XPROP(1) User Commands XPROP(1)

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

X Version 11 xprop 1.2.7 XPROP(1)