1UDEV_DEVICE_HAS_TAG(3)        udev_device_has_tag       UDEV_DEVICE_HAS_TAG(3)
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3
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NAME

6       udev_device_has_tag, udev_device_has_current_tag,
7       udev_device_get_devlinks_list_entry,
8       udev_device_get_properties_list_entry, udev_device_get_tags_list_entry,
9       udev_device_get_current_tags_list_entry,
10       udev_device_get_sysattr_list_entry, udev_device_get_property_value,
11       udev_device_get_sysattr_value, udev_device_set_sysattr_value - Retrieve
12       or set device attributes
13

SYNOPSIS

15       #include <libudev.h>
16
17       int udev_device_has_tag(struct udev_device *udev_device,
18                               const char *tag);
19
20       int udev_device_has_current_tag(struct udev_device *udev_device,
21                                       const char *tag);
22
23       struct udev_list_entry
24                                                                   *udev_device_get_devlinks_list_entry(struct udev_device *udev_device);
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26       struct udev_list_entry
27                                                                     *udev_device_get_properties_list_entry(struct udev_device *udev_device);
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29       struct udev_list_entry
30                                                               *udev_device_get_tags_list_entry(struct udev_device *udev_device);
31
32       struct udev_list_entry
33                                                                       *udev_device_get_current_tags_list_entry(struct udev_device *udev_device);
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35       struct udev_list_entry
36                                                                  *udev_device_get_sysattr_list_entry(struct udev_device *udev_device);
37
38       const char
39                                                  *udev_device_get_property_value(struct udev_device *udev_device,
40                                                  const char *key);
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42       const char
43                                                 *udev_device_get_sysattr_value(struct udev_device *udev_device,
44                                                 const char *sysattr);
45
46       int udev_device_set_sysattr_value(struct udev_device *udev_device,
47                                         const char *sysattr,
48                                         const char *value);
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DESCRIPTION

51       udev_device_has_tag() returns a valuer larger than zero if the
52       specified device object has the indicated tag assigned to it, and zero
53       otherwise. See udev(7) for details on the tags concept.
54       udev_device_has_current_tag() executes a similar check, however only
55       determines whether the indicated tag was set as result of the most
56       recent event seen for the device. Tags are "sticky", i.e. once set for
57       a device they remain on the device until the device is unplugged, even
58       if the rules run for later events of the same device do not set them
59       anymore. Any tag for which udev_device_has_current_tag() returns true
60       will hence also return true when passed to udev_device_has_tag(), but
61       the opposite might not be true, in case a tag is no longer configured
62       by the rules applied to the most recent device even.
63
64       udev_device_get_tags_list_entry() returns a udev_list_entry object,
65       encapsulating a list of tags set for the specified device. Similar,
66       udev_device_get_current_tags_list_entry() returns a list of tags set
67       for the specified device as effect of the most recent device event seen
68       (see above for details on the difference).
69

RETURN VALUE

71       On success, udev_device_has_tag() and udev_device_has_current_tag()
72       return positive or 0, depending on whether the device has the given tag
73       or not. On failure, a negative error code is returned.
74
75       On success, udev_device_get_devlinks_list_entry(),
76       udev_device_get_properties_list_entry(),
77       udev_device_get_tags_list_entry(),
78       udev_device_get_current_tags_list_entry() and
79       udev_device_get_sysattr_list_entry() return a pointer to the first
80       entry of the retrieved list. If that list is empty, or if an error
81       occurred, NULL is returned.
82
83       On success, udev_device_get_property_value() and
84       udev_device_get_sysattr_value() return a pointer to a constant string
85       of the requested value. On error, NULL is returned. Attributes that may
86       contain NUL bytes should not be retrieved with
87       udev_device_get_sysattr_value(); instead, read them directly from the
88       files within the device's syspath.
89
90       On success, udev_device_set_sysattr_value() returns an integer greater
91       than, or equal to, 0. On failure, a negative error code is returned.
92       Values that contain NUL bytes should not be set with this function;
93       instead, write them directly to the files within the device's syspath.
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SEE ALSO

96       udev(7), udev_new(3), udev_device_new_from_syspath(3),
97       udev_device_get_syspath(3), udev_enumerate_new(3),
98       udev_monitor_new_from_netlink(3), udev_list_entry(3), systemd(1),
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100
101
102systemd 248                                             UDEV_DEVICE_HAS_TAG(3)
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