Xmobar - A Minimalistic Text Based Status Bar

About
Download
Installation
Configuration
Plugins
- Writing a Plugin
- Installing/Removing a Plugin
Credits
Useful links
Author
Legal

About

Xmobar is a minimalistic, text based, status bar. It was designed to work with the XMonad Window Manager.

It was inspired by the Ion3 status bar, and supports similar features, like dynamic color management, output templates, and extensibility through plugins.

This is a screen shot of my desktop with XMonad and Xmobar.

See xmobar.config-sample, distributed with the source code, for a sample configuration.

Download

You can get the Xmobar source code from Hackage.

To get the darcs source run:

    darcs get http://code.haskell.org/xmobar/

The latest binary can be found here:

    http://code.haskell.org/~arossato/xmobar/xmobar-0.8.bin

A recent screen shot can be found here:

    http://code.haskell.org/~arossato/xmobar/xmobar-0.8.png

Version 0.8 requires Cabal-1.2.x, but works both with ghc-6.6.1 and ghc-6.8.1.

Here you can find a source tree of xmobar-0.8 which works with Cabal-1.1.x, but compiles only with ghc-6.6.x:

    http://code.haskell.org/~arossato/xmobar/xmobar-0.8-Cabal-1.1-ghc-6.6.tar.gz

Installation

To install simply run:

    tar xvfz xmobar-0.8
    cd xmobar-0.8
    runhaskell Setup.lhs configure --prefix=/usr/local
    runhaskell Setup.lhs build
    runhaskell Setup.lhs haddock --executables # optional
    runhaskell Setup.lhs install # possibly to be run as root

Run with:

    xmobar /path/to/config &

    xmobar &

if you have the default configuration file saved as ~/.xmobarrc

Configuration

Quick Start

See xmobar.config-sample for an example.

For the output template:

%command% will execute command and print the output. The output may contain markups to change the characters' color.
<fc=#FF0000>string</fc> will print string with #FF0000 color (red).

Other configuration options:

font

Name of the font to be used

bgColor

Background color

fgColor

Default font color

position

Top, TopW, Bottom, BottomW or Static (with x, y, width and height).

TopW and BottomW take 2 arguments: an alignment parameter (L for left, C for centered, R for Right) and an integer for the percentage width Xmobar window will have in respect to the screen width

For example:

   position = Bottom C 75

to place Xmobar at the bottom, centered with the 75% of the screen width.

   position = Static { xpos = 0 , ypos = 0, width = 1024, height = 15 }

  position = Top

commands

For setting the options of the programs to run (optional)

sepChar

The character to be used for indicating commands in the output template (default '%')

alignSep

a 2 character string for aligning text in the output template. The text before the first character will be align to left, the text in between the 2 characters will be centered, and the text after the second character will be align to the right.

template

The output template

Command Line Options

Xmobar can be either configured with a configuration file or with command line options. In the second case, the command line options will overwrite the corresponding options set in the configuration file.

Example:

xmobar -B white -a right -F blue -t '%LIPB%' -c '[Run Weather "LIPB" [] 36000]'

This is the list of command line options (the output of xmobar --help):

Usage: xmobar [OPTION...] [FILE]
Options:
  -h, -?        --help               This help
  -V            --version            Show version information
  -f font name  --font=font name     The font name
  -B bg color   --bgcolor=bg color   The background color. Default black
  -F fg color   --fgcolor=fg color   The foreground color. Default grey
  -o            --top                Place Xmobar at the top of the screen
  -b            --bottom             Place Xmobar at the bottom of the screen
  -a alignsep   --alignsep=alignsep  Separators for left, center and right text
                                     alignment. Default: '}{'
  -s char       --sepchar=char       The character used to separate commands in
                                     the output template. Default '%'
  -t tempate    --template=tempate   The output template
  -c commands   --commands=commands  The list of commands to be executed
Mail bug reports and suggestions to <andrea.rossato@unibz.it>

The Output Template

The output template must contain at least one command. Xmobar will parse the template and will search for the command to be executed in the commands configuration option. First an alias will be searched (plugins such as Weather or Network have default aliases, see below). After that, the command name will be tried. If a command is found, the arguments specified in the commands list will be used.

If no command is found in the commands list, Xmobar will ask the operating system to execute a program with the name found in the template. If the execution is not successful an error will be reported.

The `commands` Configuration Option

The commands configuration option is a list of commands information and arguments to be used by Xmobar when parsing the output template. Each member of the list consists in a command prefixed by the Run keyword. Each command has arguments to control the way Xmobar is going to execute it.

The option consists in a list of commands separated by a comma and enclosed by square parenthesis.

Example:

[Run Memory ["-t","Mem: <usedratio>%"] 10, Run Swap [] 10]

to run the Memory monitor plugin with the specified template, and the swap monitor plugin, with default options, every second.

The only internal available command is Com (see below Executing External Commands). All other commands are provided by plugins. Xmobar comes with some plugins, providing a set of system monitors, a standard input reader, an Unix named pipe reader, and a configurable date plugin. These plugins install the following internal commands: Weather, Network, Memory, Swap, Cpu, Battery, Date, StdinReader, and PipeReader.

To remove them see below Installing/Removing a Plugin

Other commands can be created as plugins with the Plugin infrastructure. See below Writing a Plugin

System Monitor Plugins

This is the description of the system monitor plugins that are installed by default.

Each monitor has an alias to be used in the output template. Monitors have default aliases.

Weather StationID Args RefreshRate

aliases to the Station ID: so Weather "LIPB" [] can be used in template as %LIBP%
Args: the argument list (see below)
Variables that can be used with the -t/--template argument: station, stationState, year, month, day, hour, wind, visibility, skyCondition, tempC, tempF, dewPoint, rh, pressure
Default template: <station>: <tempC>C, rh <rh>% (<hour>)

Network Interface Args RefreshRate

aliases to the interface name: so Network "eth0" [] can be used as %eth0%
Args: the argument list (see below)
Variables that can be used with the -t/--template argument: dev, rx, tx
Default template: <dev>: <rx>|<tx>

Memory Args RefreshRate

aliases to memory
Args: the argument list (see below)
Variables that can be used with the -t/--template argument: total, free, buffer, cache, rest, used, usedratio
Default template: Mem: <usedratio>% (<cache>M)

Swap Args RefreshRate

aliases to swap
Args: the argument list (see below)
Variables that can be used with the -t/--template argument: total, used, free, usedratio
Default template: Swap: <usedratio>%

Cpu Args RefreshRate

aliases to cpu
Args: the argument list (see below)
Variables that can be used with the -t/--template argument: total, user, nice, system, idle
Default template: Cpu: <total>

Battery Args RefreshRate

aliases to battery
Args: the argument list (see below)
Variables that can be used with the -t/--template argument: left
Default template: Batt: <left>

Monitor Plugins Commands Arguments

These are the arguments that can be used for internal commands in the commands configuration option:

-H number           --High=number               The high threshold
-L number           --Low=number                The low threshold
-h color number     --high=color number         Color for the high threshold: es "#FF0000"
-n color number     --normal=color number       Color for the normal threshold: es "#00FF00"
-l color number     --low=color number          Color for the low threshold: es "#0000FF"
-t output template  --template=output template  Output template of the command.

Commands' arguments must be set as a list. Es:

Run Weather "EGPF" ["-t","<station>: <tempC>C"] 36000

In this case Xmobar will run the weather monitor, getting information for the weather station ID EGPF (Glasgow Airport, as a homage to GHC) every hour (36000 tenth of seconds), with a template that will output something like:

Glasgow Airport: 16.0C

Executing External Commands

In order to execute an external command you can either write the command name in the template, in this case it will be executed without arguments, or you can configure it in the "commands" configuration option list with the Com template command:

Com ProgarmName Args Alias RefreshRate

ProgramName: the name of the program
Args: the arguments to be passed to the program at execution time
Alias: a name to be used in the template. If the alias is en empty string the program name can be used in the template.

Es:

    Run Com "uname" ["-s","-r"] "" 36000

can be used in the output template as %uname%

    Run Com "date" ["+\"%a %b %_d %H:%M\""] "mydate" 600

can be used in the output template as %mydate%

Other Plugins

Date Args Alias RefreshRate

StdinReader

PipeReader "/path/to/pipe" Alias

Plugins

Writing a Plugin

Writing a plugin for Xmobar should be very simple. You need to create a data type with at least one constructor.

Next you must declare this data type an instance of the Exec class, by defining the 1 needed method (alternatively start or run) and 2 optional ones (alias and rate):

    start :: e -> (String -> IO ()) -> IO ()
    run   :: e -> IO String
    rate  :: e -> Int
    alias :: e -> String

start must receive a callback to be used to display the String produced by the plugin. This method can be used for plugins that need to perform asynchronous actions. See Plugins/PipeReader.hs for an example.

run can be used for simpler plugins. If you define only run the plugin will be run every second. To overwrite this default you just need to implement rate, which must return the number of tenth of seconds between every successive runs. See Plugins/HelloWorld.hs for an example of a plugin that runs just once, and Plugins/Date.hs for one that implements rate.

Notice that Date could be implemented as:

    instance Exec Date where
        alias (Date _ a _) = a
        start (Date f _ r) = date f r

    date :: String -> Int -> (String -> IO ()) -> IO ()
    date format r callback = do go
        where go = do
                t <- toCalendarTime =<< getClockTime
                callback $ formatCalendarTime defaultTimeLocale format t
                tenthSeconds r >> go

This implementation is equivalent to the one you can read in Plugins/Date.hs.

alias is the name to be used in the output template. Default alias will be the data type constructor.

Implementing a plugin requires importing the plugin API (the Exec class definition), that is exported by Plugins.hs. So you just need to import it in your module with:

    import Plugins

After that your type constructor can be used as an argument for the Runnable type constructor Run in the commands list of the configuration options.

This requires importing your plugin into Config.hs and adding you type to the type list in the type signature of Config.runnableTypes.

For a very basic example see Plugins/HelloWorld.hs or the other plugins that are distributed with Xmobar.

Installing/Removing a Plugin

Installing a plugin should require 3 steps. Here we are going to install the HelloWorld plugin that comes with Xmobar:

import the plugin module in Config.hs, by adding:
```
import Plugins.HelloWorld
```
add the plugin data type to the list of data types in the type signature of runnableTypes in Config.hs. For instance, for the HelloWorld plugin, change runnableTypes into:
```
runnableTypes :: (Command,(Monitors,(HelloWorld,())))
runnableTypes = undefined
```
Rebuild and reinstall Xmobar. Now test it with:
```
xmobar Plugins/helloworld.config
```

As you may see in the example configuration file, the plugin can be used by adding, in the commands list:

    Run HelloWorld

and, in the output template, the alias of the plugin:

    %helloWorld%

That's it.

To remove a plugin, just remove its type from the type signature of runnableTypes and remove the imported modules.

To remove the system monitor plugin:

remove, from Config.hs, the line
```
import Plugins.Monitors
```

in Config.hs change

 runnableTypes :: (Command,(Monitors,()))
 runnableTypes = undefined

 runnableTypes :: (Command,())
 runnableTypes = undefined

rebuild Xmobar.

Credits

Thanks to Robert Manea and Spencer Janssen for their help in understanding how X works. They gave me suggestions on how to solve many problems with Xmobar.

Thanks to Claus Reinke for make me understand existential types (or at least for letting me think I grasp existential types...;-).

Xmobar incorporates patches from: Krzysztof Kosciuszkiewicz, Spencer Janssen, Jens Petersen, Dmitry Kurochkin, and Lennart Kolmodin.

Useful links

The Xmobar home page

The XMonad home page

Xmobars darcs repository

To understand the internal mysteries of Xmobar you may try reading this tutorial on X Window Programming in Haskell.

Author

Andrea Rossato

andrea.rossato at unibz.it

Legal

This software is released under a BSD-style license. See LICENSE for more details.