Terminal colors etc -- adjust to missing /etc/skel files in user's home dir (`.profile`, `.bashrc`, `.bash_logout`)?

[consideRatio]

When linux users are created, they get files copied to their home directory copied from /etc/skel. These files aren't available in the image's default home directory, and even if they were, they would typically get replaced by a mounted home directory not bootstrapped with the files.

Due to this, we won't get colors in the terminals for example, and terminal headings are different.

Without /etc/skel files in home dir	With /etc/skel files in home dir

How files are executed

• Bash startup files

Login shells

Login shells will run two files, /etc/profile and optionally one of three possible profile files in the user's home directory.

1. /etc/profile
   1. /etc/bash.bashrc is sourced by /etc/profile
2. The first of any ~/.bash_profile, ~/.bash_login, and ~/.profile
   1. ~/.bashrc is sourced by /etc/skel/.profile, and ~/.bash_profile files typically does that as well if they are defined.

Change idea

Since /etc/skel files won't get copied, should we try to get them invoked if no files are available in the home directory?

I'm thinking about the following change:

# Default to using /etc/skel/.profile and /etc/skel/.bashrc if not in the user's
# home directory.
USER root
RUN echo ". /etc/bash.bashrc-skel-appendix" >> /etc/bash.bashrc
COPY bash.bashrc-skel-appendix /etc/bash.bashrc-skel-appendix
USER ${NB_USER}

# /etc/skel files should have been copied to a user's home directory, but if the
# user's home directory is mounted for example it may not contain files initially
# copied from /etc/skel. This can lead to terminals without colors etc.
#
# This script is made to be sourced from the end of /etc/bash.bashrc in order to
# default to source files from /etc/skel as a fallback to missing files in the
# home directory.
#
# ref: https://github.com/pangeo-data/pangeo-docker-images/issues/574.
#

# ~/.bash_profile, ~/.bash_login, or ~/.profile are defined, it doesn't make
# sense to fallback to /etc/skel/.profile, so then return.
[ -f "$HOME/.bash_profile" ] && return
[ -f "$HOME/.bash_login" ] && return
[ -f "$HOME/.profile" ] && return

# /etc/skel/.profile directly sources ~/.bashrc if defined, so we first check if
# it isn't, and then sources /etc/skel/.bashrc instead.
#
if [ ! -f "$HOME/.bashrc" ]; then
    . /etc/skel/.bashrc

    # --------------------------------------------------------------------------
    # The section below is adjusted from an Ubuntu 22.04 /etc/skel/.bashrc file
    # in order to tweak how PS1 was set. This influences the terminal prompt and
    # title.
    #
    # CHANGES:
    # - removed "#" from the line with force_color_prompt=yes
    # - removed "@\h" from PS1's prompt section
    # - removed "\u@\h: " from the PS1's xterm title section
    # --------------------------------------------------------------------------

    # uncomment for a colored prompt, if the terminal has the capability; turned
    # off by default to not distract the user: the focus in a terminal window
    # should be on the output of commands, not on the prompt
    force_color_prompt=yes

    if [ -n "$force_color_prompt" ]; then
        if [ -x /usr/bin/tput ] && tput setaf 1 >&/dev/null; then
            # We have color support; assume it's compliant with Ecma-48
            # (ISO/IEC-6429). (Lack of such support is extremely rare, and such
            # a case would tend to support setf rather than setaf.)
            color_prompt=yes
        else
            color_prompt=
        fi
    fi

    if [ "$color_prompt" = yes ]; then
        PS1='${debian_chroot:+($debian_chroot)}\[\033[01;32m\]\u\[\033[00m\]:\[\033[01;34m\]\w\[\033[00m\]\$ '
    else
        PS1='${debian_chroot:+($debian_chroot)}\u:\w\$ '
    fi
    unset color_prompt force_color_prompt

    # If this is an xterm set the title to dir
    case "$TERM" in
    xterm*|rxvt*)
        PS1="\[\e]0;${debian_chroot:+($debian_chroot)}\w\a\]$PS1"
        ;;
    *)
        ;;
    esac
fi


# Now run /etc/skel/.profile as it wasn't in the user's home directory.
. /etc/skel/.profile

Result without PS1 changes	Result with PS1 changes

/etc/profile content reference

Called first in bash login shells. Calls /etc/bash.bashrc and then things in /etc/profile.d.

cat /etc/profile

# /etc/profile: system-wide .profile file for the Bourne shell (sh(1))
# and Bourne compatible shells (bash(1), ksh(1), ash(1), ...).

if [ "${PS1-}" ]; then
  if [ "${BASH-}" ] && [ "$BASH" != "/bin/sh" ]; then
    # The file bash.bashrc already sets the default PS1.
    # PS1='\h:\w\$ '
    if [ -f /etc/bash.bashrc ]; then
      . /etc/bash.bashrc
    fi
  else
    if [ "$(id -u)" -eq 0 ]; then
      PS1='# '
    else
      PS1='$ '
    fi
  fi
fi

if [ -d /etc/profile.d ]; then
  for i in /etc/profile.d/*.sh; do
    if [ -r $i ]; then
      . $i
    fi
  done
  unset i
fi

/etc/bash.bashrc content reference

cat /etc/bash.bashrc

# System-wide .bashrc file for interactive bash(1) shells.

# To enable the settings / commands in this file for login shells as well,
# this file has to be sourced in /etc/profile.

# If not running interactively, don't do anything
[ -z "$PS1" ] && return

# check the window size after each command and, if necessary,
# update the values of LINES and COLUMNS.
shopt -s checkwinsize

# set variable identifying the chroot you work in (used in the prompt below)
if [ -z "${debian_chroot:-}" ] && [ -r /etc/debian_chroot ]; then
    debian_chroot=$(cat /etc/debian_chroot)
fi

# set a fancy prompt (non-color, overwrite the one in /etc/profile)
# but only if not SUDOing and have SUDO_PS1 set; then assume smart user.
if ! [ -n "${SUDO_USER}" -a -n "${SUDO_PS1}" ]; then
  PS1='${debian_chroot:+($debian_chroot)}\u@\h:\w\$ '
fi

# Commented out, don't overwrite xterm -T "title" -n "icontitle" by default.
# If this is an xterm set the title to user@host:dir
#case "$TERM" in
#xterm*|rxvt*)
#    PROMPT_COMMAND='echo -ne "\033]0;${USER}@${HOSTNAME}: ${PWD}\007"'
#    ;;
#*)
#    ;;
#esac

# enable bash completion in interactive shells
#if ! shopt -oq posix; then
#  if [ -f /usr/share/bash-completion/bash_completion ]; then
#    . /usr/share/bash-completion/bash_completion
#  elif [ -f /etc/bash_completion ]; then
#    . /etc/bash_completion
#  fi
#fi

# sudo hint
if [ ! -e "$HOME/.sudo_as_admin_successful" ] && [ ! -e "$HOME/.hushlogin" ] ; then
    case " $(groups) " in *\ admin\ *|*\ sudo\ *)
    if [ -x /usr/bin/sudo ]; then
	cat <<-EOF
	To run a command as administrator (user "root"), use "sudo <command>".
	See "man sudo_root" for details.
	
	EOF
    fi
    esac
fi

# if the command-not-found package is installed, use it
if [ -x /usr/lib/command-not-found -o -x /usr/share/command-not-found/command-not-found ]; then
	function command_not_found_handle {
	        # check because c-n-f could've been removed in the meantime
                if [ -x /usr/lib/command-not-found ]; then
		   /usr/lib/command-not-found -- "$1"
                   return $?
                elif [ -x /usr/share/command-not-found/command-not-found ]; then
		   /usr/share/command-not-found/command-not-found -- "$1"
                   return $?
		else
		   printf "%s: command not found\n" "$1" >&2
		   return 127
		fi
	}
fi

/etc/skel content reference

ls -alh /etc/skel/

total 20K
drwxr-xr-x 2 root root 4.0K Aug  8 14:07 .
drwxr-xr-x 1 root root 4.0K Aug 21 09:03 ..
-rw-r--r-- 1 root root  220 Jan  6  2022 .bash_logout
-rw-r--r-- 1 root root 3.7K Jan  6  2022 .bashrc
-rw-r--r-- 1 root root  807 Jan  6  2022 .profile

cat .profile

# ~/.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

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

cat .bashrc

# ~/.bashrc: executed by bash(1) for non-login shells.
# see /usr/share/doc/bash/examples/startup-files (in the package bash-doc)
# for examples

# If not running interactively, don't do anything
case $- in
    *i*) ;;
      *) return;;
esac

# don't put duplicate lines or lines starting with space in the history.
# See bash(1) for more options
HISTCONTROL=ignoreboth

# append to the history file, don't overwrite it
shopt -s histappend

# for setting history length see HISTSIZE and HISTFILESIZE in bash(1)
HISTSIZE=1000
HISTFILESIZE=2000

# check the window size after each command and, if necessary,
# update the values of LINES and COLUMNS.
shopt -s checkwinsize

# If set, the pattern "**" used in a pathname expansion context will
# match all files and zero or more directories and subdirectories.
#shopt -s globstar

# make less more friendly for non-text input files, see lesspipe(1)
[ -x /usr/bin/lesspipe ] && eval "$(SHELL=/bin/sh lesspipe)"

# set variable identifying the chroot you work in (used in the prompt below)
if [ -z "${debian_chroot:-}" ] && [ -r /etc/debian_chroot ]; then
    debian_chroot=$(cat /etc/debian_chroot)
fi

# set a fancy prompt (non-color, unless we know we "want" color)
case "$TERM" in
    xterm-color|*-256color) color_prompt=yes;;
esac

# uncomment for a colored prompt, if the terminal has the capability; turned
# off by default to not distract the user: the focus in a terminal window
# should be on the output of commands, not on the prompt
#force_color_prompt=yes

if [ -n "$force_color_prompt" ]; then
    if [ -x /usr/bin/tput ] && tput setaf 1 >&/dev/null; then
	# We have color support; assume it's compliant with Ecma-48
	# (ISO/IEC-6429). (Lack of such support is extremely rare, and such
	# a case would tend to support setf rather than setaf.)
	color_prompt=yes
    else
	color_prompt=
    fi
fi

if [ "$color_prompt" = yes ]; then
    PS1='${debian_chroot:+($debian_chroot)}\[\033[01;32m\]\u@\h\[\033[00m\]:\[\033[01;34m\]\w\[\033[00m\]\$ '
else
    PS1='${debian_chroot:+($debian_chroot)}\u@\h:\w\$ '
fi
unset color_prompt force_color_prompt

# If this is an xterm set the title to user@host:dir
case "$TERM" in
xterm*|rxvt*)
    PS1="\[\e]0;${debian_chroot:+($debian_chroot)}\u@\h: \w\a\]$PS1"
    ;;
*)
    ;;
esac

# enable color support of ls and also add handy aliases
if [ -x /usr/bin/dircolors ]; then
    test -r ~/.dircolors && eval "$(dircolors -b ~/.dircolors)" || eval "$(dircolors -b)"
    alias ls='ls --color=auto'
    #alias dir='dir --color=auto'
    #alias vdir='vdir --color=auto'

    alias grep='grep --color=auto'
    alias fgrep='fgrep --color=auto'
    alias egrep='egrep --color=auto'
fi

# colored GCC warnings and errors
#export GCC_COLORS='error=01;31:warning=01;35:note=01;36:caret=01;32:locus=01:quote=01'

# some more ls aliases
alias ll='ls -alF'
alias la='ls -A'
alias l='ls -CF'

# Add an "alert" alias for long running commands.  Use like so:
#   sleep 10; alert
alias alert='notify-send --urgency=low -i "$([ $? = 0 ] && echo terminal || echo error)" "$(history|tail -n1|sed -e '\''s/^\s*[0-9]\+\s*//;s/[;&|]\s*alert$//'\'')"'

# Alias definitions.
# You may want to put all your additions into a separate file like
# ~/.bash_aliases, instead of adding them here directly.
# See /usr/share/doc/bash-doc/examples in the bash-doc package.

if [ -f ~/.bash_aliases ]; then
    . ~/.bash_aliases
fi

# enable programmable completion features (you don't need to enable
# this, if it's already enabled in /etc/bash.bashrc and /etc/profile
# sources /etc/bash.bashrc).
if ! shopt -oq posix; then
  if [ -f /usr/share/bash-completion/bash_completion ]; then
    . /usr/share/bash-completion/bash_completion
  elif [ -f /etc/bash_completion ]; then
    . /etc/bash_completion
  fi
fi

cat .bash_logout

# ~/.bash_logout: executed by bash(1) when login shell exits.

# when leaving the console clear the screen to increase privacy

if [ "$SHLVL" = 1 ]; then
    [ -x /usr/bin/clear_console ] && /usr/bin/clear_console -q
fi