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Goal: Show the Herbstclient Tag.

Focusing in "herbstclient tag_status". 

HerbstluftWM: Tag Status

This tutorial cover Lemonbar, and in order to use Dzen2, any reader could use the source code in github.


Before you jump off to scripting, you might desire to read this overview.

All The Source Code:

Impatient coder like me, like to open many tab on browser.

HerbstluftWM Tag Status in Many Languages

This article is one part of a collection. All integrated, one related to another. So we can compare each other quickly.

Tutorial/ Guidance/ Article: [ Tag Status Overview ] [ BASH ] [ Perl ] [ Python ] [ Ruby ] [ PHP ] [ Lua ] [ Haskell ]

Dzen2 Source Code Directory: [ BASH ] [ Perl ] [ Python ] [ Ruby ] [ PHP ] [ Lua ] [ Haskell ]

Lemonbar Source Code Directory: [ BASH ] [ Perl ] [ Python ] [ Ruby ] [ PHP ] [ Lua ] [ Haskell ]


Since window manager is out of topic in this tutorial, I present only panel HerbstluftWM screenshot.


Statusbar: Dzen2 Screenshot


Statusbar: Lemonbar Screenshot

Directory Structure

Directory Structure has been explained in preface. For both Dzen2 and Lemonbar, the structure are the same. This figure will explain how it looks in Perl script directory.

Statusbar: Directory Structure

Special customization can be done in output script, without changing the whole stuff.

Get Geometry

Let’s have a look at helper.pm in github.

View Source File:

Get Script Argument

The original herbstluftwm panel example, contain statusbar for each monitor. The default is using monitor 0, although you can use other monitor as well.

$ ./panel.pm 0

I do not implement statusbar in multi monitor since I only have my notebook. But I’ll pass the argument anyway for learning purpose. Here it is our code in Perl.


# script arguments
sub get_monitor {
    my @arguments = @_; 
    my $num_args  = $#arguments;
    # ternary operator
    my $monitor = ($num_args > 0) ? $arguments[0] : 0;
    return $monitor;

And in main code we can call

use File::Basename;
use lib dirname(__FILE__);
use helper;

my $monitor = helper::get_monitor(@ARGV);
print $monitor."\n";

This will display 0 or else such as 1, depend on the script argument given.


Get Monitor Geometry

HerbstluftWM give this little tools to manage monitor geometry by getting monitor rectangle.

$ herbstclient monitor_rect

This will show something similar to this.

0 0 1280 800

HerbstluftWM: Monitor Rectangle

Consider wrap the code into function. And get an array as function return.


sub get_geometry {
    my $monitor = shift;

    my $geometry_qx = qx(herbstclient monitor_rect "$monitor");
    if ($geometry_qx eq "") { 
        print "Invalid monitor $monitor\n";
        exit 1
    my @geometry = split / /, $geometry_qx;
    return @geometry;

Consider call this function from script later. To print array in Perl, we just have to wrap it in "@geometry".

my $panel_height = 24;
my $monitor  = helper::get_monitor(@ARGV);
my @geometry = helper::get_geometry($monitor);
print "@geometry";

This will produce

0 0 1280 800

Get Panel Geometry

The Panel geometry is completely depend on the user flavor and taste. You can put it, on top, or bottom, or hanging somewhere. You can create gap on both left and right.

Consider this example: helper.pm

sub get_bottom_panel_geometry {
    my $height = shift;
    my @geometry = @_;

    # geometry has the format X Y W H
    return ($geometry[0] + 24, $geometry[3] - $height, 
            $geometry[2] - 48, $height);

We are going to use this X Y W H, to get lemonbar parameter.

my $panel_height = 24;
my $monitor  = helper::get_monitor(@ARGV);
my @geometry = helper::get_geometry($monitor);
my ($xpos, $ypos, $width, $height) = 
        helper::get_bottom_panel_geometry($panel_height, @geometry);

print "Lemonbar geometry: ${width}x${height}+${xpos}+${ypos}\n";

This will show something similar to this result, depend on your monitor size.

Lemonbar geometry: 1280x24+24+776

Get Lemonbar Parameters

We almost done. This is the last step. We wrap it all inside this function below.


sub get_lemon_parameters {   
    # parameter: function argument
    my $monitor = shift;
    my $panel_height = shift;

    # calculate geometry
    my @geometry = get_geometry($monitor);
    my ($xpos, $ypos, $width, $height) = 
       get_top_panel_geometry($panel_height, @geometry); 

    # geometry: -g widthxheight+x+y
    my $geom_res = "${width}x${height}+${xpos}+${ypos}";
    # color, with transparency
    my $bgcolor = '#aa000000';
    my $fgcolor = '#ffffff';
    # XFT: require lemonbar_xft_git 
    my $font_takaop  = "takaopgothic-9";
    my $font_bottom  = "monospace-9";
    my $font_symbol  = "PowerlineSymbols-11";
    my $font_awesome = "FontAwesome-9";

    # finally
    my $parameters = "  -g $geom_res -u 2"
                   . " -B $bgcolor -F $fgcolor"
                   . " -f $font_takaop -f $font_awesome -f $font_symbol";

    return $parameters;

Testing The Parameters

Consider this code 01-testparams.pl. The script call the above function to get lemon parameters.


use warnings;
use strict;

use File::Basename;
use lib dirname(__FILE__);

use helper;

# initialize
my $panel_height = 24;
my $monitor = helper::get_monitor(@ARGV);

my $lemon_parameters = helper::get_lemon_parameters(
    $monitor, $panel_height);

print $lemon_parameters."\n";

This will produce output something similar to this result

-g 1280x24+0+0 -u 2 -B #aa000000 -F #ffffff 
-f takaopgothic-9 -f FontAwesome-9 -f PowerlineSymbols-11

Or in Dzen2 version:

-x 0 -y 0 -w 1280 -h 24 -ta l 
-bg '#000000' -fg '#ffffff' -title-name dzentop 
-fn '-*-takaopgothic-medium-*-*-*-12-*-*-*-*-*-*-*'

View Source File:

Adjusting the Desktop

Since we want to use panel, we have to adjust the desktop gap, giving space at the top and bottom.

$ herbstclient pad 0 24 0 24 0

For more information, do $ man herbsluftclient, and type \pad to search what it means.

In script, it looks like this below.

system("herbstclient pad $monitor $panel_height 0 $panel_height 0");

Color Schemes

Using a simple data structure key-value pairs, we have access to google material color for use with dzen2 or lemonbar. Having a nice pallete to work with, makes our panel more fun.


our %color = (
    'white' => '#ffffff',
    'black' => '#000000',

    'grey50'  => '#fafafa',
    'grey100' => '#f5f5f5'

View Source File:

Preparing Output

Let’s have a look at output.pm in github.

View Source File:

Global Variable and Constant

There are a several ways to define constant in Perl. Constant in Perl may begin with the word use const.

Mutable State: Segment Variable

The different between interval based and event based is that, with interval based all panel segment are recalculated, while with event based only recalculate the trigerred segment.

In this case, we only have two segment in panel.

  • Tag

  • Title

output.pm In script, we initialize the variable as below

my $segment_windowtitle = ''; # empty string
my @tags_status = [];         # empty array

Each segment buffered. And will be called while rendering the panel.

Global Constant: Tag Name

Assuming that herbstclient tag status only consist of nine number element.

$ herbstclient tag_status
	#1	:2	:3	:4	:5	.6	.7	.8	.9	

We can manage custom tag names, consist of nine string element. We can also freely using unicode string instead of plain one.


use constant TAG_SHOWS => ['一 ichi', '二 ni', '三 san', '四 shi', 
    '五 go', '六 roku', '七 shichi', '八 hachi', '九 kyū', '十 jū'];

Global Constant: Decoration

output.pm Decoration consist lemonbar formatting tag.

use gmc;

# decoration
use constant SEPARATOR => "%{B-}%{F$color{'yellow500'}}|%{B-}%{F-}";

# Powerline Symbol
use constant RIGHT_HARD_ARROW => "";
use constant RIGHT_SOFT_ARROW => "";
use constant LEFT_HARD_ARROW  => "";
use constant LEFT_SOFT_ARROW  => "";

# theme
use constant PRE_ICON  => "%{F$color{'yellow500'}}";
use constant POST_ICON => "%{F-}";

Segment Variable

As response to herbstclient event idle, these two function set the state of segment variable.


sub set_tag_value {
    my $monitor = shift;
    my $tag_status_qx = qx(herbstclient tag_status $monitor);
       $tag_status_qx =~ s/^\s+|\s+$//g;
    @tags_status = split(/\t/, $tag_status_qx);

This function above turn the tag status string into array of tags for later use.


sub set_windowtitle {
    my $windowtitle = shift;  
    my $icon = PRE_ICON."".POST_ICON;
    $segment_windowtitle = " $icon "
                         . "%{B-}%{F$color{'grey700'}} $windowtitle";

We will call these two functions later.

Decorating: Window Title

This is self explanatory. I put separator, just in case you want to add other segment. And then returning string as result.


sub output_by_title {
    my $text = "$segment_windowtitle ".SEPARATOR."  ";

    return $text;

Decorating: Tag Status

This transform each plain tag such as .2, to decorated tag names such as 二 ni. Note that it only process one tag. We process all tags in a loop in other function.

This has some parts:

  • Pre Text: Color setting for Main Text (Background, Foreground, Underline). Arrow before the text, only for active tag.

  • Main Text: Tag Name by number, each with their tag state #, +, ., |, !, and each tag has clickable area setting.

  • Post Text: Arrow after the text, only for active tag.

  • Color Reset: %{B-}, %{F-}, %{-u} (Background, Foreground, Underline).


sub output_by_tag {
    my $monitor = shift;    
    my $tag_status = shift;
    my $tag_index  = substr($tag_status, 1, 1);
    my $tag_mark   = substr($tag_status, 0, 1);
    my $tag_name   = TAG_SHOWS->[$tag_index - 1]; # zero based

    # ----- pre tag

    my $text_pre = '';
    if ($tag_mark eq '#') {
        $text_pre = "%{B$color{'blue500'}}%{F$color{'black'}}"
                  . "%{U$color{'white'}}%{+u}".RIGHT_HARD_ARROW
                  . "%{B$color{'blue500'}}%{F$color{'white'}}"
                  . "%{U$color{'white'}}%{+u}";
    } elsif ($tag_mark eq '+') {
        $text_pre = "%{B$color{'yellow500'}}%{F$color{'grey400'}}";
    } elsif ($tag_mark eq ':') {
        $text_pre = "%{B-}%{F$color{'white'}}"
                  . "%{U$color{'red500'}}%{+u}";
    } elsif ($tag_mark eq '!') {
        $text_pre = "%{B$color{'red500'}}%{F$color{'white'}}"
                  . "%{U$color{'white'}}%{+u}";
    } else {
        $text_pre = "%{B-}%{F$color{'grey600'}}%{-u}";

    # ----- tag by number

    # clickable tags
    my $text_name = "%{A:herbstclient focus_monitor \"$monitor\" && "
                  . "herbstclient use \"$tag_index\":} $tag_name %{A} ";
    # non clickable tags
    # my $text_name = " $tag_name ";

    # ----- post tag
    my $text_post = "";
    if ($tag_mark eq '#') {
        $text_post = "%{B-}%{F$color{'blue500'}}"
                   . "%{U$color{'red500'}}%{+u}"
                   . RIGHT_HARD_ARROW;
    my $text_clear = '%{B-}%{F-}%{-u}';
    return $text_pre . $text_name . $text_post . $text_clear;

Combine The Segments

Now it is time to combine all segments to compose one panel. Lemonbar is using %{l} to align left segment, and %{r} to align right segment. All tags processed in a loop.


sub get_statusbar_text {
    my $monitor = shift;   
    my $text = '';

    # draw tags
    $text .= '%{l}';
    foreach my $tag_status (@tags_status) {
        $text .= output_by_tag($monitor, $tag_status);
    # draw window title
    $text .= '%{r}';
    $text .= output_by_title();
    return $text;

Testing The Output

Consider this code 02-testoutput.pl. The script using pipe as feed to lemonbar.

We append -p parameter to make the panel persistent.


use warnings;
use strict;

use File::Basename;
use lib dirname(__FILE__);

use helper;

# process handler
sub test_lemon { 
    use IO::Pipe;
    use output;

    my $monitor = shift;
    my $parameters = shift;
    my $pipe_out = IO::Pipe->new();
    my $command = "lemonbar $parameters -p";
    my $handle = $pipe_out->writer($command);

    # initialize statusbar

    my $text = output::get_statusbar_text($monitor);
    print $pipe_out $text."\n";
    flush $pipe_out;


# initialize
my $panel_height = 24;
my $monitor = helper::get_monitor(@ARGV);
my $lemon_parameters = helper::get_lemon_parameters(
    $monitor, $panel_height);

# test
system("herbstclient pad $monitor $panel_height 0 $panel_height 0");
test_lemon($monitor, $lemon_parameters);

This will produce a panel on top.

Statusbar: Lemonbar Screenshot

The panel only contain the initialized version of the text. It does not really interact with the HerbstluftWM event.

You can also click the clickable area to see it’s result. It only show text, not executed yet.

herbstclient focus_monitor "0" && herbstclient use "2"
herbstclient focus_monitor "0" && herbstclient use "3"

View Source File:

Coming up Next

It is already a long tutorial. It is time to take a break for a while.

We are going to continue on next tutorial to cover interaction between the script process and HerbstluftWM idle event.

Enjoy the statusbar !