XPROP(1) XPROP(1)
NAME
xprop - property displayer for X
SYNOPSIS
xprop [-help] [-grammar] [-id id] [-root] [-name name]
[-font font]
[-display display] [-len n] [-notype] [-fs file]
[-remove property-name] [-f name format [dformat]]
SUMMARY
The xprop utility displays 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.
When a reparenting window manager is running, such as
twm(1) or mwm(1), mouse selection of the target window
reports no information. You can execute xlswins(1) to
determine the window id and name of the target client
window, then use it as the argument to the -id or -name
options, respectively, of xwininfo.
OPTIONS
-help
print out a summary of command line options.
-grammar
print out detailed grammar for all command line
options.
-id id
allows the user to select window id on the command
line rather than using the pointer to select the
target window. This is 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
allows the user to specify that the window name is
the target window on the command line rather than
using the pointer to select the target window.
-font font
allows the user to specify that the properties of
font should be displayed.
-root
specifies that X's root window is the target window.
This is useful in situations where the root window is
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XPROP(1) XPROP(1)
completely obscured.
-display display
allows you to specify to which server to connect.
-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 should be used as a source of
more formats for properties.
-remove property-name
specifies the name of a property to be removed from
the indicated window.
-f name format [dformat]
specifies that the format for name should be format
and that the display format 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 as 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 hexadecimal (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, or
-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
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XPROP(1) XPROP(1)
opposed to a window, the -font argument must be used.
Other than the above four arguments, the -help argument
for obtaining help, and the -grammar argument for
listing the full grammar for the command line, all
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
contains two parts: a format and a dformat. format
specifies the actual formatting of the property (i.e.,
is it made up of words, bytes, or longs?) 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 because
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
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.)
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XPROP(1) XPROP(1)
A value of 8 means the property is a sequence of bytes,
while a value of 16 would mean the property is a
sequence of words. The difference between these two is
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., an
integer, a string, or an atom). 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. This type field
should be size 32.
b
The field is a 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.
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.
x
The field is a hexadecimal number (like c but
displayed in hexadecimal; 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.
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XPROP(1) XPROP(1)
The format of a dformat unlike that of a format is not
so rigid. The only limitations on a dformat is that
you cannot 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
display format 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 $, ?, \, or ( in a dformat
prints as itself. To print out one of $, ?, \, or (
precede it by \. For example, to print out $, 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 prints in decimal while if it is described by a
x it is displayed in hexadecimal.
If the field is not present in the property (this is
possible with some properties), <field not available>
is displayed instead. $n+, displays field number n,
then a comma, then field number n+1, then another
comma, then ... until the last field is 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) displays text if, and
only if, exp evaluates to nonzero. This is useful for
two things. First, it allows fields to be displayed
if, and only if, a flag is set. 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:
exp ::= term | term=exp | !exp
term ::= n | $n | mn
The ! operator is a logical not, changing 0 to 1 and
any nonzero 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
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XPROP(1) XPROP(1)
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; otherwise, 0.
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 display format 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
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XPROP(1) XPROP(1)
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
ENVIRONMENT
DISPLAY
to get default display.
XPROPFORMATS
specifies the name of a file from which additional
formats are to be obtained.
SPECIAL CONSIDERATION
If a reparenting window manager is running twm or mwm
(the Motif window manager), then the window information
provided does not refer to the client window selected,
but instead refers to the window manager itself, which
is immediately below the root window. If twm is
running, information is displayed about the frame
window not the client-created window. Because this
information may not be what is needed, it is preferable
to invoke xprop with the -id option.
SEE ALSO
xwininfo(1)
AUTHOR
Mark Lillibridge, MIT Project Athena
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