Re: GNU Parallel Bug Reports --tmux does not pass locale correctly (needed since tmux 2.2)

[Matti Niemenmaa]

On 2017-04-16 14:49, Ole Tange wrote:
> On Sat, Apr 15, 2017 at 9:04 PM, Matti Niemenmaa
> <address@hidden> wrote:
>
> > --tmux doesn't work for me at all as of tmux 2.2. The "Maximal used size of
> > command" is computed incorrectly and so no command can be run:
> >
> > $ parallel --tmux --show-limits echo ::: x
> > Maximal size of command: 131049
> > Maximal used size of command: -16
>
> Yup, it is clearly wrong.
>
> > $ LANG= LC_ALL= LC_CTYPE= tmux
> > tmux: need UTF-8 locale (LC_CTYPE) but have ANSI_X3.4-1968
>
> I compiled 2.3 from source and could not reproduce this.

My guess is that you have the en_US.UTF-8 locale installed, which tmux 
will default to. Check the output from 'locale -a': on my system 
en_US.utf8 is not listed.

> > The underlying cause within GNU parallel is that ::qqx is used to call tmux,
> > and ::qqx strips out locale information from the environment.
> >
> > Note that everything will seem to work if you have the en_US.UTF-8 locale
> > available, because tmux will fall back to that in the absence of locale
> > information. On my system that locale is not installed, which culminates in
> > the failure.
> >
> > Adding LC_CTYPE to @keep inside ::qqx fixes the issue.
>
> I am reluctant to copy $LC_CTYPE as I need the output from ::qqx to be
> predictable, and locales can change the output.
>
> So I suggest:
>
> @@ -4228,6 +4228,7 @@ sub qqx {
>      @address@hidden = @address@hidden;
>      local(%ENV);
>      %ENV = %env;
> +    $ENV{'LC_ALL'} = 'C';
>      if($Global::debug) {
>         return qx{ @_ && true };
>      } else {
>
> Will this work, too?

I'm afraid not. As commented at https://github.com/tmux/tmux/issues/815 
"tmux requires either en_US.UTF-8 to be available or a different UTF-8 
locale to be specified in LC_ALL." C is not a UTF-8 locale, so this does 
not fix the issue.

> (And if you can find a virtual machine image on which you can
> reproduce the error, please let me know.)
Any system without an en_US.UTF-8 locale should do it. Will a Docker 
image do for an example?

# docker pull base/devel  # Arch Linux
# docker run -i -t --entrypoint bash base/devel

(Inside the Docker container now:)

# pacman -Syu libevent
<snip>
# curl -LO 
https://github.com/tmux/tmux/releases/download/2.3/tmux-2.3.tar.gz
<snip>
# cd tmux-2.3
# ./configure && make
<snip>
# ./tmux
tmux: need UTF-8 locale (LC_CTYPE) but have ANSI_X3.4-1968

And to verify that GNU Parallel fails in these conditions:

# curl -LO http://ftpmirror.gnu.org/parallel/parallel-20170322.tar.bz2
# cd parallel-20170322
# ./configure && make
# PATH=../tmux-2.3:$PATH src/parallel --tmux --show-limits echo ::: x
sh: ps: command not found
Maximal size of command: 131049
Maximal used size of command: -16
<snip rest of output>

— Matti