/etc/skel/.profile does not detect bash properly

# ~/.profile: executed by the command interpreter for login shells.
# This file is not read by bash(1), if ~/.bash_profile or ~/.bash_login
# exists.
# see /usr/share/doc/bash/examples/startup-files for examples.
# the files are located in the bash-doc package.

# the default umask is set in /etc/profile; for setting the umask
# for ssh logins, install and configure the libpam-umask package.
#umask 022

# if running bash
if [ -n "$BASH_VERSION" ]; then
    # include .bashrc if it exists
    if [ -f "$HOME/.bashrc" ]; then
        . "$HOME/.bashrc"
    fi
fi

# set PATH so it includes user's private bin if it exists
if [ -d "$HOME/bin" ] ; then
    PATH="$HOME/bin:$PATH"
fi

So if I run bash in posix mode or as /bin/sh.

antarus@goats5 /etc/skel $ env -i /bin/sh -c 'echo $BASH_VERSION'
4.2.24(1)-release
antarus@goats5 /etc/skel $ env -i bash --posix -c 'echo $BASH_VERSION'
4.2.24(1)-release

This means when lightdm-session-wrapper sources the users $HOME/.profile (created from /etc/skel) it will also sources their $HOME/.bashrc. lightdm-session-wrapper runs as posix sh, and not bash. Sourcing a .bashrc as posix sh does not work well.

antarus@goats5 ~/antarus $ /bin/sh
sh-4.2$ source ~/.bashrc
sh: `break-posix-sh': not a valid identifier
antarus@goats5 ~/antarus $ grep 'break-posix-sh' ~/.bashrc
function break-posix-sh() {

Functions cannot have dashes in them in posix, but can in bash, for example.

If you replace the .profile login with something like:

if ! shopt -oq posix; then
    # include .bashrc if it exists
    if [ -f "$HOME/.bashrc" ]; then
        . "$HOME/.bashrc"
    fi
fi

It seems to work properly.

DISTRIB_CODENAME=precise
DISTRIB_DESCRIPTION="Ubuntu 12.04.1 LTS"
DISTRIB_ID=Ubuntu
DISTRIB_RELEASE=12.04

antarus@goats5 ~/antarus $ apt-cache policy bash
bash:
  Installed: 4.2-2ubuntu2
  Candidate: 4.2-2ubuntu2
  Version table:

If lightdm cannot source my .bashrc, I cannot login. Also, thousands of my users cannot login.

-A