■ Introduction
I like to refresh my desktop layout from time to time and experiment
with different configurations. My usual workflow involves just a simple
Xlib/Xm based stacking wm, such as CTWM, Fvwm or Emwm.

Lately, I've been reconsiderig the idea of adding a status bar to my
ctwm desktop, to monitor a number of system resources which are relevant
on a laptop used to compile large programs.

■ Looking around 
I wanted something simple, ideally with little to none dependency
burden; eventually I came across @gonzalo's <termbar>, which is based 
on xterm and uses a looping sh script to display system's information on 
a docked horizontal terminal window.

Initially, I adapted termbar's functions to NetBSD, and while I got a
working status bar, I was unconvinced about xterm as a backend for the 
script, given the following reasons:

* impossibility to align text to the center / right side of the screen
  without complex and fragile printf hacks
* no way to set bar geometry at runtime based on screen size (xterm will
  only understand width in columns)
* no EWMH support
* tendency to print unwanted characters when output changes

I thought of <lemonbar> as a possible replacement for xterm, given its 
extreme lightweight and simplicity.

From lemonbar(1):

 "lemonbar (formerly known as bar) is a lightweight bar entirely based on
  XCB. Provides full UTF-8 support, basic formatting, RandR and Xinerama
  support and EWMH compliance without wasting your precious memory."

■ The status bar script  
After installing x11/lemonbar from pkgsrc, I made few modifications to
my status bar script to adapt it to lemonbar's screenrc like syntax;
here comes `bar' in its final version:

```
#!/bin/sh

# configuration
. $HOME/.barrc

# alpha
a="#cc"
b="#00"

# default colors
bg="${a}${BG}"
fg="${a}${FG}"
sp="${a}${C5}"
hi="${a}${C6}"

# default geometry
default_geometry() {
width=$(xdpyinfo | awk '/dimensions:/ { print $2}' | cut -c 1-4)
height=24
offy=0
offx=0

echo "${width}x${height}+${offx}+${offy}"
}

GEOM=${GEOM:-$(default_geometry)}

PATH="/bin:/sbin:/usr/bin:/usr/sbin:/usr/X11R7/bin:/usr/pkg/bin"

statusbar() {

desktop() {
	desk_id=$(xprop -root 32c '\t$0' _NET_CURRENT_DESKTOP | cut -f 2)
	w_id=$(xprop -root 32x '\t$0' _NET_ACTIVE_WINDOW | cut -f 2)
	win=$(xprop -id $w_id '\t$0' _NET_WM_NAME | awk -F '"' '{ print $2 }')
	echo [$desk_id] [$win]
}

host() {
	vendor="$(sysctl machdep.dmi.system-vendor | cut -d "= " -f2)"
	host="$(sysctl machdep.dmi.system-version | cut -d "= " -f2)"
	for i in $vendor $host; do
		[ -z "${i}" ] || echo $i
	done
}

cpu() {
	cpu_temp="$(envstat | grep "cpu0 temperature: " \
	| awk '{print $3}' | cut -d "." -f 1)°C"
	cpu_speed="$(printf "%4s" $(sysctl machdep.cpu.frequency.current \
	| awk '{ print $3 }' | cut -d "." -f 1)) MHz"
	echo $cpu_speed $cpu_temp
}

mem() {
	memtotal="$(($(sysctl -n hw.physmem64) / 1024 / 1024))"
	memused="$(($(vmstat | awk 'END {printf $3}') / 1024))"
	mem="${memused}MB / ${memtotal}MB"
	echo  $mem
}

disk() {
        disk="$(df -h / | awk 'NR==2 {total=$2; used=$3; \
		print used" / "total}')"
	echo $disk
}

network() {
	ifconfig | grep -v 127.0.0.1 | grep -q "inet " || {
		net=$(printf '%s' "none")
		exit 1
	}

	
for I in $( ifconfig -l | sed s/lo0//g )
	do
	ifconfig ${I} | grep -q "inet " && {
		net=$(printf '%s'  "(${I}) "
		ifconfig ${I} | grep "inet " | awk '{print $2}' | tr '\n' ' ')
	echo $net
	}
done
}

batt() {
	batt="$(envstat | grep charge: | sed 's/.*(\(.*\))/\1/' | head -1)"

	
if envstat | grep -Eq 'connected.*TRUE'; then
		batt_status=$(echo Connected)
	else
		batt_status=$(echo Disconnected)
        fi

	
echo $batt "($batt_status)"
}

vol() {
	vol="$(mixerctl -n outputs.master | tr ',' ' ' \
	| awk '{print ($1+$2)/5}')%"
	echo $vol
}

clock() {
	time="$(date +"%I:%M %p")"
	date="$(date +" %a, %b %d")"
#	datetime=$(date '+%d/%m/%Y [%H:%M]')
	echo  $date "@" $time
}

echo %{l}%{F${hi}}$(host) %{F-}%{F${fg}}$(desktop)%{F-}%{c}%{F-}%{r}%{F${sp}}" \
	| "%{F-}%{F${fg}}cpu: $(cpu)%{F-}%{F${sp}}" \
	| "%{F-}%{F${fg}}mem: $(mem)%{F-}%{F${sp}}" \
	| "%{F-}%{F${fg}}net: $(network)%{F-}%{F${sp}}" \
	| "%{F-}%{F${fg}}disk: $(disk)%{F-}%{F${sp}}" \
	| "%{F-}%{F${fg}}batt: $(batt)%{F-}%{F${sp}}" \
	| "%{F-}%{F${fg}}vol: $(vol) %{F-}%{F${sp}}" \
	| "%{F-}%{F${fg}}$(clock)%{F-}%{F${sp}}" "%{F-}
}

while true
 do
   echo "$(statusbar)"
   sleep 1.0

 done |  lemonbar -d -n $NAME -g $GEOM -f $FONT -B $bg
```

The script launches a status bar at the top of the screen displaying the
following information (from left to right):

- host (vendor and model)
- number of current desktop/workspace
- title of focused window
- cpu frequency and temperature
- used memory (out of total)
- connected network interface(s) and associated address
- used and total disk space
- battery charge level and status (connected or not to power supply)
- volume level
- date and time

■ The status bar resources 
The script sources a `barrc' configuration file (required), containing
customizable colors and font respources. An example is provided below: 

```
#!/bin/sh

FG=D8D8D8
BG=272c2d
C0=000000
C1=9e1828
C2=aece92
C3=968a38
C4=414171
C5=963c59
C6=418179
C7=bebebe

NAME="bar"
FONT="-misc-tamzen-medium-r-normal--16-116-100-100-c-80-iso8859-1"

export FG BG C0 C1 C2 C3 C4 C5 C6 C7 NAME FONT
```

This should be placed by default at ~/.barrc.
The bar script and its configuration file can be downloaded from <https://sehnsucht.multics.org/dots/lemonbar>.

■ Let ctwm(1) know about the bar
We want the status bar to:
- have no decorations whatsoever
- occupy all workspaces permanently
- stay beneath focused and unfocused windows
- not appear in IconManager and WorkspaceManager
- be excluded from the window ring (when cycling through windows)

This can be achieved in ~/.ctwmrc by adding it to series of window
lists:

```
NoTitle
{   
    "WorkSpaceManager"
    "TWM Icon Manager"
    "XClock"
    "bar"
}

NoBorder
{
    "WorkSpaceManager"
    "TWM Icon Manager"
    "bar"
}

IconManagerDontShow
{
    "WorkSpaceManager"
    "bar"
}

OccupyAll 
{
    "XClock"
    "xsm"
    "xconsole"
    "bar"
}

WindowRingExclude
{
    "TWM Icon Manager"
    "WorkSpaceManager"
    "XClock"
    "xsm"
    "xconsole"
    "bar"
}

AutoLower
{
    "TWM Icon Manager" 
    "WorkSpaceManager"
    "XClock"
    "xsm"
    "xconsole"
    "bar"
}

■ Start it automatically 
The bar script may be executed directly from ~/.xsession:

```
# [...]

# Launch status bar
sleep 1; ${HOME}/bin/bar &

# Start CTWM 
exec /usr/pkg/bin/dbus-launch --exit-with-session \
	--sh-syntax /usr/X11R7/bin/ctwm -W
```

Or you may have CTWM execute it upon startup, by adding:

```
# launch bar 
syscmd(`sh $HOME/bin/bar  > /dev/null 2>&1')

```

To ~/.ctwmrc. 




■ Thanks
* gonzalo (@x61sh) for having heavily inspired this work.  
* TuM'Fatig for their exhaustive review on termbar. See:
  <https://www.tumfatig.net/2020/a-simple-shell-status-bar-for-openbsd-and-cwm1/> 

■ TODO
* Rewrite it in C, possibly starting from <https://got.x61.sh/?action=summary&path=termbarc>