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NAME

       xprop - property displayer for X

SYNOPSIS

       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] [-version] [-f atom format [dformat]]* [format [dformat] atom]*

SUMMARY

       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.

OPTIONS

       -help   Print out a summary of command line options.

       -grammar
               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 application.

       -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 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 property change events.

       -verson Print program version information and exit.

       -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.

DESCRIPTION

       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 printed.

       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
       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
       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 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  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 formats.

       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.

EXAMPLES

       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

       To display the start of the cut buffer: xprop -root -len 100 CUT_BUFFER0

       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"

ENVIRONMENT

       DISPLAY To get default display.

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

SEE ALSO

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

AUTHOR

       Mark Lillibridge, MIT Project Athena