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NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | EXAMPLES | HISTORY | SEE ALSO | COLOPHON |
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SD_DE...PARENT(3) sd_device_enumerator_add_match_parent SD_DE...PARENT(3)
sd_device_enumerator_add_match_parent,
sd_device_enumerator_add_match_property,
sd_device_enumerator_add_match_property_required,
sd_device_enumerator_add_match_subsystem,
sd_device_enumerator_add_match_sysattr,
sd_device_enumerator_add_match_sysname,
sd_device_enumerator_add_nomatch_sysname,
sd_device_enumerator_add_match_tag,
sd_device_enumerator_allow_uninitialized,
sd_device_enumerator_add_all_parents - Add a filter to the device
enumerator
#include <systemd/sd-device.h>
int
sd_device_enumerator_add_match_parent(sd_device_enumerator *enumerator,
sd_device *parent);
int
sd_device_enumerator_add_match_property(sd_device_enumerator *enumerator,
const char *property,
const char *value);
int
sd_device_enumerator_add_match_property_required(sd_device_enumerator *enumerator,
const char *property,
const char *value);
int
sd_device_enumerator_add_match_subsystem(sd_device_enumerator *enumerator,
const char *subsystem,
int match);
int
sd_device_enumerator_add_match_sysattr(sd_device_enumerator *enumerator,
const char *sysattr,
const char *value,
int match);
int
sd_device_enumerator_add_match_sysname(sd_device_enumerator *enumerator,
const char *sysname);
int
sd_device_enumerator_add_nomatch_sysname(sd_device_enumerator *enumerator,
const char *sysname);
int
sd_device_enumerator_add_match_tag(sd_device_enumerator *enumerator,
const char *tag);
int
sd_device_enumerator_allow_uninitialized(sd_device_enumerator *enumerator);
int
sd_device_enumerator_add_all_parents(sd_device_enumerator *enumerator);
The sd_device_enumerator_add_match_parent() function adds a filter
to the enumerator so that only devices under the tree of the
specified parent device are enumerated. If this is called multiple
times the previously set parent device is cleared and only the
last call takes an effect.
The sd_device_enumerator_add_match_property() function adds a
filter to the enumerator so that only devices with the specified
property equals to the value are enumerated. Both property and
value can be a glob pattern. When this is called multiple times,
devices that have at least one of the specified properties with
matching values are enumerated. That is, filters are ORed.
The sd_device_enumerator_add_match_property_required() function
adds a filter to the enumerator so that only devices with the
specified property equals to the value are enumerated. This
function is similar to sd_device_enumerator_add_match_property(),
but when this is called multiple times, devices that have all
specified properties with matching values are enumerated. That is,
filters are ANDed.
The sd_device_enumerator_add_match_subsystem() function adds a
filter to the enumerator so that all devices in the specified
subsystem, when match is true. When match is false, then all
devices except those in the specified subsystem are enumerated.
When called multiple times, positive filters are ORed, and
negative ones are ANDed.
The sd_device_enumerator_add_match_sysattr() function adds a
filter on the sysfs attribute sysattr matching value. value can
be a glob pattern. If value is NULL, devices that either have (if
match is true) or do not have (if match is false) the specified
sysattr are included, regardless of its value. That is, NULL is
mostly equivalent to "*". When this function is called multiple
times, only devices that match all specified sysattr filters are
enumerated. That is, these filters are ANDed.
The sd_device_enumerator_add_match_sysname() function adds a
filter so that only devices whose sysname equals to sysname are
enumerated. sysname can be a glob pattern. When called multiple
times, filters are ORed.
The sd_device_enumerator_add_nomatch_sysname() function adds a
filter so that devices whose sysname equals to sysname are
excluded from the enumeration. This is useful for excluding
specific devices from the enumeration process. When called
multiple times, features are ANDed.
The sd_device_enumerator_add_match_tag() function adds a filter so
that only devices tagged with tag are enumerated. When called
multiple times, filters are ORed.
The sd_device_enumerator_allow_uninitialized() function allows
devices that have not yet been initialized by udev to be included
in the enumeration.
The sd_device_enumerator_add_all_parents() function enumerates all
parent devices of the matching devices. This is useful for cases
where you want to include all parent devices in the enumeration,
such as when you are interested in the entire device tree leading
up to a specific device.
All functions return 0 or a positive integer on success, or a
negative errno-style error code on failure.
Errors
Returned errors may indicate the following problems:
-ENOMEM
Memory allocation failed.
-EINVAL
One of the arguments is invalid.
Example 1. Detect Removable USB Devices (Using Match and Exclude)
/* SPDX-License-Identifier: MIT-0 */
#include <stdbool.h>
#include <stdio.h>
#include <systemd/sd-device.h>
int main(void) {
__attribute__((cleanup(sd_device_enumerator_unrefp))) sd_device_enumerator *enumerator = NULL;
sd_device *device;
int r;
/* Create a new device enumerator */
r = sd_device_enumerator_new(&enumerator);
if (r < 0) {
fprintf(stderr, "Failed to create device enumerator: %s\n", strerror(-r));
return 1;
}
/* Include only devices from the "usb" subsystem */
r = sd_device_enumerator_add_match_subsystem(enumerator, "usb", true);
if (r < 0) {
fprintf(stderr, "Failed to add subsystem match: %s\n", strerror(-r));
return 1;
}
/*
* Exclude devices where the "removable" sysattr is "0"
* These are typically non-removable devices like built-in USB interfaces
*/
r = sd_device_enumerator_add_match_sysattr(enumerator, "removable", "0", false);
if (r < 0) {
fprintf(stderr, "Failed to add sysattr match: %s\n", strerror(-r));
return 1;
}
/* Begin enumerating matching devices */
for (device = sd_device_enumerator_get_device_first(enumerator);
device;
device = sd_device_enumerator_get_device_next(enumerator)) {
const char *syspath;
/* Get syspath for the device */
if (sd_device_get_syspath(device, &syspath) >= 0)
printf("Removable USB device found: %s\n", syspath);
}
return 0;
}
sd_device_enumerator_add_match_parent(),
sd_device_enumerator_add_match_property(),
sd_device_enumerator_add_match_subsystem(),
sd_device_enumerator_add_match_sysattr(),
sd_device_enumerator_add_match_sysname(),
sd_device_enumerator_add_match_tag(), and
sd_device_enumerator_allow_uninitialized() were added in version
240.
sd_device_enumerator_add_nomatch_sysname() was added in version
251.
sd_device_enumerator_add_match_property_required() was added in
version 255.
sd_device_enumerator_add_all_parents() was added in version 258.
sd_device_ref(3), sd_device_enumerator_new(3),
sd_device_enumerator_get_device_first(3)
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 SD_DE...PARENT(3)
Pages that refer to this page: sd_device_enumerator_get_device_first(3), sd_device_enumerator_new(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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