Desktop start script for conky

#!/bin/sh
############################################################ IDENT(1)
#
# $Title: Script for starting conky and initializing random desktop $
#
############################################################ CONFIGURATION

#nohup /bin/sh -c 'dbus-monitor > monitor.$$.log 2>&1' &

#
# Conky configuration file
#
CONKY_CONFIG=theme/conky/ident.conkyrc
CONKY_GNOME_CONFIG=theme/conky/ident-gnome-vmware.conkyrc
CONKY_KDE_CONFIG=theme/conky/ident-kde-vmware.conkyrc

#
# Where to find wallpaper
# NB: Relative paths are in home directory
#
WALLPAPER=Wallpaper

#
# How often (in seconds) to rotate the desktop
# NB: Rotation is to a random image in WALLPAPER directory
# MB: Should be divisible by DESKTOP_TIMEOUT
#
DESKTOP_INTERVAL=600 # 10 minutes
DESKTOP_TIMEOUT=10 # seconds

#
# Wait for DBus registry elements
# NB: Any one will trigger start or timeout
#
DBUS_TIMEOUT=60
DBUS_GNOME=org.gnome.SessionManager
DBUS_KDE=org.kde.kuiserver
DBUS_WAIT_FOR="
    $DBUS_GNOME
    $DBUS_KDE
" # END-QUOTE

############################################################ MAIN

cd # Home directory

#
# Short-hand
#
DBUS_LISTNAMES=$( echo dbus-send \
    --session           \
    --dest=org.freedesktop.DBus \
    --type=method_call      \
    --print-reply           \
    /org/freedesktop/DBus       \
    org.freedesktop.DBus.ListNames
)
DBUS_GNOME_RE='\<'"$( echo "$DBUS_GNOME" | awk 'gsub(/\./, "\\.")||1' )"'\>'
DBUS_KDE_RE='\<'"$( echo "$DBUS_KDE" | awk 'gsub(/\./, "\\.")||1' )"'\>'
DBUS_WAIT_RE='\<\('"$( echo "$DBUS_WAIT_FOR" | xargs -n 1 | awk '
    {
        re = $0
        gsub(/\./, "\\.", re)
        buf = buf "\\|" re
    }
    END { print substr(buf, 3) }
' )"'\)\>'

#
# Start conky
#
pkill -f conky > /dev/null 2>&1
sleep 1
nohup /bin/sh -c "
    countup=0
    names=
    while : forever ; do
        names=\$( $DBUS_LISTNAMES )
        echo \"\$names\" | grep -q '$DBUS_WAIT_RE' && break
        [ \$countup -gt $DBUS_TIMEOUT ] && break
        sleep 5
        countup=\$(( \$countup + 5 ))
    done
    if echo \"\$names\" | grep -q '$DBUS_GNOME_RE'; then
        config=\"$CONKY_GNOME_CONFIG\"
    elif echo \"\$names\" | grep -q '$DBUS_KDE_RE'; then
        config=\"$CONKY_KDE_CONFIG\"
    else
        config=\"$CONKY_CONFIG\"
    fi
    nohup conky -c \"\$config\" > /dev/null 2>&1 &
" > /dev/null 2>&1 &

#
# Start desktop worker
# NB: Rotates Wallpaper every $DESKTOP_INTERVAL seconds
#
export WALLPAPER
exec 9<<'EOF'
set -e # errexit
wallpapers=$( find $WALLPAPER -mindepth 1 -maxdepth 1 -type f | sort )
nwallpapers=$( echo "$wallpapers" | awk 'END{print NR}' )
n=$( awk -v max=$nwallpapers 'BEGIN {
    srand()
    srand(srand())
    r = sprintf("%0.f", rand() * max)
    print (r > 0 ? r : 1)
}' )
wallpaper=$( echo "$wallpapers" | awk -v n=$n 'NR==n' )
[ "$wallpaper" ] && hsetroot -fill "$wallpaper"
EOF
DESKTOP_WORKER=$( cat <&9 )
export DESKTOP_WORKER
nohup /bin/sh -ec "
    countdown=0
    countup=0
    while ! $DBUS_LISTNAMES | grep -q '$DBUS_WAIT_RE'; do
        [ \$countup -gt $DBUS_TIMEOUT ] && break
        sleep 5
        countup=\$(( \$countup + 5 ))
    done
    while pgrep -q conky; do
        if [ \$countdown -le 0 ]; then
            eval \"\$DESKTOP_WORKER\"
            countdown=$DESKTOP_INTERVAL
        else
            sleep $DESKTOP_TIMEOUT
            countdown=\$(( \$countdown - $DESKTOP_TIMEOUT ))
        fi
    done
" > /dev/null 2>&1 &

################################################################################
# END
################################################################################