#+title: Plugins and monitors

* System monitor plugins

  This is the description of the system monitor plugins available in
  xmobar. Some of them are only installed when an optional build
  option is set: we mention that fact, when needed, in their
  description.

  Each monitor has an =alias= to be used in the output
  template. Monitors may have default aliases, see the documentation
  of the monitor in question.

  There are two types of arguments: ones that all monitors share (the
  so called /default monitor arguments/) and arguments that are specific
  to a certain monitor.

  All Monitors accept a common set of arguments, described below in
  [[Default Monitor Arguments]]. Some monitors also accept additional
  options that are specific to them. When specifying the list of
  arguments in your configuration, the common options come first,
  followed by =--=, followed by any monitor-specific options. For
  example, the following [[=Battery Args RefreshRate=][Battery]] configuration first sets the global
  =template= and =Low= arguments and then specifies the battery-specific
  =off= option.

  #+begin_src haskell
    Run Battery
      [ "--template", "<acstatus>"
      , "--Low"     , "15"
      -- battery specific options start here.
      , "--"
      , "--off"     , "<left> (<timeleft>)"
      ]
      100
  #+end_src

  See also [[#interfacing-with-window-managers][Interfacing with window managers]] below for a collection of plugins
  that let you interact and control xmobar from window managers.

** Icon Patterns

   Some monitors allow usage of strings that depend on some integer
   value from 0 to 8 by replacing all occurrences of =%%= with it
   (i.e. =<icon=/path/to/icon_%%.xpm/>= will be interpreted as
   =<icon=/path/to/icon_3.xpm/>= when the value is =3=, also =%= is
   interpreted as =%=, =%%= as =3=, =%%%= as =3%=, =%%%%= as =33= and so
   on). Essentially it allows to replace vertical bars with custom
   icons. For example,

   #+begin_src haskell
     Run Brightness
       [ "-t", "<ipat>"
       , "--"
       , "--brightness-icon-pattern", "<icon=bright_%%.xpm/>"
       ] 30
   #+end_src

   Will display =bright_0.xpm= to =bright_8.xpm= depending on current
   brightness value.

** Default monitor arguments

   These are the options available for all monitors:

   - =-t= /string/ Output template

     - Template for the monitor output. Field names must be enclosed
       between pointy brackets (=<foo>=) and will be substituted by the
       computed values. You can also specify the foreground (and
       optionally, background) color for a region by bracketing it between
       =<fc=fgcolor>= (or =<fc=fgcolor,bgcolor>=) and =</fc>=. The rest of
       the template is output verbatim.
     - Long option: =--template=
     - Default value: per monitor (see above).

   - =-H= /number/ The high threshold.

     - Numerical values higher than /number/ will be displayed with the
       color specified by =-h= (see below).
     - Long option: =--High=
     - Default value: 66

   - =-L= /number/ The low threshold.

     - Numerical values higher than /number/ and lower than the high
       threshold will be displayed with the color specified by =-n= (see
       below). Values lower than /number/ will use the =-l= color.
     - Long option: =--Low=
     - Default value: 33

   - =-h= /color/ High threshold color.

     - Color for displaying values above the high threshold. /color/ can be
       either a name (e.g. "blue") or an hexadecimal RGB (e.g. "#FF0000").
     - Long option: =--high=
     - Default: none (use the default foreground).

   - =-n= /color/ Color for 'normal' values

     - Color used for values greater than the low threshold but lower than
       the high one.
     - Long option: =--normal=
     - Default: none (use the default foreground).

   - =-l= /color/ The low threshold color

     - Color for displaying values below the low threshold.
     - Long option: =--low=
     - Default: none (use the default foreground).

   - =-S= /boolean/ Display optional suffixes

     - When set to a true designator ("True", "Yes" or "On"), optional
       value suffixes such as the '%' symbol or optional units will be
       displayed.
     - Long option: =--suffix=
     - Default: False.

   - =-p= /number/ Percentages padding

     - Width, in number of digits, for quantities representing percentages.
       For instance =-p 3= means that all percentages in the monitor will
       be represented using 3 digits.
     - Long option: =--ppad=
     - Default value: 0 (don't pad)

   - =-d= /number/ Decimal digits

     - Number of digits after the decimal period to use in float values.
     - Long option: =--ddigits=
     - Default value: 0 (display only integer part)

   - =-m= /number/ Minimum field width

     - Minimum width, in number of characters, of the fields in the monitor
       template. Values whose printed representation is shorter than this
       value will be padded using the padding characters given by the =-c=
       option with the alignment specified by =-a= (see below).
     - Long option: =--minwidth=
     - Default: 0

   - =-M= /number/ Maximum field width

     - Maximum width, in number of characters, of the fields in the monitor
       template. Values whose printed representation is longer than this
       value will be truncated.
     - Long option: =--maxwidth=
     - Default: 0 (no maximum width)

   - =-e= /string/ Maximum width ellipsis

     - Ellipsis to be added to the field when it has reached its max width.
     - Long option: =--maxwidthellipsis=
     - Default: "" (no ellipsis)

   - =-w= /number/ Fixed field width

     - All fields will be set to this width, padding or truncating as
       needed.
     - Long option: =--width=
     - Default: 0 (variable width)

   - =-T= /number/ Maximum total width

     - Maximum total width of the text.
     - Long option: =--maxtwidth=
     - Default: 0 (no limit)

   - =-E= /string/ Maximum total width ellipsis

     - Ellipsis to be added to the total text when it has reached its max
       width.
     - Long option: =--maxtwidthellipsis=
     - Default: "" (no ellipsis)

   - =-c= /string/

     - Characters used for padding. The characters of /string/ are used
       cyclically. E.g., with =-P +- -w 6=, a field with value "foo" will
       be represented as "+-+foo".
     - Long option: =--padchars=
     - Default value: " "

   - =-a= r|l Field alignment

     - Whether to use right (r) or left (l) alignment of field values when
       padding.
     - Long option: =--align=
     - Default value: r (padding to the left)

   - =-b= /string/ Bar background

     - Characters used, cyclically, to draw the background of bars. For
       instance, if you set this option to "·.", an empty bar will look
       like this: =·.·.·.·.·.=
     - Long option: =--bback=
     - Default value: ":"

   - =-f= /string/ Bar foreground

     - Characters used, cyclically, to draw the foreground of bars.
     - Long option: =--bfore=
     - Default value: "#"

   - =-W= /number/ Bar width

     - Total number of characters used to draw bars.
     - Long option: =--bwidth=
     - Default value: 10
     - Special value: 0. When this parameter is 0, the percentage to
       display is interpreted as a position in the bar foreground string
       (given by =-f=), and the character at that position is displayed.

   - =-x= /string/ N/A string

     - String to be used when the monitor is not available
     - Long option: =--nastring=
     - Default value: "N/A"

     Commands' arguments must be set as a list. E.g.:

     #+begin_src haskell
       Run Weather "EGPF" ["-t", "<station>: <tempC>C"] 36000
     #+end_src

     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:

     #+begin_src shell
       Glasgow Airport: 16.0C
     #+end_src

** Battery monitors
*** =Battery Args RefreshRate=

    Same as

    #+begin_src haskell
      BatteryP ["BAT", "BAT0", "BAT1", "BAT2"] Args RefreshRate
    #+end_src

*** =BatteryP Dirs Args RefreshRate=
    :PROPERTIES:
    :CUSTOM_ID: batteryp-dirs-args-refreshrate
    :END:

    - Aliases to =battery=

    - Dirs: list of directories in =/sys/class/power_supply/= where to look
      for the ACPI files of each battery. Example: =["BAT0","BAT1","BAT2"]=.
      Only up to 3 existing directories will be searched.

    - Args: default monitor arguments, plus the following specific ones
      (these options, being specific to the monitor, are to be specified
      after a =--= in the argument list):

      - =-O=: string for AC "on" status (default: "On")
      - =-i=: string for AC "idle" status (default: "On")
      - =-o=: string for AC "off" status (default: "Off")
      - =-L=: low power (=watts=) threshold (default: 10)
      - =-H=: high power threshold (default: 12)
      - =-l=: color to display power lower than the =-L= threshold
      - =-m=: color to display power lower than the =-H= threshold
      - =-h=: color to display power higher than the =-H= threshold
      - =-p=: color to display positive power (battery charging)
      - =-f=: file in =/sys/class/power_supply= with AC info (default:
        "AC/online")
      - =-A=: a number between 0 and 100, threshold below which the action
        given by =-a=, if any, is performed (default: 5)
      - =-a=: a string with a system command that is run when the percentage
        left in the battery is less or equal than the threshold given by the
        =-A= option. If not present, no action is undertaken.
      - =-P=: to include a percentage symbol in =left=.
      - =--on-icon-pattern=: dynamic string for current battery charge when
        AC is "on" in =leftipat=.
      - =--off-icon-pattern=: dynamic string for current battery charge when
        AC is "off" in =leftipat=.
      - =--idle-icon-pattern=: dynamic string for current battery charge
        when AC is "idle" in =leftipat=.
      - =--lows=: string for AC "off" status and power lower than the =-L=
        threshold (default: "")
      - =--mediums=: string for AC "off" status and power lower than the
        =-H= threshold (default: "")
      - =--highs=: string for AC "off" status and power higher than the =-H=
        threshold (default: "")

    - Variables that can be used with the =-t/--template= argument:
      =left=, =leftbar=, =leftvbar=, =leftipat=, =timeleft=, =watts=,
      =acstatus=

    - Default template: =Batt: <watts>, <left>% / <timeleft>=

    - Example (note that you need "--" to separate regular monitor options
      from Battery's specific ones):

      #+begin_src haskell
        Run BatteryP ["BAT0"]
                     ["-t", "<acstatus><watts> (<left>%)",
                      "-L", "10", "-H", "80", "-p", "3",
                      "--", "-O", "<fc=green>On</fc> - ", "-i", "",
                      "-L", "-15", "-H", "-5",
                      "-l", "red", "-m", "blue", "-h", "green",
                      "-a", "notify-send -u critical 'Battery running out!!'",
                      "-A", "3"]
                     600
      #+end_src

      In the above example, the thresholds before the =--= separator affect
      only the =<left>= and =<leftbar>= fields, while those after the
      separator affect how =<watts>= is displayed. For this monitor, neither
      the generic nor the specific options have any effect on =<timeleft>=.
      We are also telling the monitor to execute the unix command
      =notify-send= when the percentage left in the battery reaches 6%.

      It is also possible to specify template variables in the =-O= and =-o=
      switches, as in the following example:

      #+begin_src haskell
        Run BatteryP ["BAT0"]
                     ["-t", "<acstatus>"
                     , "-L", "10", "-H", "80"
                     , "-l", "red", "-h", "green"
                     , "--", "-O", "Charging", "-o", "Battery: <left>%"
                     ] 10
      #+end_src

    - The "idle" AC state is selected whenever the AC power entering the
      battery is zero.

*** =BatteryN Dirs Args RefreshRate Alias=

    Works like =BatteryP=, but lets you specify an alias for the
    monitor other than "battery". Useful in case you one separate
    monitors for more than one battery.
** Cpu and Memory monitors
*** =Cpu Args RefreshRate=

    - Aliases to =cpu=
    - Args: default monitor arguments, plus:

      - =--load-icon-pattern=: dynamic string for cpu load in =ipat=

    - Thresholds refer to percentage of CPU load
    - Variables that can be used with the =-t/--template= argument:
      =total=, =bar=, =vbar=, =ipat=, =user=, =nice=, =system=, =idle=,
      =iowait=
    - Default template: =Cpu: <total>%=

*** =MultiCpu Args RefreshRate=

    - Aliases to =multicpu=
    - Args: default monitor arguments, plus:

      - =--load-icon-pattern=: dynamic string for overall cpu load in
        =ipat=.
      - =--load-icon-patterns=: dynamic string for each cpu load in
        =autoipat=, =ipat{i}=. This option can be specified several times.
        nth option corresponds to nth cpu.
      - =--fallback-icon-pattern=: dynamic string used by =autoipat= and
        =ipat{i}= when no =--load-icon-patterns= has been provided for
        =cpu{i}=
      - =--contiguous-icons=: flag (no value needs to be provided) that
        causes the load icons to be drawn without padding.

    - Thresholds refer to percentage of CPU load
    - Variables that can be used with the =-t/--template= argument:
      =autototal=, =autobar=, =autovbar=, =autoipat=, =autouser=,
      =autonice=, =autosystem=, =autoidle=, =total=, =bar=, =vbar=, =ipat=,
      =user=, =nice=, =system=, =idle=, =total0=, =bar0=, =vbar0=, =ipat0=,
      =user0=, =nice0=, =system0=, =idle0=, ... The auto* variables
      automatically detect the number of CPUs on the system and display one
      entry for each.
    - Default template: =Cpu: <total>%=

*** =CpuFreq Args RefreshRate=

    - Aliases to =cpufreq=

    - Args: default monitor arguments

    - Thresholds refer to frequency in GHz

    - Variables that can be used with the =-t/--template= argument:
      =cpu0=, =cpu1=, .., =cpuN=, give the current frequency of the
      respective CPU core, and =max=, =min= and =avg= the maximum, minimum
      and average frequency over all available cores.

    - Default template: =Freq: <cpu0>GHz=

    - This monitor requires the ~acpi_cpufreq~ module to be loaded in kernel

    - Example:

      #+begin_src haskell
        Run CpuFreq ["-t", "Freq:<cpu0>|<cpu1>GHz", "-L", "0", "-H", "2",
                     "-l", "lightblue", "-n","white", "-h", "red"] 50

        Run CpuFreq ["-t", "Freq:<avg> GHz", "-L", "0", "-H", "2",
                     "-l", "lightblue", "-n","white", "-h", "red"] 50
      #+end_src

*** =CoreTemp Args RefreshRate=

    - Aliases to =coretemp=

    - Args: default monitor arguments

    - Thresholds refer to temperature in degrees

    - Variables that can be used with the =-t/--template= argument:
      =core0=, =core1=, .., =coreN=

    - Default template: =Temp: <core0>C=

    - This monitor requires coretemp module to be loaded in kernel

    - Example:

      #+begin_src haskell
        Run CoreTemp ["-t", "Temp:<core0>|<core1>C",
                      "-L", "40", "-H", "60",
                      "-l", "lightblue", "-n", "gray90", "-h", "red"] 50
      #+end_src

*** =MultiCoreTemp Args RefreshRate=

    - Aliases to =multicoretemp=

    - Args: default monitor arguments, plus:

      - =--max-icon-pattern=: dynamic string for overall cpu load in
        =maxipat=.
      - =--avg-icon-pattern=: dynamic string for overall cpu load in
        =avgipat=.
      - =--mintemp=: temperature in degree Celsius, that sets the lower
        limit for percentage calculation.
      - =--maxtemp=: temperature in degree Celsius, that sets the upper
        limit for percentage calculation.
      - =--hwmon-path=: this monitor tries to find coretemp devices by
        looking for them in directories following the pattern
        =/sys/bus/platform/devices/coretemp.*/hwmon/hwmon*=, but some
        processors (notably Ryzen) might expose those files in a different
        tree (e.g., Ryzen) puts them somewhere in "/sys/class/hwmon/hwmon*",
        and the lookup is most costly. With this option, it is possible to
        explicitly specify the full path to the directory where the
        =tempN_label= and =tempN_input= files are located.

    - Thresholds refer to temperature in degree Celsius

    - Variables that can be used with the =-t/--template= argument: =max=,
      =maxpc=, =maxbar=, =maxvbar=, =maxipat=, =avg=, =avgpc=, =avgbar=,
      =avgvbar=, =avgipat=, =core0=, =core1=, ..., =coreN=

      The /pc, /bar, /vbar and /ipat variables are showing percentages on
      the scale defined by =--mintemp= and =--maxtemp=. The max* and avg*
      variables to the highest and the average core temperature.

    - Default template: =Temp: <max>°C - <maxpc>%=

    - This monitor requires coretemp module to be loaded in kernel

    - Example:

      #+begin_src haskell
        Run MultiCoreTemp ["-t", "Temp: <avg>°C | <avgpc>%",
                           "-L", "60", "-H", "80",
                           "-l", "green", "-n", "yellow", "-h", "red",
                           "--", "--mintemp", "20", "--maxtemp", "100"] 50
      #+end_src

*** =K10Temp Slot Args RefreshRate=

    - Aliases to =k10temp=

    - Slot: The PCI slot address of the k10temp device as a string.  You
      can find it as a subdirectory in =/sys/bus/pci/drivers/k10temp/=.

    - Args: default monitor arguments

    - Thresholds refer to temperature in degrees

    - Variables that can be used with the =-t/--template= argument:
      =Tctl=, =Tdie=, =Tccd1=, .., =Tccd8=

    - Default template: =Temp: <Tdie>C=

    - This monitor requires k10temp module to be loaded in kernel

    - It is important to note that not all measurements are available
      on on all models of processor. Of particular importance - Tdie
      (used in the default template) may not be present on processors
      prior to Zen (17h). Tctl, however, may be offset from the real
      temperature and so is not used by default.

    - Example:

      #+begin_src haskell
        Run K10Temp "0000:00:18.3"
                    ["-t", "Temp: <Tdie>C|<Tccd1>C",
                     "-L", "40", "-H", "60",
                     "-l", "lightblue", "-n", "gray90", "-h", "red"]
                    50
      #+end_src


*** =Memory Args RefreshRate=

    - Aliases to =memory=
    - Args: default monitor arguments, plus:

      - =--used-icon-pattern=: dynamic string for used memory ratio in
        =usedipat=.
      - =--free-icon-pattern=: dynamic string for free memory ratio in
        =freeipat=.
      - =--available-icon-pattern=: dynamic string for available memory
        ratio in =availableipat=.
      - =--scale=: sizes (total, free, etc.) are reported in units of
        ~Mb/scale~, with scale defaulting to 1.0.  So, for
        instance, to get sizes reported in Gb, set this parameter
        to 1024.

    - Thresholds refer to percentage of used memory
    - Variables that can be used with the =-t/--template= argument:
      =total=, =free=, =buffer=, =cache=, =available=, =used=, =usedratio=,
      =usedbar=, =usedvbar=, =usedipat=, =freeratio=, =freebar=, =freevbar=,
      =freeipat=, =availableratio=, =availablebar=, =availablevbar=,
      =availableipat=

    - Default template: =Mem: <usedratio>% (<cache>M)=

    - Examples:

      #+begin_src haskell
        -- A monitor reporting memory used in Gb
        Memory [ "-t", "<used> Gb", "--", "--scale", "1024"] 20
        -- As above, but using one decimal digit to print numbers
        Memory [ "-t", "<used> Gb", "-d", "1", "--", "--scale", "1024"] 20
      #+end_src

*** =Swap Args RefreshRate=

    - Aliases to =swap=
    - Args: default monitor arguments
    - Thresholds refer to percentage of used swap
    - Variables that can be used with the =-t/--template= argument:
      =total=, =used=, =free=, =usedratio=
    - Default template: =Swap: <usedratio>%=

** Date monitors
*** =Date Format Alias RefreshRate=

    - Format is a time format string, as accepted by the standard ISO C
      =strftime= function (or Haskell's =formatCalendarTime=).  Basically,
      if =date +"my-string"= works with your command then =Date= will handle
      it correctly.

    - Timezone changes are picked up automatically every minute.

    - Sample usage:

      #+begin_src haskell
        Run Date "%a %b %_d %Y <fc=#ee9a00>%H:%M:%S</fc>" "date" 10
      #+end_src

*** =DateZone Format Locale Zone Alias RefreshRate=

    A variant of the =Date= monitor where one is able to explicitly set the
    time-zone, as well as the locale.

    - The format of =DateZone= is exactly the same as =Date=.

    - If =Locale= is =""= (the empty string) the default locale of the
      system is used, otherwise use the given locale. If there are more
      instances of =DateZone=, using the empty string as input for =Locale=
      is not recommended.

    - =Zone= is the name of the =TimeZone=. It is assumed that the time-zone
      database is stored in =/usr/share/zoneinfo/=. If the empty string is
      given as =Zone=, the default system time is used.

    - Sample usage:

      #+begin_src haskell
        Run DateZone "%a %H:%M:%S" "de_DE.UTF-8" "Europe/Vienna" "viennaTime" 10
      #+end_src
** Disk monitors
*** =DiskU Disks Args RefreshRate=

    - Aliases to =disku=

    - Disks: list of pairs of the form (device or mount point, template),
      where the template can contain =<size>=, =<free>=, =<used>=, =<freep>=
      or =<usedp>=, =<freebar>=, =<freevbar>=, =<freeipat>=, =<usedbar>=,
      =<usedvbar>= or =<usedipat>= for total, free, used, free percentage
      and used percentage of the given file system capacity.

    - Thresholds refer to usage percentage.

    - Args: default monitor arguments. =-t/--template= is ignored. Plus

      - =--free-icon-pattern=: dynamic string for free disk space in
        =freeipat=.
      - =--used-icon-pattern=: dynamic string for used disk space in
        =usedipat=.

    - Default template: none (you must specify a template for each file
      system).

    - Example:

      #+begin_src haskell
        DiskU [("/", "<used>/<size>"), ("sdb1", "<usedbar>")]
              ["-L", "20", "-H", "50", "-m", "1", "-p", "3"]
              20
      #+end_src

*** =DiskIO Disks Args RefreshRate=

    - Aliases to =diskio=

    - Disks: list of pairs of the form (device or mount point, template),
      where the template can contain =<total>=, =<read>=, =<write>= for
      total, read and write speed, respectively, as well as =<totalb>=,
      =<readb>=, =<writeb>=, which report number of bytes during the last
      refresh period rather than speed. There are also bar versions of each:
      =<totalbar>=, =<totalvbar>=, =<totalipat>=, =<readbar>=, =<readvbar>=,
      =<readipat>=, =<writebar>=, =<writevbar>=, and =<writeipat>=; and
      their "bytes" counterparts: =<totalbbar>=, =<totalbvbar>=,
      =<totalbipat>=, =<readbbar>=, =<readbvbar>=, =<readbipat>=,
      =<writebbar>=, =<writebvbar>=, and =<writebipat>=.

    - Thresholds refer to speed in b/s

    - Args: default monitor arguments. =-t/--template= is ignored. Plus

      - =--total-icon-pattern=: dynamic string for total disk I/O in
        =<totalipat>=.
      - =--write-icon-pattern=: dynamic string for write disk I/O in
        =<writeipat>=.
      - =--read-icon-pattern=: dynamic string for read disk I/O in
        =<readipat>=.

    - Default template: none (you must specify a template for each file
      system).

    - Example:

      #+begin_src haskell
        DiskIO [("/", "<read> <write>"), ("sdb1", "<total>")] [] 10
      #+end_src

** Keyboard and screen monitors
*** =Kbd Opts=

    - Registers to XKB/X11-Events and output the currently active keyboard
      layout. Supports replacement of layout names.

    - Aliases to =kbd=

    - Opts is a list of tuples:

      - first element of the tuple is the search string
      - second element of the tuple is the corresponding replacement

    - Example:

      #+begin_src haskell
        Run Kbd [("us(dvorak)", "DV"), ("us", "US")]
      #+end_src

*** =Brightness Args RefreshRate=

    - Aliases to =bright=

    - Args: default monitor arguments, plus the following specif ones:

      - =-D=: directory in =/sys/class/backlight/= with files in it
        (default: "acpi_video0")
      - =-C=: file with the current brightness (default: actual_brightness)
      - =-M=: file with the maximum brightness (default: max_brightness)
      - =--brightness-icon-pattern=: dynamic string for current brightness
        in =ipat=.

    - Variables that can be used with the =-t/--template= argument:
      =vbar=, =percent=, =bar=, =ipat=

    - Default template: =<percent>=

    - Example:

      #+begin_src haskell
        Run Brightness ["-t", "<bar>"] 60
      #+end_src
*** =Locks=

    - Displays the status of Caps Lock, Num Lock and Scroll Lock.

    - Aliases to =locks=

    - Example:

      #+begin_src haskell
        Run Locks
      #+end_src

** Load and Process monitors
*** =Load Args RefreshRate=

    - Aliases to =load=

    - Args: default monitor arguments. The low and high thresholds
      (=-L= and =-H=) refer to load average values.

    - Variables that can be used with the =-t/--template= argument:
      =load1=, =load5=, =load15=.

    - Default template: =Load: <load1>=.

    - Displays load averages for the last 1, 5 or 15 minutes as
      reported by, e.g., ~uptime(1)~.  The displayed values are float,
      so that the ~"-d"~ option will control how many decimal digits
      are shown (zero by default).

    - Example: to have 2 decimal digits displayed, with a low
      threshold at 1.0 and a high one at 3, you'd write something
      like:

      #+begin_src haskell
        Run Load ["-t" , "<load1> <load5> <load15>"
                 , "-L", "1", "-H", "3", "-d", "2"]) 300
      #+end_src

*** =TopProc Args RefreshRate=

    - Aliases to =top=
    - Args: default monitor arguments. The low and high thresholds (=-L= and
      =-H=) denote, for memory entries, the percent of the process memory
      over the total amount of memory currently in use and, for cpu entries,
      the activity percentage (i.e., the value of =cpuN=, which takes values
      between 0 and 100).
    - Variables that can be used with the =-t/--template= argument: =no=,
      =name1=, =cpu1=, =both1=, =mname1=, =mem1=, =mboth1=, =name2=, =cpu2=,
      =both2=, =mname2=, =mem2=, =mboth2=, ...
    - Default template: =<both1>=
    - Displays the name and cpu/mem usage of running processes (=bothn= and
      =mboth= display both, and is useful to specify an overall maximum
      and/or minimum width, using the =-m/-M= arguments. =no= gives the
      total number of processes.

*** =TopMem Args RefreshRate=

    - Aliases to =topmem=
    - Args: default monitor arguments. The low and high thresholds (=-L= and
      =-H=) denote the percent of the process memory over the total amount
      of memory currently in use.
    - Variables that can be used with the =-t/--template= argument:
      =name1=, =mem1=, =both1=, =name2=, =mem2=, =both2=, ...
    - Default template: =<both1>=
    - Displays the name and RSS (resident memory size) of running processes
      (=bothn= displays both, and is useful to specify an overall maximum
      and/or minimum width, using the =-m/-M= arguments.

** Thermal monitors
*** =ThermalZone Number Args RefreshRate=

    - Aliases to "thermaln": so =ThermalZone 0 []= can be used in template
      as =%thermal0%=

    - Thresholds refer to temperature in degrees

    - Args: default monitor arguments

    - Variables that can be used with the =-t/--template= argument: =temp=

    - Default template: =<temp>C=

    - This plugin works only on systems with devices having thermal zone.
      Check directories in =/sys/class/thermal= for possible values of the
      zone number (e.g., 0 corresponds to =thermal_zone0= in that
      directory).

    - Example:

      #+begin_src haskell
        Run ThermalZone 0 ["-t","<id>: <temp>C"] 30
      #+end_src

*** =Thermal Zone Args RefreshRate=

    - *This plugin is deprecated. Use =ThermalZone= instead.*

    - Aliases to the Zone: so =Thermal "THRM" []= can be used in template as
      =%THRM%=

    - Args: default monitor arguments

    - Thresholds refer to temperature in degrees

    - Variables that can be used with the =-t/--template= argument: =temp=

    - Default template: =Thm: <temp>C=

    - This plugin works only on systems with devices having thermal zone.
      Check directories in /proc/acpi/thermal_zone for possible values.

    - Example:

      #+begin_src haskell
        Run Thermal "THRM" ["-t","iwl4965-temp: <temp>C"] 50
      #+end_src

** Volume monitors
*** =Volume Mixer Element Args RefreshRate=

    - Aliases to the mixer name and element name separated by a
      colon. Thus, =Volume "default" "Master" [] 10= can be used as
      =%default:Master%=.
    - Args: default monitor arguments. Also accepts:

      - =-O= /string/ On string

        - The string used in place of =<status>= when the mixer element is
          on. Defaults to "[on]".
        - Long option: =--on=

      - =-o= /string/ Off string

        - The string used in place of =<status>= when the mixer element is
          off. Defaults to "[off]".
        - Long option: =--off=

      - =-C= /color/ On color

        - The color to be used for =<status>= when the mixer element is on.
          Defaults to "green".
        - Long option: =--onc=

      - =-c= /color/ Off color

        - The color to be used for =<status>= when the mixer element is off.
          Defaults to "red".
        - Long option: =--offc=

      - =--highd= /number/ High threshold for dB. Defaults to -5.0.
      - =--lowd= /number/ Low threshold for dB. Defaults to -30.0.
      - =--volume-icon-pattern= /string/ dynamic string for current volume
        in =volumeipat=.
      - =-H= /number/ High threshold for volume (in %). Defaults to 60.0.

        - Long option: =--highv=

      - =-L= /number/ Low threshold for volume (in %). Defaults to 20.0.

        - Long option: =--lowv=

      - =-h=: /string/ High string

        - The string added in front of =<status>= when the mixer element is
          on and the volume percentage is higher than the =-H= threshold.
          Defaults to "".
        - Long option: =--highs=

      - =-m=: /string/ Medium string

        - The string added in front of =<status>= when the mixer element is
          on and the volume percentage is lower than the =-H= threshold.
          Defaults to "".
        - Long option: =--mediums=

      - =-l=: /string/ Low string

        - The string added in front of =<status>= when the mixer element is
          on and the volume percentage is lower than the =-L= threshold.
          Defaults to "".
        - Long option: =--lows=

    - Variables that can be used with the =-t/--template= argument:
      =volume=, =volumebar=, =volumevbar=, =volumeipat=, =dB=, =status=,
      =volumestatus=
    - Note that =dB= might only return 0 on your system. This is known to
      happen on systems with a pulseaudio backend.
    - Default template: =Vol: <volume>% <status>=
    - Requires the package [[http://hackage.haskell.org/package/alsa-core][alsa-core]] and [[http://hackage.haskell.org/package/alsa-mixer][alsa-mixer]] installed in your
      system. In addition, to activate this plugin you must pass the
      =with_alsa= flag during compilation.

*** =Alsa Mixer Element Args=

    Like [[=Volume Mixer Element Args RefreshRate=][Volume]] but with the following differences:

    - Uses event-based refreshing via =alsactl monitor= instead of polling,
      so it will refresh instantly when there's a volume change, and won't
      use CPU until a change happens.
    - Aliases to =alsa:= followed by the mixer name and element name
      separated by a colon. Thus, =Alsa "default" "Master" []= can be used
      as =%alsa:default:Master%=.
    - Additional options (after the =--=):
      - =--alsactl=/path/to/alsactl=: If this option is not specified,
        =alsactl= will be sought in your =PATH= first, and failing that, at
        =/usr/sbin/alsactl= (this is its location on Debian systems.
        =alsactl monitor= works as a non-root user despite living in
        =/usr/sbin=.).
      - =stdbuf= (from coreutils) must be (and most probably already is) in
        your =PATH=.

** Mail monitors
*** =Mail Args Alias=

    - Args: list of maildirs in form =[("name1","path1"),...]=. Paths may
      start with a '~' to expand to the user's home directory.

    - This plugin requires inotify support in your Linux kernel and the
      [[http://hackage.haskell.org/package/hinotify/][hinotify]] package. To activate, pass the =with_inotify= flag during
      compilation.

    - Example:

      #+begin_src haskell
        Run Mail [("inbox", "~/var/mail/inbox"),
                  ("lists", "~/var/mail/lists")]
                 "mail"
      #+end_src

*** =MailX Args Opts Alias=

    - Args: list of maildirs in form =[("name1","path1","color1"),...]=.
      Paths may start with a '~' to expand to the user's home directory.
      When mails are present, counts are displayed with the given name and
      color.

    - Opts is a possibly empty list of options, as flags. Possible values:
      -d dir --dir dir a string giving the base directory where maildir
      files with a relative path live. -p prefix --prefix prefix a string
      giving a prefix for the list of displayed mail counts -s suffix
      --suffix suffix a string giving a suffix for the list of displayed
      mail counts

    - This plugin requires inotify support in your Linux kernel and the
      [[http://hackage.haskell.org/package/hinotify/][hinotify]] package. To activate, pass the =with_inotify= flag during
      compilation.

    - Example:

      #+begin_src haskell
        Run MailX [("I", "inbox", "green"),
                   ("L", "lists", "orange")]
                  ["-d", "~/var/mail", "-p", " ", "-s", " "]
                  "mail"
      #+end_src

*** =MBox Mboxes Opts Alias=

    - Mboxes a list of mbox files of the form =[("name", "path", "color")]=,
      where name is the displayed name, path the absolute or relative (to
      BaseDir) path of the mbox file, and color the color to use to display
      the mail count (use an empty string for the default).

    - Opts is a possibly empty list of options, as flags. Possible values:
      -a --all (no arg) Show all mailboxes, even if empty. -u (no arg) Show
      only the mailboxes' names, sans counts. -d dir --dir dir a string
      giving the base directory where mbox files with a relative path live.
      -p prefix --prefix prefix a string giving a prefix for the list of
      displayed mail counts -s suffix --suffix suffix a string giving a
      suffix for the list of displayed mail counts

    - Paths may start with a '~' to expand to the user's home directory.

    - This plugin requires inotify support in your Linux kernel and the
      [[http://hackage.haskell.org/package/hinotify/][hinotify]] package. To activate, pass the =with_inotify= flag during
      compilation.

    - Example. The following command look for mails in =/var/mail/inbox= and
      =~/foo/mbox=, and will put a space in front of the printed string
      (when it's not empty); it can be used in the template with the alias
      =mbox=:

      #+begin_src haskell
        Run MBox [("I ", "inbox", "red"), ("O ", "~/foo/mbox", "")]
                 ["-d", "/var/mail/", "-p", " "] "mbox"
      #+end_src

*** =NotmuchMail Alias Args Rate=

    This plugin checks for new mail, provided that this mail is indexed by
    =notmuch=. In the =notmuch= spirit, this plugin checks for new *threads*
    and not new individual messages.

    - Alias: What name the plugin should have in your template string.

    - Args: A list of =MailItem= s of the form

      #+begin_src haskell
        [ MailItem "name" "address" "query"
        ...
        ]
      #+end_src

      where

      - =name= is what gets printed in the status bar before the number of
        new threads.
      - =address= is the e-mail address of the recipient, i.e. we only query
        mail that was send to this particular address (in more concrete
        terms, we pass the address to the =to:= constructor when performing
        the search). If =address= is empty, we search through all unread
        mail, regardless of whom it was sent to.
      - =query= is funneled to =notmuch search= verbatim. For the general
        query syntax, consult =notmuch search --help=, as well as
        =notmuch-search-terms(7)=. Note that the =unread= tag is *always*
        added in front of the query and composed with it via an *and*.

    - Rate: Rate with which to update the plugin (in deciseconds).

    - Example:

      - A single =MailItem= that displays all unread threads from the given
        address:

        #+begin_src haskell
          MailItem "mbs:" "soliditsallgood@mailbox.org" ""
        #+end_src

      - A single =MailItem= that displays all unread threads with
        "[My-Subject]" somewhere in the title:

        #+begin_src haskell
          MailItem "S:" "" "subject:[My-Subject]"
        #+end_src

      - A full example of a =NotmuchMail= configuration:

        #+begin_src haskell
          Run NotmuchMail "mail"  -- name for the template string
            [ -- All unread mail to the below address, but nothing that's tagged
              -- with @lists@ or @haskell@.
              MailItem "mbs:"
                       "soliditsallgood@mailbox.org"
                       "not tag:lists and not tag:haskell"

              -- All unread mail that has @[Haskell-Cafe]@ in the subject line.
            , MailItem "C:" "" "subject:[Haskell-Cafe]"

              -- All unread mail that's tagged as @lists@, but not @haskell@.
            , MailItem "H:" "" "tag:lists and not tag:haskell"
            ]
            600                   -- update every 60 seconds
        #+end_src

** Music monitors
*** =MPD Args RefreshRate=

    - This monitor will only be compiled if you ask for it using the
      =with_mpd= flag. It needs [[http://hackage.haskell.org/package/libmpd/][libmpd]] 5.0 or later (available on Hackage).

    - Aliases to =mpd=

    - Args: default monitor arguments. In addition you can provide =-P=,
      =-S= and =-Z=, with an string argument, to represent the playing,
      stopped and paused states in the =statei= template field. The
      environment variables =MPD_HOST= and =MPD_PORT= are used to configure
      the mpd server to communicate with, unless given in the additional
      arguments =-p= (=--port=) and =-h= (=--host=). Also available:

      - =lapsed-icon-pattern=: dynamic string for current track position in
        =ipat=.

    - Variables that can be used with the =-t/--template= argument: =bar=,
      =vbar=, =ipat=, =state=, =statei=, =volume=, =length=, =lapsed=,
      =remaining=, =plength= (playlist length), =ppos= (playlist position),
      =flags= (ncmpcpp-style playback mode), =name=, =artist=, =composer=,
      =performer=, =album=, =title=, =track=, =file=, =genre=, =date=

    - Default template: =MPD: <state>=

    - Example (note that you need "--" to separate regular monitor options
      from MPD's specific ones):

      #+begin_src haskell
        Run MPD ["-t",
                 "<composer> <title> (<album>) <track>/<plength> <statei> [<flags>]",
                 "--", "-P", ">>", "-Z", "|", "-S", "><"] 10
      #+end_src

*** =MPDX Args RefreshRate Alias=

    Like =MPD= but uses as alias its last argument instead of "mpd".

*** =Mpris1 PlayerName Args RefreshRate=

    - Aliases to =mpris1=

    - Requires [[http://hackage.haskell.org/package/dbus][dbus]] and [[http://hackage.haskell.org/package/text][text]] packages. To activate, pass the =with_mpris=
      flag during compilation.

    - PlayerName: player supporting MPRIS v1 protocol. Some players need
      this to be an all lowercase name (e.g. "spotify"), but some others
      don't.

    - Args: default monitor arguments.

    - Variables that can be used with the =-t/--template= argument:
      =album=, =artist=, =arturl=, =length=, =title=, =tracknumber=

    - Default template: =<artist> - <title>=

    - Example:

      #+begin_src haskell
        Run Mpris1 "clementine" ["-t", "<artist> - [<tracknumber>] <title>"] 10
      #+end_src

*** =Mpris2 PlayerName Args RefreshRate=

    - Aliases to =mpris2=

    - Requires [[http://hackage.haskell.org/package/dbus][dbus]] and [[http://hackage.haskell.org/package/text][text]] packages. To activate, pass the =with_mpris=
      flag during compilation.

    - PlayerName: player supporting MPRIS v2 protocol. Some players need
      this to be an all lowercase name (e.g. "spotify"), but some others
      don't.

    - Args: default monitor arguments.

    - Variables that can be used with the =-t/--template= argument:
      =album=, =artist=, =arturl=, =length=, =title=, =tracknumber=,
      =composer=, =genre=

    - Default template: =<artist> - <title>=

    - Example:

      #+begin_src haskell
        Run Mpris2 "spotify" ["-t", "<artist> - [<composer>] <title>"] 10
      #+end_src

** Network monitors
*** =Network Interface Args RefreshRate=

    - Aliases to the interface name: so =Network "eth0" []= can be used as
      =%eth0%=
    - Thresholds refer to velocities expressed in B/s
    - Args: default monitor arguments, plus:

      - =--rx-icon-pattern=: dynamic string for reception rate in =rxipat=.
      - =--tx-icon-pattern=: dynamic string for transmission rate in
        =txipat=.
      - =--up=: string used for the =up= variable value when the interface
        is up.

    - Variables that can be used with the =-t=/=--template= argument: =dev=,
      =rx=, =tx=, =rxbar=, =rxvbar=, =rxipat=, =txbar=, =txvbar=, =txipat=,
      =up=. Reception and transmission rates (=rx= and =tx=) are displayed
      by default as KB/s, without any suffixes, but you can set the =-S= to
      "True" to make them displayed with adaptive units (KB/s, MB/s, etc.).
    - Default template: =<dev>: <rx>KB|<tx>KB=

*** =DynNetwork Args RefreshRate=

    - Active interface is detected automatically
    - Aliases to "dynnetwork"
    - Thresholds are expressed in B/s
    - Args: default monitor arguments, plus:

    - =--rx-icon-pattern=: dynamic string for reception rate in =rxipat=.
    - =--tx-icon-pattern=: dynamic string for transmission rate in =txipat=
    - =--devices=: comma-separated list of devices to show.

    - Variables that can be used with the =-t=/=--template= argument:
      =dev=, =rx=, =tx=, =rxbar=, =rxvbar=, =rxipat=, =txbar=, =txvbar=,
      =txipat=.

      Reception and transmission rates (=rx= and =tx=) are displayed in Kbytes
      per second, and you can set the =-S= to "True" to make them displayed
      with units (the string "KB/s").
      - Default template: =<dev>: <rx>KB|<tx>KB=
      - Example of usage of =--devices= option:

        =["--", "--devices", "wlp2s0,enp0s20f41"]=

*** =Wireless Interface Args RefreshRate=

    - If set to "", first suitable wireless interface is used.
    - Aliases to the interface name with the suffix "wi": thus,
      =Wireless   "wlan0" []= can be used as =%wlan0wi%=, and
      =Wireless "" []= as =%wi%=.
    - Args: default monitor arguments, plus:

      - =--quality-icon-pattern=: dynamic string for connection quality in
        =qualityipat=.

    - Variables that can be used with the =-t=/=--template= argument:
      =ssid=, =signal=, =quality=, =qualitybar=, =qualityvbar=,
      =qualityipat=
    - Thresholds refer to link quality on a =[0, 100]= scale. Note that
      =quality= is calculated from =signal= (in dBm) by a possibly lossy
      conversion. It is also not taking into account many factors such as
      noise level, air busy time, transcievers' capabilities and the others
      which can have drastic impact on the link performance.
    - Default template: =<ssid> <quality>=
    - To activate this plugin you must pass the =with_nl80211= or the
      =with_iwlib= flag during compilation.

** Weather monitors
   :PROPERTIES:
   :CUSTOM_ID: weather-monitors
   :END:
*** =Weather StationID Args RefreshRate=

    - Aliases to the Station ID: so =Weather "LIPB" []= can be used in
      template as =%LIPB%=
    - Thresholds refer to temperature in the selected units
    - Args: default monitor arguments, plus:

      - =--weathers= /string/ : display a default string when the =weather=
        variable is not reported.

        - short option: =-w=
        - Default: ""

      - =--useManager= /bool/ : Whether to use one single manager per
        monitor for managing network connections or create a new one every
        time a connection is made.

        - Short option: =-m=
        - Default: True

    - Variables that can be used with the =-t/--template= argument:
      =station=, =stationState=, =year=, =month=, =day=, =hour=,
      =windCardinal=, =windAzimuth=, =windMph=, =windKnots=, =windMs=,
      =windKmh= =visibility=, =skyCondition=, =weather=, =tempC=, =tempF=,
      =dewPointC=, =dewPointF=, =rh=, =pressure=
    - Default template: =<station>: <tempC>C, rh <rh>% (<hour>)=
    - Retrieves weather information from http://tgftp.nws.noaa.gov. Here is
      an [[https://tgftp.nws.noaa.gov/data/observations/metar/decoded/CYLD.TXT][example]], also showcasing the kind of information that may be
      extracted. Here is [[https://weather.rap.ucar.edu/surface/stations.txt][a sample list of station IDs]].

*** =WeatherX StationID SkyConditions Args RefreshRate=

    - Works in the same way as =Weather=, but takes an additional argument,
      a list of pairs from sky conditions to their replacement (typically a
      unicode string or an icon specification).
    - Use the variable =skyConditionS= to display the replacement of the
      corresponding sky condition. All other =Weather= template variables
      are available as well.

      For example:

      #+begin_src haskell
        WeatherX "LEBL"
                 [ ("clear", "🌣")
                 , ("sunny", "🌣")
                 , ("mostly clear", "🌤")
                 , ("mostly sunny", "🌤")
                 , ("partly sunny", "⛅")
                 , ("fair", "🌑")
                 , ("cloudy","☁")
                 , ("overcast","☁")
                 , ("partly cloudy", "⛅")
                 , ("mostly cloudy", "🌧")
                 , ("considerable cloudiness", "⛈")]
                 ["-t", "<fn=2><skyConditionS></fn> <tempC>° <rh>%  <windKmh> (<hour>)"
                 , "-L","10", "-H", "25", "--normal", "black"
                 , "--high", "lightgoldenrod4", "--low", "darkseagreen4"]
                 18000
      #+end_src

      As mentioned, the replacement string can also be an icon specification,
      such as =("clear", "<icon=weather-clear.xbm/>")=.

*** =UVMeter=

    - Aliases to "uv" + station id. For example: =%uv Brisbane%= or
      =%uv   Alice Springs%=

    - Args: default monitor arguments, plus:

      - =--useManager= /bool/ : Whether to use one single manager per
        monitor for managing network connections or create a new one every
        time a connection is made.

        - Short option: =-m=
        - Default: True

    - /Reminder:/ Keep the refresh rate high, to avoid making unnecessary
      requests every time the plug-in is run.

    - Station IDs can be found here:
      http://www.arpansa.gov.au/uvindex/realtime/xml/uvvalues.xml

    - Example:

      #+begin_src haskell
        Run UVMeter "Brisbane" ["-H", "3", "-L", "3", "--low", "green", "--high", "red"] 900
      #+end_src
** Other monitors
*** =CatInt n filename=

    - Reads and displays an integer from the file whose path is =filename=
      (especially useful with files in =/sys=).

    - Aliases as =catn= (e.g. =Cat 0= as =cat0=, etc.) so you can have
      several.

    - Example:

      #+begin_src haskell
        Run CatInt 0 "/sys/devices/platform/thinkpad_hwmon/fan1_input" [] 50
      #+end_src

*** =CommandReader "/path/to/program" Alias=

    - Runs the given program, and displays its standard output.

*** =Uptime Args RefreshRate=

    - Aliases to =uptime=
    - Args: default monitor arguments. The low and high thresholds refer to
      the number of days.
    - Variables that can be used with the =-t/--template= argument: =days=,
      =hours=, =minutes=, =seconds=. The total uptime is the sum of all
      those fields. You can set the =-S= argument to =True= to add units to
      the display of those numeric fields.
    - Default template: =Up: <days>d <hours>h <minutes>m=

* Interfacing with window managers
  :PROPERTIES:
  :CUSTOM_ID: interfacing-with-window-managers
  :END:
** Property-based logging
*** =XMonadLog=

    - Aliases to XMonadLog

    - Displays information from xmonad's =_XMONAD_LOG=. You can use
      this by using functions from the [[https://hackage.haskell.org/package/xmonad-contrib-0.16/docs/XMonad-Hooks-DynamicLog.html][XMonad.Hooks.DynamicLog]]
      module. By using the =xmonadPropLog= function in your logHook,
      you can write the the above property. The following shows a
      minimal xmonad configuration that spawns xmobar and then
      writes to the =_XMONAD_LOG= property.

      #+begin_src haskell
        main = do
          spawn "xmobar"
          xmonad $ def
            { logHook = dynamicLogString defaultPP >>= xmonadPropLog
            }
      #+end_src

      This plugin can be used as a sometimes more convenient
      alternative to =StdinReader=. For instance, it allows you to
      (re)start xmobar outside xmonad.

*** =UnsafeXMonadLog=

    - Aliases to UnsafeXMonadLog
    - Displays any text received by xmobar on the =_XMONAD_LOG= atom.
    - Will not do anything to the text received. This means you can pass
      xmobar dynamic actions. Be careful to escape (using =<raw=…>=) or
      remove tags from dynamic text that you pipe through to xmobar in this
      way.

    - Sample usage: Send the list of your workspaces, enclosed by actions
      tags, to xmobar.  This enables you to switch to a workspace when you
      click on it in xmobar!

      #+begin_src shell
        <action=`xdotool key alt+1`>ws1</action> <action=`xdotool key alt+1`>ws2</action>
      #+end_src

    - If you use xmonad, It is advised that you still use =xmobarStrip= for
      the =ppTitle= in your logHook:

      #+begin_src haskell
        myPP = defaultPP { ppTitle = xmobarStrip }
        main = xmonad $ def
          { logHook = dynamicLogString myPP >>= xmonadPropLog
          }
      #+end_src

*** =XPropertyLog PropName=

    - Aliases to =PropName=
    - Reads the X property named by =PropName= (a string) and displays its
      value. The [[../etc/xmonadpropwrite.hs][etc/xmonadpropwrite.hs script]] in xmobar's distribution can be
      used to set the given property from the output of any other program or
      script.

*** =UnsafeXPropertyLog PropName=

    - Aliases to =PropName=
    - Same as =XPropertyLog= but the input is not filtered to avoid
      injection of actions (cf. =UnsafeXMonadLog=). The program writing the
      value of the read property is responsible of performing any needed
      cleanups.

*** =NamedXPropertyLog PropName Alias=

    - Aliases to =Alias=
    - Same as =XPropertyLog= but a custom alias can be specified.

*** =UnsafeNamedXPropertyLog PropName Alias=

    - Aliases to =Alias=
    - Same as =UnsafeXPropertyLog=, but a custom alias can be specified.

** Logging via Stdin
*** =StdinReader=

    - Aliases to StdinReader
    - Displays any text received by xmobar on its standard input.
    - Strips actions from the text received. This means you can't pass
      dynamic actions via stdin. This is safer than =UnsafeStdinReader=
      because there is no need to escape the content before passing it to
      xmobar's standard input.

*** =UnsafeStdinReader=

    - Aliases to UnsafeStdinReader
    - Displays any text received by xmobar on its standard input.
    - Similar to [[=UnsafeXMonadLog=][UnsafeXMonadLog]], in the sense that it does not strip any
      actions from the received text, only using =stdin= and not a property
      atom of the root window. Please be equally carefully when using this
      as when using =UnsafeXMonadLog=!

** Pipe-based logging
*** =PipeReader "default text:/path/to/pipe" Alias=

    - Reads its displayed output from the given pipe.
    - Prefix an optional default text separated by a colon
    - Expands environment variables in the first argument of syntax =${VAR}=
      or =$VAR=

*** =MarqueePipeReader "default text:/path/to/pipe" (length, rate, sep) Alias=

    - Generally equivalent to PipeReader

    - Text is displayed as marquee with the specified length, rate in 10th
      seconds and separator when it wraps around

      #+begin_src haskell
        Run MarqueePipeReader "/tmp/testpipe" (10, 7, "+") "mpipe"
      #+end_src

    - Expands environment variables in the first argument

*** =BufferedPipeReader Alias [(Timeout, Bool, "/path/to/pipe1"), ..]=

    - Display data from multiple pipes.

    - Timeout (in tenth of seconds) is the value after which the
      previous content is restored i.e. if there was already
      something from a previous pipe it will be put on display
      again, overwriting the current status.

    - A pipe with Timeout of 0 will be displayed permanently, just
      like =PipeReader=

    - The boolean option indicates whether new data for this pipe
      should make xmobar appear (unhide, reveal). In this case, the
      Timeout additionally specifies when the window should be
      hidden again. The output is restored in any case.

    - Use it for OSD-like status bars e.g. for setting the volume or
      brightness:

      #+begin_src haskell
        Run BufferedPipeReader "bpr"
            [ (  0, False, "/tmp/xmobar_window"  )
            , ( 15,  True, "/tmp/xmobar_status"  )
            ]
      #+end_src

      Have your window manager send window titles to
      =/tmp/xmobar_window=.  They will always be shown and not reveal
      your xmobar. Sending some status information to
      =/tmp/xmobar_status= will reveal xmonad for 1.5 seconds and
      temporarily overwrite the window titles.

    - Take a look at [[../etc/status.sh][etc/status.sh]]

    - Expands environment variables for the pipe path

** Handle-based logging
*** =HandleReader Handle Alias=

    - Display data from a Haskell =Handle=

    - This plugin is only useful if you are running xmobar from another
      Haskell program like XMonad.

    - You can use =System.Process.createPipe= to create a pair of =read= &
      =write= Handles. Pass the =read= Handle to HandleReader and write your
      output to the =write= Handle:

      #+begin_src haskell
        (readHandle, writeHandle) <- createPipe
        xmobarProcess <- forkProcess $ xmobar myConfig
                { commands =
                    Run (HandleReader readHandle "handle") : commands myConfig
                }
        hPutStr writeHandle "Hello World"
      #+end_src


** Software Transactional Memory

    When invoking xmobar from other Haskell code it can be easier and more
    performant to use shared memory.  The following plugins leverage
    =Control.Concurrent.STM= to realize these gains for xmobar.

*** =QueueReader (TQueue a) (a -> String) String=

    - Display data from a Haskell =TQueue a=.

    - This plugin is only useful if you are running xmobar from another
      haskell program like xmonad.

    - You should make an =IO= safe =TQueue a= with
      =Control.Concurrent.STM.newTQueueIO=.  Write to it from the user
      code with =writeTQueue=, and read with =readTQueue=.  A common use
      is to overwite =ppOutput= from =XMonad.Hooks.DynamicLog= as shown
      below.

      #+begin_src haskell
        main :: IO ()
        main = do
          initThreads
          q <- STM.newTQueueIO @String
          bar <- forkOS $ xmobar myConf
            { commands = Run (QueueReader q id "XMonadLog") : commands myConf }
          xmonad $ def { logHook = logWorkspacesToQueue q }

        logWorkspacesToQueue :: STM.TQueue String -> X ()
        logWorkspacesToQueue q =
          dynamicLogWithPP def { ppOutput = STM.atomically . STM.writeTQueue q }
      #+end_src

      Note that xmonad uses blocking Xlib calls in its event loop and isn't
      normally compiled with
      [[https://downloads.haskell.org/~ghc/latest/docs/html/users_guide/using-concurrent.html][the threaded RTS]]
      so an xmobar thread running inside xmonad will suffer from delayed
      updates. It is thus necessary to enable =-threaded= when compiling
      xmonad configuration (=xmonad.hs=), e.g. by using a custom
      =~/.xmonad/build= script.



* 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 ProgramName Args Alias RefreshRate=

  - ProgramName: the name of the program
  - Args: the arguments to be passed to the program at execution time
  - RefreshRate: number of tenths of second between re-runs of the
    command. A zero or negative rate means that the command will be
    executed only once.
  - 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.

  E.g.:

  #+begin_src haskell
    Run Com "uname" ["-s","-r"] "" 0
  #+end_src

  can be used in the output template as =%uname%= (and xmobar will call
  /uname/ only once), while

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

  can be used in the output template as =%mydate%=.

  Sometimes, you don't mind if the command executed exits with an
  error, or you might want to display a custom message in that
  case. To that end, you can use the =ComX= variant:

  =ComX ProgramName Args ExitMessage Alias RefreshRate=

  Works like =Com=, but displaying =ExitMessage= (a string) if the
  execution fails. For instance:

  #+begin_src haskell
    Run ComX "date" ["+\"%a %b %_d %H:%M\""] "N/A" "mydate" 600
  #+end_src

  will display "N/A" if for some reason the =date= invocation fails.
