Description¶

sd_device_get_syspath() returns the sysfs path of the specified device record, including the /sys prefix. Example: /sys/devices/virtual/tty/tty7

sd_device_get_devpath() returns the sysfs path of the specified device record, excluding the /sys prefix. Example: /devices/virtual/tty/tty7

sd_device_get_sysname() returns the sysfs name of the specified device record, i.e. the last component of the sysfs path. Example: "tty7" for the device /sys/devices/virtual/tty/tty7

sd_device_get_sysnum() returns the sysfs device number of the specified device record, i.e. the numeric suffix of the last component of the sysfs path. Example: "7" for the device /sys/devices/virtual/tty/tty7

sd_device_get_subsystem() returns the kernel subsystem of the specified device record. This is a short string fitting into a filename, and thus does not contain a slash and cannot be empty. Example: "tty", "block" or "net".

sd_device_get_driver_subsystem() returns the connected bus type of the devices loaded by the specified driver device record. For example, when "iwlwifi" driver device is specified, which is used by the wireless network interfaces connected to PCI bus, this function returns "pci". This function only succeeds when sd_device_get_subsystem() returns "drivers". Example: "pci", "i2c", or "hid".

sd_device_get_devtype() returns the device type of the specified device record, if the subsystem manages multiple types of devices. Example: for devices of the "block" subsystem this can be "disk" or "partition"

sd_device_get_devname() returns the device node path of the specified device record if the device has a device node. Example: for /sys/devices/virtual/tty/tty7 the string /dev/tty7 is typically returned.

sd_device_get_devnum() returns the device node major/minor (i.e. dev_t) of the specified device record if the device has a device node (i.e. the one returned by sd_device_get_devname()). For devices belonging to the "block" subsystem this refers to a block device node, in all other cases to a character device node. Example: for the /sys/devices/virtual/tty/tty7 device this typically returns the device number with major/minor "4:7".

sd_device_get_ifindex() returns the network interface index of the specified device record, if the device encapsulates a network interface device, i.e. belongs to the "net" subsystem. Example: the "lo" interface typically has interface index 1.

sd_device_get_driver() returns the kernel driver name attached to the device. Note that the driver field is set on the devices consumed by the driver, not on the device created by it. Example: a PCI device /sys/bus/pci/devices/0000:00:1f.6 might be attached to a driver "e1000e".

sd_device_get_diskseq() returns the kernel disk sequence number of the block device. This number monotonically increases whenever a backing medium of a block device changes without the device name changing, and is relevant for block devices encapsulating devices with changing media (e.g. floppy or CD-ROM), or loopback block devices. Only defined for block devices, i.e. those of subsystem "block".

sd_device_get_device_id() returns the short string that identifies the device record. When the device ID obtained by the function for a specified device record is passed to sd_device_new_from_device_id(), a new instance of the same device record will be gained. When a block or character device is specified, which has corresponding device node, this returns "b" or "c", respectively, followed by the device node major and minor numbers separated with a colon. Example: "b259:1" or "c10:121". When a network interface device is specified, this returns "n" followed by the interface index, which can be obtained by sd_device_get_ifindex(). Example: "n1". When a device in the "driver" subsystem is specified, this returns "+drivers:" followed by its driver subsystem and sysfs name separated with a colon. Example: "+drivers:pci:iwlwifi" for a driver device record whose driver subsystem is "pci" and sysfs name is "iwlwifi", When an other type of device is specified, this function returns "+" followed by its subsystem and sysfs name separated with a colon. Example: "+acpi:ACPI0003:00", "+input:input16", or "+pci:0000:00:1f.6".

Return Value¶

On success, these calls return 0 or a positive integer. On failure, they return a negative errno-style error code.

Notes¶

Functions described here are available as a shared library, which can be compiled against and linked to with the libsystemd pkg-config(1) file.

The code described here uses getenv(3), which is declared to be not multi-thread-safe. This means that the code calling the functions described here must not call setenv(3) from a parallel thread. It is recommended to only do calls to setenv() from an early phase of the program when no other threads have been started.

History¶

sd_device_get_syspath(), sd_device_get_devpath(), sd_device_get_sysname(), sd_device_get_sysnum(), sd_device_get_subsystem(), sd_device_get_devtype(), sd_device_get_devname(), sd_device_get_devnum(), sd_device_get_ifindex(), sd_device_get_driver(), and sd_device_get_diskseq() were added in version 251.

sd_device_get_driver_subsystem() and sd_device_get_device_id() were added in version 257.

See Also¶

systemd(1), sd-device(3)