Provided by: x11-utils_7.7+5_amd64 
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.
-version
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