lemonbar
a minimalistic (windowmanager) panel

1.1.1. First script

#!/bin/bash

while true; do
  echo "%{c}%{B#770}%{F#000}Hello world"
  sleep 1
done

./test.sh | lemonbar

1.1.2. More advanced scripts

clock() {
        DATETIME=$(date "+%a %d.%b %T")

        echo -n "$DATETIME"
}
while true; do

    buf="%{l}%{B#000}%{F#FFF} $(clock) "
# a commented out centered clock
#    buf="%{c}%{B#000}%{F#FFF} $(clock) "
    buf="${buf} %{c}Hello World!"
      echo $buf
      sleep 1
done;

1. Battery Status
   

   A simple function to diplay the battey percentage might look like this:

   Battery() {
           BATPERC=$(acpi --battery | cut -d, -f2)
           echo "$BATPERC"
   }
   

   Which outputs the percentage like 96%. I like to have it on the right side of my panel, so I'd go like this:

   buf="${buf}%{r}$(Battery)"
   

   But then, I thought I'd like to see if the battery charges or looses power, or if the powersupply is plugged in. That's when I came up with something like:

   battery() {
       BATC=/sys/class/power_supply/BAT0/capacity
       BATS=/sys/class/power_supply/BAT0/status
       AC=$(acpi --ac-adapter | cut -d: -f2)
   
       if [[ $AC == *"on-line"* ]]; then
         test "`cat $BATS`" = "Charging" && echo -n '+' || echo -n '~';
       else
         test "`cat $BATS`" = "Charging" && echo -n '+' || echo -n '-';
       fi
       sed -n p $BATC
   }
   

   …and added it to the buffer ($buf) like that:

   buf="${buf} %{F#02C}BAT: %{F#FFF}$(battery)"
   

2. Windows and Desktops
   

   Since using bspwm and sxhkd most of my windows are displayed fullscreen, I use multiple dektops and switch alot between them. That's why knowing the dektops I am on and displaying the name is important to me. For this reason I have two little funtions to help me out:

   # get and echo the current dektop name
   desktopname() {
       cur=`xprop -root _NET_CURRENT_DESKTOP | awk '{print $3}'`
       desktop_names=`xprop -root _NET_DESKTOP_NAMES`
       cur_name_id=`bc <<< $cur+2+$cur`
       cur_name=`echo ${desktop_names} | awk -v var="$cur_name_id" -F "\"" '{print $var}'`
       echo $cur_name
   }
   

   Let's go through step by step:

   xprop -root _NET_CURRENT_DESKTOP | awk '{print $3}' prints out the current dektop number.

   xprop -root _NET_DESKTOP_NAMES returns a list of desktop names like this:

   _NET_DESKTOP_NAMES(UTF8_STRING) = "bash", "mail", "firefox", "zeug", "stuff", "jack", "gimp", "morestuff", "Desktop"

   Then these infos given the next line calculates the id for awk (next line) then outputs the current Desktop name in the end :) I use it like this inside the panel:

   buf="${buf} «« $(desktopname) »»"
   

   The next one is an dynamic and graphic way to display the current dektop number:

   # get all dektops and display them while highlighting the current one
   groups() {
       cur=`xprop -root _NET_CURRENT_DESKTOP | awk '{print $3}'`
       tot=`xprop -root _NET_NUMBER_OF_DESKTOPS | awk '{print $3}'`
       window=`bc <<< $cur+1`
       desktop_names=`xprop -root _NET_DESKTOP_NAMES`
       cur_name_id=`bc <<< $cur+2+$cur`
       cur_name=`echo ${desktop_names} | awk -v var="$cur_name_id" -F "\"" '{print $var}'`
       for w in `seq 0 $((cur - 1))`;do line="${line}%{B#000}%{F#888}="; done
       line="${line}%{B#FFF}%{F#000} $window %{F#000}"
       for w in `seq $((cur + 2)) $tot`; do line="${line}%{B#000}%{F#888}="; done
       echo $line
   }
   

   Based on the two infos _NET_CURRENT_DESKTOP and _NET_NUMBER_OF_DEKTOPS we create a little loop to highlight the current dektop and display the other ones as = and unhighlighted. We add it to our buffer:

   buf="${buf} %{c}»»[$(groups)%{B#000}%{F#FFF}]««"
   

   And it should finally look like this (if you're on dektop 4):

   

   Figure 1: A screenshot from my lemonbar

3. Volume, CPU, RAM
   

   To show my CPU usage or my used RAM I use the following two functions:

   cpuload() {
       LINE=`ps -eo pcpu |grep -vE '^\s*(0.0|%CPU)' |sed -n '1h;$!H;$g;s/\n/ +/gp'`
       X=`bc <<< $LINE`
       bc <<< $X/4
   }
   
   memused() {
       t=`grep -E 'Mem(Total)' /proc/meminfo |awk '{print $2}'`
       f=`grep -E 'Mem(Free)' /proc/meminfo |awk '{print $2}'`
       bc <<< "scale=2; 100 - $f / $t * 100" | cut -d. -f1
   }
   

   The first one grabbing the CPU percentage with ps -eo pcpu, then adding the values and dividing the result by 8 (because of my eight cores). This gives me the aproximate load in percentage :) I add it to the buffer like this:

   buf="${buf} %{F#C20}CPU: %{F#FFF}$(cpuload)"
   buf="${buf} %{F#C20}RAM: %{F#FFF}$(memused)"
   

   I need to adjust the colors to the load.. something like from green (low load) to yellow, then red (heavy load). But that's still in progress :D

   To display the current volume I use amixer like that:

   volume() {
       amixer get Master | sed -n 's/^.*\[\([0-9]\+\)%.*$/\1/p'| uniq
   }
   

   …and fill the buffer like this:

   buf="${buf} %{F#090}VOL: %{F#FFF}$(volume)"
   

4. Network stuff
   

   To display my network status, like "is my device connected to any WLAN?" and "what external IP do we have here?". In order to get the network connection state I use this function:

   network() {
       wifi='wlo1'
         # I once used it to detect ethernet connections with:
       # eth0='enp0s31f6'
   
       ip link show $wifi | grep 'state UP' >/dev/null && int=$wifi
   
       # in case of ethernet this last thing would be: ... && int=eth0
   
       ping -c 1 bios-blog.com >/dev/null 2>&1 &&
           echo "$int connected" || echo "$int disconnected"
   }
   

   This simply shows the connection state of my wireless network device. To display my external IP I have a simple webservice running which responses with the IP calling the site. So I can go with curl like that:

   get_ip() {
       curl -s my.webservice.com | grep '<p></p>' | awk -F "<p></p>" '{print $1}' | awk -F " " '{print $1}'
   }
   

   I kinda like sort the IP out from the stuff written on the website with the grep and awk commands. :) In the end I append this to my buf variable like that:

   buf="${buf} %{r}%{F#990}NET: %{F#FFF}$(network)"
   

   The %{r} is only to display this on the right side of my bar…