parallel: Error: $XDG_CONFIG_DIRS can only contain [-a-z0-9_+,.%:/= ].

[Hans Yperman]

Hi,

Recent Ubuntus have the option to log in using active directory and sssd/realmd.  One consequence is my username containing the @ character as AD names are shaped username@domain, and hence so do my home folder and a few environment variables.  I expected this to cause mayhem, but everything seems to work nicely.  Except GNU parallel breaks because it has a whitelist for some environment variables, and @ isnt included.  

I assume the code in file parallel line 2925  is to blame.  I did a quick test by adding it to the latest download, and that indeed fixes it.

   sub test_safe_chars {

        my $var = shift;

        if($ENV{$var} =~ m{^[-a-z0-9_+,.%:/= ]*$}is) {

            # OK

        } else {

            unsafe_warn("\$$var can only contain [-a-z0-9_+,.%:/= ].");

        }

    }

I see no character limitations in the XDG spec:

https://specifications.freedesktop.org/basedir-spec/latest/

I don't know what characters are valid in a username.  The 2nd response from stackoverflow gives a whitelist from POSIX, but parallel already supports more:

https://serverfault.com/questions/73084/what-characters-should-i-use-or-not-use-in-usernames-on-linux

The realmd documentation for default-home shows it will by default contain an @

https://www.freedesktop.org/software/realmd/docs/realmd-conf.html

Thanks in advance for looking into this.  And of course, thanks for the parallel tool which has served me very well.

Some command line commands for demonstration:

$ parallel
parallel: Error: $XDG_CONFIG_DIRS can only contain [-a-z0-9_+,.%:/= ].

$ XDG_CONFIG_DIRS= parallel

parallel: Warning: Input is read from the terminal. You are either an expert

[SNIP]

$ parallel --version

GNU parallel 20231122

Copyright (C) 2007-2023 Ole Tange, http://ole.tange.dk and Free Software

Foundation, Inc.

License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>

[SNIP]

$ echo $XDG_CONFIG_DIRS

/home/hans.yperman@vliz.be/.config/kdedefaults:/etc/xdg/xdg-plasma:/etc/xdg

$ lsb_release  -a

No LSB modules are available.

Distributor ID: Ubuntu

Description:    Ubuntu 24.04.1 LTS

Release:        24.04

Codename:       noble