In Oneiric beta2, env variable $LOGNAME is blank/null

[Chris]

This is a new install done this morning, and fully updated twice today. The problem came to my attention when a backup script failed, which was traced to the fact that $LOGNAME variable was null.

I understand that the $LOGNAME variable "should not be relied on as it can be changed" however I'm sure a great number of backup scripts have used it over years since it was introduced in UNIX III. No previous Ubuntu releases have had a problem as far as I'm aware.

I originally asked a question on Launchpad as I wasn't sure if this was a bug:
https://answers.launchpad.net/ubuntu/+source/bash/+question/172882
however the respondent~andrew-woodhead666 demonstrated that his $LOGNAME variable was _not_ blank, even though the two systems should be equivalent.

As a final test update manager was run and the system was rebooted, and it was verified that $LOGNAME was still null.

ProblemType: Bug
DistroRelease: Ubuntu 11.10
Package: bash 4.2-0ubuntu4
ProcVersionSignature: Ubuntu 3.0.0-12.19-generic 3.0.4
Uname: Linux 3.0.0-12-generic i686
NonfreeKernelModules: nvidia
ApportVersion: 1.23-0ubuntu2
Architecture: i386
Date: Sun Oct 2 00:16:19 2011
InstallationMedia: Ubuntu 11.10 "Oneiric Ocelot" - Beta i386 (20110921.2)
ProcEnviron:
 SHELL=/bin/bash
 PATH=(custom, user)
 LANG=en_AU.UTF-8
 LANGUAGE=en_AU:en
SourcePackage: bash
UpgradeStatus: No upgrade log present (probably fresh install)

[Chris (fabricator4)]

I believe this is related to core-utils, as per the man page on #LOGNAME

[Louis-Dominique Dubeau (ldd)]

I've also encountered this bug on Ubuntu 11.10.

However, I found the following:

1. If I log in from a text console or if I invoke login manually, LOGNAME is set properly.

2. If I log in using X, then LOGNAME is not set.

Preliminary investigation leads me to believe that the problem is with lightdm. The file src/session.c contains the following code:

gboolean
session_start (Session *session)
{
    User *user;

    g_return_val_if_fail (session != NULL, FALSE);
    g_return_val_if_fail (session->priv->authentication != NULL, FALSE);
    g_return_val_if_fail (session->priv->command != NULL, FALSE);

    g_debug ("Launching session");

    user = pam_session_get_user (session->priv->authentication);
    session_set_env (session, "PATH", "/usr/local/bin:/usr/bin:/bin");
    session_set_env (session, "USER", user_get_name (user));
    session_set_env (session, "USERNAME", user_get_name (user)); // FIXME: Is this required?
    session_set_env (session, "HOME", user_get_home_directory (user));
    session_set_env (session, "SHELL", user_get_shell (user));

    return SESSION_GET_CLASS (session)->start (session);
}

LOGNAME is absent. There does not seem to be any other opportunity to set LOGNAME in for a new session.

This is what is installed on my machine:

$ apt-cache policy lightdm
lightdm:
  Installed: 1.0.1-0ubuntu6
  Candidate: 1.0.1-0ubuntu6
  Version table:
 *** 1.0.1-0ubuntu6 0
        500 http://us.archive.ubuntu.com/ubuntu/ oneiric/main amd64 Packages
        100 /var/lib/dpkg/status

[Chris (fabricator4)]

Fixed in LightDM since Oneiric release