[GTALUG] tr: Illegal byte sequence

[William Park]

> >     for i in $(seq 32); do
> >         printf '%x' $((RANDOM % 94 + 33))
> >     done | xxd -r -ps

Even more portable would be 

    echo -e $(for i in $(seq 32); do printf '\\x%x' $((RANDOM % 94 + 33)); done)

-- 
William Park <opengeometry at yahoo.ca>

On Mon, Oct 01, 2018 at 10:16:44AM -0400, Giles Orr wrote:
> Thanks to everyone that responded - this has been very helpful.
> 
> So it seems that this _is_ locale-related: Hugh's explanation points out
> that not all two-byte strings are valid characters under UTF-8, and that
> would break 'tr'.  Thus the change to 'C' fixing the problem.  That really
> helped me understand the problem, thanks.
> 
> I want a command line solution, so GRC's website doesn't work for me.  And
> I don't think it's a good idea to take a password from another source: it's
> unlikely GRC stores generated passwords and then tries to hack the
> associated IP or web browser with it, but isn't it better to do this
> yourself so only you know the outputted password?
> 
> As for 'pwgen', it has precisely the same problem as 'apg' - it's not
> installed by default as Stewart mentioned.
> 
> Someone asked what these passwords used for.  We have to create accounts on
> many services (most of which don't support any authentication method except
> passwords) and give those accounts to other people to use.  It's my intent
> that the recipient should change the password to something more to their
> liking.  But many people don't: they just let their web browser memorize
> the password and then let us reset the password when they "forget" it by
> changing browsers.  At least this way I know they have a relatively random
> and secure password to start with, usually much better than what they would
> have changed it to.
> 
> 
> On Thu, 27 Sep 2018 at 15:30, William Park via talk <talk at gtalug.org> wrote:
> 
> > If Mac has recent Bash, then you could probably use $RANDOM variable
> > which picks a number from 0-32767 every time you read it.  From top of
> > my head,
> >     for i in $(seq 32); do
> >         printf '%x' $((RANDOM % 94 + 33))
> >     done | xxd -r -ps
> > That will give you full 94 character range you want.
> > --
> > William Park <opengeometry at yahoo.ca>
> >
> > On Wed, Sep 26, 2018 at 10:43:46AM -0400, Giles Orr via talk wrote:
> > > I wrote a random password generator shell script, the core of which is
> > this
> > > one-liner:
> > >
> > > dd if=/dev/urandom bs=1 count=256 2>/dev/null | tr -dc
> > > 'A-Za-z0-9!@$%^&*(){}[]=+-_/?\|~`' | head -c 32
> > >
> > > The very ugly string 'A-Za-z0-9!@$%^&*(){}[]=+-_/?\|~`' is the ALLOWED
> > > values.  The two counts are replaced by variables, the first 'count='
> > > needing to be a lot bigger than the final '-c <number>' which is the
> > length
> > > of the password generated.  The size difference is necessary because 'tr'
> > > throws away a lot of values.
> > >
> > > I've never had a problem with this on Linux, but on a Mac under some
> > > circumstances we get:
> > >
> > >     tr: Illegal byte sequence
> > >
> > > My coworker, who's also using the script, always got that error.  It
> > seems
> > > to come down to locale settings.  Mine by default are:
> > >
> > > $ locale
> > > LANG="en_CA.UTF-8"
> > > LC_COLLATE="en_CA.UTF-8"
> > > LC_CTYPE="en_CA.UTF-8"
> > > LC_MESSAGES="en_CA.UTF-8"
> > > LC_MONETARY="en_CA.UTF-8"
> > > LC_NUMERIC="en_CA.UTF-8"
> > > LC_TIME="en_CA.UTF-8"
> > > LC_ALL=
> > >
> > > My co-worker's settings are:
> > >
> > > LANG="en_US.UTF-8"
> > > LC_COLLATE="en_US.UTF-8"
> > > LC_CTYPE="en_US.UTF-8"
> > > LC_MESSAGES="en_US.UTF-8"
> > > LC_MONETARY="en_US.UTF-8"
> > > LC_NUMERIC="en_US.UTF-8"
> > > LC_TIME="en_US.UTF-8"
> > > LC_ALL="en_US.UTF-8"
> > >
> > > A reliable fix (so far ...):
> > >
> > >     $ export LC_CTYPE=C
> > >     $ export LC_ALL=C
> > >     $ dd if=/dev/urandom bs=1 count=256 2>/dev/null | tr -dc
> > > 'A-Za-z0-9!@$%^&*(){}[]=+-_/?\|~`' | head -c 32
> > >     z%V;d9uZfWLTgsT*J]Bz`mAmA
> > >
> > > I'd really like to understand what the problem is, why 'tr' barfs, and
> > what
> > > the 'locale' settings have to do with this.  Thanks.
> > >
> > > (Should anyone have arguments against this as a method of password
> > > generation, I'll entertain those too.  And yes, I'm aware of 'apg' but
> > it's
> > > not readily available for Mac and this is much lighter weight.)
> > >
> > > --
> > > Giles
> > > https://www.gilesorr.com/
> > > gilesorr at gmail.com
> >
> > > ---
> > > Talk Mailing List
> > > talk at gtalug.org
> > > https://gtalug.org/mailman/listinfo/talk
> > ---
> > Talk Mailing List
> > talk at gtalug.org
> > https://gtalug.org/mailman/listinfo/talk
> >
> 
> 
> -- 
> Giles
> https://www.gilesorr.com/
> gilesorr at gmail.com