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NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | HISTORY | SEE ALSO | COLOPHON |
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UDEV_DEVICE_HAS_TAG(3) udev_device_has_tag UDEV_DEVICE_HAS_TAG(3)
udev_device_has_tag, udev_device_has_current_tag,
udev_device_get_devlinks_list_entry,
udev_device_get_properties_list_entry,
udev_device_get_tags_list_entry,
udev_device_get_current_tags_list_entry,
udev_device_get_sysattr_list_entry,
udev_device_get_property_value, udev_device_get_sysattr_value,
udev_device_set_sysattr_value - Retrieve or set device attributes
#include <libudev.h>
int udev_device_has_tag(struct udev_device *udev_device,
const char *tag);
int udev_device_has_current_tag(struct udev_device *udev_device,
const char *tag);
struct udev_list_entry
*udev_device_get_devlinks_list_entry(struct udev_device *udev_device);
struct udev_list_entry
*udev_device_get_properties_list_entry(struct udev_device *udev_device);
struct udev_list_entry
*udev_device_get_tags_list_entry(struct udev_device *udev_device);
struct udev_list_entry
*udev_device_get_current_tags_list_entry(struct udev_device *udev_device);
struct udev_list_entry
*udev_device_get_sysattr_list_entry(struct udev_device *udev_device);
const char
*udev_device_get_property_value(struct udev_device *udev_device,
const char *key);
const char
*udev_device_get_sysattr_value(struct udev_device *udev_device,
const char *sysattr);
int udev_device_set_sysattr_value(struct udev_device *udev_device,
const char *sysattr,
const char *value);
udev_device_has_tag() returns a value larger than zero if the
specified device object has the indicated tag assigned to it, and
zero otherwise. See udev(7) for details on the tags concept.
udev_device_has_current_tag() executes a similar check, however
only determines whether the indicated tag was set as result of the
most recent event seen for the device. Tags are "sticky", i.e.
once set for a device they remain on the device until the device
is unplugged, even if the rules run for later events of the same
device do not set them anymore. Any tag for which
udev_device_has_current_tag() returns true will hence also return
true when passed to udev_device_has_tag(), but the opposite might
not be true, in case a tag is no longer configured by the rules
applied to the most recent device even.
udev_device_get_tags_list_entry() returns a udev_list_entry
object, encapsulating a list of tags set for the specified device.
Similar, udev_device_get_current_tags_list_entry() returns a list
of tags set for the specified device as effect of the most recent
device event seen (see above for details on the difference).
On success, udev_device_has_tag() and
udev_device_has_current_tag() return positive or 0, depending on
whether the device has the given tag or not. On failure, a
negative error code is returned.
On success, udev_device_get_devlinks_list_entry(),
udev_device_get_properties_list_entry(),
udev_device_get_tags_list_entry(),
udev_device_get_current_tags_list_entry() and
udev_device_get_sysattr_list_entry() return a pointer to the first
entry of the retrieved list. If that list is empty, or if an error
occurred, NULL is returned.
On success, udev_device_get_property_value() and
udev_device_get_sysattr_value() return a pointer to a constant
string of the requested value. On error, NULL is returned.
Attributes that may contain NUL bytes should not be retrieved with
udev_device_get_sysattr_value(); instead, read them directly from
the files within the device's syspath.
On success, udev_device_set_sysattr_value() returns an integer
greater than, or equal to, 0. On failure, a negative error code is
returned. Values that contain NUL bytes should not be set with
this function; instead, write them directly to the files within
the device's syspath.
udev_device_get_devlinks_list_entry(),
udev_device_get_properties_list_entry(),
udev_device_get_tags_list_entry(),
udev_device_get_sysattr_list_entry(),
udev_device_get_property_value(), udev_device_has_tag(),
udev_device_get_sysattr_value(), and
udev_device_set_sysattr_value() were added in version 221.
udev_device_has_current_tag() and
udev_device_get_current_tags_list_entry() were added in version
247.
udev(7), udev_new(3), udev_device_new_from_syspath(3),
udev_device_get_syspath(3), udev_enumerate_new(3),
udev_monitor_new_from_netlink(3), udev_list_entry(3), systemd(1)
This page is part of the systemd (systemd system and service
manager) project. Information about the project can be found at
⟨http://www.freedesktop.org/wiki/Software/systemd⟩. If you have a
bug report for this manual page, see
⟨http://www.freedesktop.org/wiki/Software/systemd/#bugreports⟩.
This page was obtained from the project's upstream Git repository
⟨https://github.com/systemd/systemd.git⟩ on 2025-08-11. (At that
time, the date of the most recent commit that was found in the
repository was 2025-08-11.) If you discover any rendering
problems in this HTML version of the page, or you believe there is
a better or more up-to-date source for the page, or you have
corrections or improvements to the information in this COLOPHON
(which is not part of the original manual page), send a mail to
man-pages@man7.org
systemd 258~rc2 UDEV_DEVICE_HAS_TAG(3)
Pages that refer to this page: udev_device_get_syspath(3), udev_device_new_from_syspath(3), systemd.directives(7), systemd.index(7)
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HTML rendering created 2025-09-06 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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