xprop - property displayer for X


   xprop  [-help] [-grammar] [-id id] [-root] [-name name] [-frame] [-font
   font]  [-display  display]  [-len  n]  [-notype]  [-fs  file]  [-remove
   property-name]  [-set  property-name  value]  [-spy]  [-f  atom  format
   [dformat]]* [format [dformat] atom]*


   The xprop utility is for displaying window and font properties in an  X
   server.   One  window  or  font  is  selected  using  the  command line
   arguments or possibly in the case of  a  window,  by  clicking  on  the
   desired  window.   A  list  of  properties is then given, possibly with
   formatting information.


   -help   Print out a summary of command line options.

           Print out a detailed grammar for all command line options.

   -id id  This argument allows the  user  to  select  window  id  on  the
           command line rather than using the pointer to select the target
           window.  This is very useful in debugging X applications  where
           the  target window is not mapped to the screen or where the use
           of the pointer  might  be  impossible  or  interfere  with  the

   -name name
           This  argument allows the user to specify that the window named
           name is the target window on the command line rather than using
           the pointer to select the target window.

   -font font
           This argument allows the user to specify that the properties of
           font font should be displayed.

   -root   This argument specifies that X's  root  window  is  the  target
           window.   This is useful in situations where the root window is
           completely obscured.

   -display display
           This argument allows you to specify the server to  connect  to;
           see X(7).

   -len n  Specifies  that  at most n bytes of any property should be read
           or displayed.

   -notype Specifies  that  the  type  of  each  property  should  not  be

   -fs file
           Specifies  that  file  file  should be used as a source of more
           formats for properties.

   -frame  Specifies that when selecting a window by hand (i.e. if none of
           -name,  -root,  or  -id  are given), look at the window manager
           frame (if any) instead of looking for the client window.

   -remove property-name
           Specifies the name  of  a  property  to  be  removed  from  the
           indicated window.

   -set property-name value
           Specifies  the  name  of a property and a property value, to be
           set on the indicated window.

   -spy    Examine window properties forever, looking for property  change

   -f name format [dformat]
           Specifies  that  the  format for name should be format and that
           the dformat for name should be dformat.  If dformat is missing,
           " = $0+\n" is assumed.


   For  each of these properties, its value on the selected window or font
   is printed using the supplied formatting information  if  any.   If  no
   formatting  information  is supplied, internal defaults are used.  If a
   property is not defined on the selected window or font,  "not  defined"
   is  printed  as  the  value  for that property.  If no property list is
   given, all the properties possessed by the selected window or font  are

   A  window  may  be selected in one of four ways.  First, if the desired
   window is the root window, the -root argument  may  be  used.   If  the
   desired  window  is not the root window, it may be selected in two ways
   on the command line, either by id number such as might be obtained from
   xwininfo,  or by name if the window possesses a name.  The -id argument
   selects a window by id number in either decimal or hex (must start with
   0x) while the -name argument selects a window by name.

   The  last  way  to select a window does not involve the command line at
   all.  If none  of  -font,  -id,  -name,  and  -root  are  specified,  a
   crosshairs  cursor  is  displayed and the user is allowed to choose any
   visible window by pressing any pointer button in  the  desired  window.
   If  it  is  desired  to  display  properties  of a font as opposed to a
   window, the -font argument must be used.

   Other than  the  above  four  arguments  and  the  -help  argument  for
   obtaining  help, and the -grammar argument for listing the full grammar
   for the command line, all the other command line arguments are used  in
   specifying both the format of the properties to be displayed and how to
   display them.  The -len n argument specifies that at most  n  bytes  of
   any  given  property  will  be  read and displayed.  This is useful for
   example when displaying the cut buffer on the root window  which  could
   run to several pages if displayed in full.

   Normally each property name is displayed by printing first the property
   name then its type (if it has  one)  in  parentheses  followed  by  its
   value.   The  -notype argument specifies that property types should not
   be displayed.  The -fs argument is used to specify a file containing  a
   list of formats for properties while the -f argument is used to specify
   the format for one property.

   The formatting information for a  property  actually  consists  of  two
   parts,  a  format  and  a  dformat.   The  format  specifies the actual
   formatting of the property (i.e., is it made up  of  words,  bytes,  or
   longs?,  etc.)  while  the dformat specifies how the property should be

   The  following  paragraphs  describe  how  to  construct  formats   and
   dformats.   However,  for  the  vast  majority  of users and uses, this
   should not be necessary as the built in defaults  contain  the  formats
   and  dformats  necessary  to  display  all the standard properties.  It
   should only be necessary to specify  formats  and  dformats  if  a  new
   property  is being dealt with or the user dislikes the standard display
   format.  New users especially are encouraged to skip this part.

   A format consists of one of 0, 8, 16, or 32 followed by a  sequence  of
   one  or more format characters.  The 0, 8, 16, or 32 specifies how many
   bits per field there are in the  property.   Zero  is  a  special  case
   meaning  use  the  field  size information associated with the property
   itself.  (This is only needed for special cases like type INTEGER which
   is  actually  three different types depending on the size of the fields
   of the property.)

   A value of 8 means that the property is a sequence  of  bytes  while  a
   value  of  16 would mean that the property is a sequence of words.  The
   difference between these two lies in the  fact  that  the  sequence  of
   words will be byte swapped while the sequence of bytes will not be when
   read by a machine of the  opposite  byte  order  of  the  machine  that
   originally  wrote the property.  For more information on how properties
   are formatted and stored, consult the Xlib manual.

   Once the size of the fields has been  specified,  it  is  necessary  to
   specify  the  type  of each field (i.e., is it an integer, a string, an
   atom, or what?)  This is done using one format character per field.  If
   there  are more fields in the property than format characters supplied,
   the last character will be repeated as many times as necessary for  the
   extra fields.  The format characters and their meaning are as follows:

   a      The  field holds an atom number.  A field of this type should be
          of size 32.

   b      The field is an boolean.  A 0 means false  while  anything  else
          means true.

   c      The field is an unsigned number, a cardinal.

   i      The field is a signed integer.

   m      The field is a set of bit flags, 1 meaning on.

   o      The  field  is an array of icons, packed as a sequence of 32 bit
          numbers consisting of the width, height and ARGB  pixel  values,
          as  defined for the _NET_WM_ICON property in the Extended Window
          Manager Hints specification.   A field of this type must  be  of
          size 32.

   s      This  field and the next ones until either a 0 or the end of the
          property represent a sequence of bytes.  This  format  character
          is  only usable with a field size of 8 and is most often used to
          represent a string.

   t      This field and the next ones until either a 0 or the end of  the
          property represent an internationalized text string. This format
          character is only usable with a field size of 8. The  string  is
          assumed to be in an ICCCM compliant encoding and is converted to
          the current locale encoding before being output.

   u      This field and the next ones until either a 0 or the end of  the
          property  represent an UTF-8 encoded unicode string. This format
          character is only usable with a field size of 8. If  the  string
          is  found  to  be  an  invalid  character,  the type of encoding
          violation is printed instead, followed by the  string  formatted
          using  's'.  When  in  an  environment not capable of displaying
          UTF-8 encoded string, behaviour is identical to 's'.

   x      The field is a hex number (like 'c' but displayed in hex -  most
          useful for displaying window ids and the like)

   An  example format is 32ica which is the format for a property of three
   fields of 32 bits each, the first holding a signed integer, the  second
   an unsigned integer, and the third an atom.

   The  format  of a dformat unlike that of a format is not so rigid.  The
   only limitations on a dformat is that one may not start with  a  letter
   or  a  dash.   This  is so that it can be distinguished from a property
   name or an argument.  A dformat is a  text  string  containing  special
   characters instructing that various fields be printed at various points
   in a manner similar to the  formatting  string  used  by  printf.   For
   example,  the  dformat " is ( $0, $1 \)\n" would render the POINT 3, -4
   which has a format of 32ii as " is ( 3, -4 )\n".

   Any character other than a $, ?, \, or a  (  in  a  dformat  prints  as
   itself.   To  print  out  one  of $, ?, \, or ( precede it by a \.  For
   example, to print out a $, use \$.  Several special backslash sequences
   are  provided  as  shortcuts.   \n will cause a newline to be displayed
   while \t will cause a tab to be displayed.  \o  where  o  is  an  octal
   number will display character number o.

   A  $ followed by a number n causes field number n to be displayed.  The
   format of the displayed field depends on the formatting character  used
   to  describe  it  in  the corresponding format.  I.e., if a cardinal is
   described by 'c' it will print in decimal while if it is described by a
   'x' it is displayed in hex.

   If the field is not present in the property (this is possible with some
   properties), <field not available>  is  displayed  instead.   $n+  will
   display  field number n then a comma then field number n+1 then another
   comma then ... until the  last  field  defined.   If  field  n  is  not
   defined, nothing is displayed.  This is useful for a property that is a
   list of values.

   A ? is used to start  a  conditional  expression,  a  kind  of  if-then
   statement.   ?exp(text)  will display text if and only if exp evaluates
   to non-zero.  This is useful for two things.  First, it  allows  fields
   to  be displayed if and only if a flag is set.  And second, it allows a
   value such as a state number to be displayed as a name rather  than  as
   just a number.  The syntax of exp is as follows:

   exp    ::= term | term=exp | !exp

   term   ::= n | $n | mn

   The  !  operator is a logical ``not'', changing 0 to 1 and any non-zero
   value to 0.  = is an  equality  operator.   Note  that  internally  all
   expressions  are  evaluated  as  32  bit  numbers so -1 is not equal to
   65535.  = returns 1 if the two values  are  equal  and  0  if  not.   n
   represents  the constant value n while $n represents the value of field
   number n.  mn is 1 if flag number n in the first  field  having  format
   character 'm' in the corresponding format is 1, 0 otherwise.

   Examples:  ?m3(count:  $3\n)  displays field 3 with a label of count if
   and  only  if  flag  number   3   (count   starts   at   0!)   is   on.
   ?$2=0(True)?!$2=0(False)  displays  the  inverted value of field 2 as a

   In order to display a  property,  xprop  needs  both  a  format  and  a
   dformat.  Before xprop uses its default values of a format of 32x and a
   dformat of " = { $0+ }\n", it searches several places in an attempt  to
   find  more specific formats.  First, a search is made using the name of
   the property.  If this fails, a search is made using the  type  of  the
   property.   This  allows  type  STRING  to  be  defined with one set of
   formats while allowing property WM_NAME which is of type STRING  to  be
   defined  with a different format.  In this way, the display formats for
   a given type can be overridden for specific properties.

   The locations searched are in order: the format if any  specified  with
   the property name (as in 8x WM_NAME), the formats defined by -f options
   in last to first order, the contents of the file specified by  the  -fs
   option  if any, the contents of the file specified by the environmental
   variable XPROPFORMATS if any, and finally  xprop's  built  in  file  of

   The  format  of  the  files  referred  to  by  the -fs argument and the
   XPROPFORMATS variable is one or more lines of the following form:

   name format [dformat]

   Where name is either the name of a property or  the  name  of  a  type,
   format is the format to be used with name and dformat is the dformat to
   be used with name.  If dformat is not present, " = $0+\n" is assumed.


   To display the name of the root window: xprop -root WM_NAME

   To display the window manager hints for the clock: xprop  -name  xclock

   To  display  the  start  of  the  cut  buffer:  xprop  -root  -len  100

   To display the  point  size  of  the  fixed  font:  xprop  -font  fixed

   To display all the properties of window # 0x200007: xprop -id 0x200007

   To  set  a  simple string property: xprop -root -format MY_ATOM_NAME 8s
   -set MY_ATOM_NAME  "my_value"


   DISPLAY To get default display.

           Specifies the name of a file from which additional formats  are
           to be obtained.


   X(7), xdpyinfo(1), xwininfo(1), xdriinfo(1), glxinfo(1), xvinfo(1)


   Mark Lillibridge, MIT Project Athena


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