak53
– jfreak53, Commented Sep 5, 2012 at 22:26
Saw my pastebin? Edited my comment, not sure before or after you answered :) — favoretti
– favoretti, Commented Sep 5, 2012 at 22:27
Yeah I looked at it before, that's what's wierd, I have that exact same thing and no go :( — jfreak53
– jfreak53, Commented Sep 5, 2012 at 22:28
@jordanm - totally agree, although many beginners don't really feel the difference :) — favoretti
– favoretti, Commented Sep 5, 2012 at 22:46

favoretti · Accepted Answer · 2012-09-05 22:34:41Z

30

Ok, I'll add this as an answer for the records's sake:

Problem was in having /bin/sh as a default interpreter shell, which I assume, in this case was dash.

Test script used:

#!/bin/bash
user=myuser
pass=mypass
host=myhost.com

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

echo $auth

Results:

[51][00:33:22] vlazarenko@alluminium (~/tests) > echo -ne "\[email protected]\0mypass" | base64 
AG15dXNlckBteWhvc3QuY29tAG15cGFzcw== 

[52][00:33:42] vlazarenko@alluminium (~/tests) > bash base64.sh
AG15dXNlckBteWhvc3QuY29tAG15cGFzcw== 

[53][00:33:46] vlazarenko@alluminium (~/tests) > dash base64.sh  
LW5lIAo=

answered Sep 5, 2012 at 22:34

favoretti

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6 Comments

jfreak53 Over a year ago

Correct, I just found out it was linking to Dash. So what is the difference and what gives if I may ask?

favoretti Over a year ago

dash is POSIX only + a few berkeley extensions. It somewhat resembles ksh, but has also not all the features and is far less featured than bash.

jordanm Over a year ago

@jfreak53 In this case, it was probably the non-POSIX options to echo.

jfreak53 Over a year ago

Hmm, show's you what I know, Dash is the default sh shell for Ubuntu 11 and beyond then :) thanks for the help.

Barmar Over a year ago

Use printf instead of echo and you shouldn't have to worry about differences between shells.

|

Gordon Davisson · Accepted Answer · 2012-09-05 23:52:09Z

14

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?)

answered Sep 5, 2012 at 23:52

Gordon Davisson

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