man pages section 1: User Commands

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Updated: July 2014

xprop (1)


xprop - property displayer for X


/usr/bin/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]*


User Commands                                            XPROP(1)

     xprop - property displayer for X

     /usr/bin/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 proper-
     ties in an X server.  One window or font is  selected  using
     the command line arguments or possibly in the case of a win-
     dow, by clicking on the desired window.  A list  of  proper-
     ties 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

     -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 com-
             mand 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(5).

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

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User Commands                                            XPROP(1)

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

     -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 prop-
             erty change events.

     -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 win-
     dow  or font is printed using the supplied formatting infor-
     mation 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

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User Commands                                            XPROP(1)

     properties of a font as opposed to a window, the -font argu-
     ment 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 parenthe-
     ses  followed  by its value.  The -notype argument specifies
     that property types should not be displayed.  The -fs  argu-
     ment  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  speci-
     fies how the property should be displayed.

     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  prop-
     erty.   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 orig-
     inally  wrote  the  property.   For  more information on how

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User Commands                                            XPROP(1)

     properties are formatted and stored, consult the  Xlib  man-

     Once the size of the fields has been specified, it is neces-
     sary to specify the type of each field (i.e., is it an inte-
     ger,  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 fol-

     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 any-
          thing 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 cur-
          rent 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

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User Commands                                            XPROP(1)

          hex - most useful for displaying  window  ids  and  the

     An  example  format is 32ica which is the format for a prop-
     erty 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

     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 dis-
     played.  The format of the displayed field  depends  on  the
     formatting  character used to describe it in the correspond-
     ing 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  possi-
     ble  with  some  properties),  <field not available> is dis-
     played 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 num-
     ber.  The syntax of exp is as follows:

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

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User Commands                                            XPROP(1)

     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 boolean.

     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  for-
     mats 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 spe-
     cific properties.

     The locations searched are in order: the format if any spec-
     ified 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  XPROP-
     FORMATS  if  any,  and finally xprop's built in file of for-

     The format of the files referred to by the -fs argument  and
     the  XPROPFORMATS  variable is one or more lines of the fol-
     lowing 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 WM_HINTS

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User Commands                                            XPROP(1)

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

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

     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(5),  xdpyinfo(1),  xwininfo(1),  xdriinfo(1),  glxinfo(1),

     Mark Lillibridge, MIT Project Athena

     See  attributes(5)  for  descriptions   of   the   following

     |      ATTRIBUTE TYPE         |      ATTRIBUTE VALUE        |
     |Availability                 |x11/x11-server-utilities     |
     |Interface Stability          |Committed                    |

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