xprop
property displayer for X
see also :
X - xdpyinfo - xwininfo - xdriinfo - xvinfo
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] [-f atom format [dformat]]*
[format [dformat] atom]*
add an example, a script, a trick and tips
examples
source
echo `xprop -root WM_NAME | awk -F\" '{print $2}'`
To display the name of the root window: xprop -root
WM_NAME
To display the window manager hints for the clock: xprop
-name xclock WM_HINTS
To display the start of the cut buffer: xprop -root -len
100 CUT_BUFFER0
To display the point size of the fixed font: xprop -font
fixed POINT_SIZE
To display all the properties of window # 0x200007: xprop
-id 0x200007
To set a simple string property: xprop -root -format
MY_ATOM_NAME 8s -set MY_ATOM_NAME "my_value"
source
window="$(xprop -root
_NET_ACTIVE_WINDOW | awk '{print $5}')"
pid="$(xprop -id "$window" | awk '{print $3}')"
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.
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.
-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.
display
To get default display.
XPROPFORMATS
Specifies the name of a file from which additional formats are to
be obtained.
environment
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.
see also
X ,
xdpyinfo , xwininfo , xdriinfo , glxinfo,
xvinfo
author
Mark
Lillibridge, MIT Project Athena