udev / block-character dev
udev - это демон, который отвечает за виртуальную файловую систему /dev.
/etc/udev/ - каталог настроек демона.
/etc/udev/rules.d/ - каталог с правилами, по которым udev создаёт файлы устройств в /dev.
70-persistent-net.rules - правило для создания сетевых интерфейсов.
- (Hardware linux, nic) В общем случае если NIC есть в списке lspci, но отсутствует в ip a/ifconfig, а точнее ему не присвоено имя сервисом udev путем создания файла в директории /dev/ (осуществляется по ID устройства) – она не привязана к ядру, возможные причины:
- драйвер неизвестен
- девайс находится в userspace (dpdk)
- девайс находится в выделенном netns
ls -ltr /etc/udev/ total 12 -rw-r--r-- 1 root root 281 Feb 14 2019 udev.conf
Для необходимости изменения названия (что в целом не рекомендуется) в сравнении с выдаваемым udev по умолчанию нужно использовать rules или глобальный конфиг udev.conf (менее желательно). Так же когда есть конфликт с названиями интерфейсов в Linux может помочь заглянуть в файл /etc/udev/rules.d/70-persistent-net.rules
/etc/udev/rules.d/70-persistent-net.rules
Он может пригодиться при миграции с одной системы (с одним неймингом) на другую (с другим неймингом), при выходе из строя сетевой карты и желании сохранить номер старой, когда сетевые интерфейсы которые должны подняться, по какой-то причине не поднимаются…
Есть блочные и символные устройства:
Each piece of hardware in the system has an associated file used by the kernel to communicate with it. This type of file is called a device file. There are two types of device files: a character (or raw) device file and a block device file. The first character in each line entry tells if the file type is block or character. Ab denotes a block device file and a c represents a character device file. [root@host1 ~]# ll /dev/sd* brw-rw----. 1 root disk 8, 0 Aug 4 14:13 /dev/sda brw-rw----. 1 root disk 8, 1 Aug 4 14:13 /dev/sda1 brw-rw----. 1 root disk 8, 2 Aug 4 14:13 /dev/sda2 [root@host1 ~]# ll /dev/usb* crw-------. 1 root root 250, 0 Aug 4 14:13 /dev/usbmon0 crw-------. 1 root root 250, 1 Aug 4 14:13 /dev/usbmon1 crw-------. 1 root root 250, 2 Aug 4 14:13 /dev/usbmon2 [root@host1 ~]# file /dev/sda /dev/sda: block special [root@host1 ~]# file /dev/usbmon0 /dev/usbmon0: character special
uname
uname –a – смотрим тип ОС, hostname, версию ядра, разрядность (x86_64 indicates a running 64-bit kernel. If you use see i386, i486, i586 or i686, you’re running a 32-bit kernel). По отдельным опциям –s (kernel name), –n (node name), –r (kernel release), –v (kernel build date), –m (hardware name), –p (processor type), –i (hardware platform), and –o (OS name) можно посмотреть specific info.
# uname –a Linux host1.example.com 3.10.0-123.el7.x86_64 #1 SMP Mon May 5 11:16:57 EDT 2014 x86_64 x86_64 x86_64 GNU/Linux The information returned by the second command is: Linux Kernel name host1.example.com Hostname of this system 3.10.0-123.el7.x86_64 Kernel release #1 SMP Mon May 5 11:16:57 EDT 2014 Date and time of this kernel built x86_64 Machine hardware name x86_64 Processor type x86_64 Hardware platform GNU/Linux Operating system name
lspci
lspci – команда для просмотра устройств включенных от PCI bus (и не только – CPU, Ethernet, Wi-Fi, VGA, PCI, USB, AUDIO, etc). Фактическое устройство по факту может отличаться от того, которое отражено в названии lspci! (напр. Intel Core i7 вместо XEON или вместе – PCI bridge: Intel Corporation Xeon E7 v3/Xeon E5 v3/Core i7 PCI). Имя отображается в соответствии с установленным драйвером. Наиболее корректно для идентификации устройства использовать ID (по аналогии и с Windows).
The lspci command displays information about PCI buses and the devices attached to them.
Детальную информацию можно посмотреть добавив опции -v (verbose), -vv
redkin_p@testsmsrobot:~$ lspci
00:00.0 Host bridge: Intel Corporation 440BX/ZX/DX - 82443BX/ZX/DX Host bridge (rev 01)
00:01.0 PCI bridge: Intel Corporation 440BX/ZX/DX - 82443BX/ZX/DX AGP bridge (rev 01)
00:07.0 ISA bridge: Intel Corporation 82371AB/EB/MB PIIX4 ISA (rev 08)
00:07.1 IDE interface: Intel Corporation 82371AB/EB/MB PIIX4 IDE (rev 01)
00:07.3 Bridge: Intel Corporation 82371AB/EB/MB PIIX4 ACPI (rev 08)
00:07.7 System peripheral: VMware Virtual Machine Communication Interface (rev 10)
00:0f.0 VGA compatible controller: VMware SVGA II Adapter
00:15.0 PCI bridge: VMware PCI Express Root Port (rev 01)
00:15.1 PCI bridge: VMware PCI Express Root Port (rev 01)
00:15.2 PCI bridge: VMware PCI Express Root Port (rev 01)
03:00.0 Serial Attached SCSI controller: LSI Logic / Symbios Logic SAS1068 PCI-X Fusion-MPT SAS (rev 01)
0b:00.0 Ethernet controller: VMware VMXNET3 Ethernet Controller (rev 01)
13:00.0 Ethernet controller: VMware VMXNET3 Ethernet Controller (rev 01)
redkin.p@govnoserver:~$ lspci | grep VGA
00:02.0 VGA compatible controller: InnoTek Systemberatung GmbH VirtualBox Graphics Adapter
[user1@host1 ~]$ lspci | grep VGA 00:02.0 VGA compatible controller: Intel Corporation Core Processor Integrated Graphics Controller (rev 18) 01:00.0 VGA compatible controller: NVIDIA Corporation GT218M [GeForce 310M] (rev a2)
lsusb
lsusb – инфа о устройствах, подключенных к USB bus. Детальную информацию можно посмотреть добавив опции -v (verbose), -vv.
[user1@host1 ~]$ lsusb Bus 001 Device 002: ID 8087:0020 Intel Corp. Integrated Rate Matching Hub Bus 002 Device 002: ID 8087:0020 Intel Corp. Integrated Rate Matching Hub Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub Bus 002 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub Bus 001 Device 003: ID 064e:a136 Suyin Corp. Asus Integrated Webcam [CN031B] Bus 001 Device 004: ID 0b05:1788 ASUSTek Computer, Inc. BT-270 Bluetooth Adapter Bus 002 Device 003: ID 058f:6387 Alcor Micro Corp. Flash Drive Bus 002 Device 004: ID 0458:003a KYE Systems Corp. (Mouse Systems) NetScroll+ Mini Traveler / Genius NetScroll 120
What information can the lspci command display about the system hardware? (Choose THREE correct answers.)
A. Device IRQ settings
B. PCI bus speed
C. System battery type
D. Device vendor identification
E. Ethernet MAC address
Answer: ABD https://superuser.com/questions/693964/can-i-find-out-if-pci-e-slot-is-1-0-2-0-or-3-0-in-linux-terminal https://stackoverflow.com/questions/59010671/how-to-get-vendor-id-and-device-id-of-all-pci-devices lspci -vvvvnn 00:0f.0 VGA compatible controller [0300]: VMware SVGA II Adapter [15ad:0405] (prog-if 00 [VGA controller]) Subsystem: VMware SVGA II Adapter Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B- DisINTx- Status: Cap+ 66MHz- UDF- FastB2B+ ParErr- DEVSEL=medium >TAbort- <TAbort- <MAbort- >SERR- <PERR- INTx- Latency: 64, Cache Line Size: 32 bytes Interrupt: pin A routed to IRQ 16 Region 0: I/O ports at 1070 [size=16] Region 1: Memory at ec000000 (32-bit, prefetchable) [size=64M] Region 2: Memory at fe000000 (32-bit, non-prefetchable) [size=8M] [virtual] Expansion ROM at 000c0000 [disabled] [size=128K] Capabilities: [40] Vendor Specific Information: Len=00 <?> Kernel driver in use: vmwgfx Kernel modules: vmwgfx 00:15.6 PCI bridge [0604]: VMware PCI Express Root Port [15ad:07a0] (rev 01) (prog-if 00 [Normal decode]) LnkCap: Port #0, Speed 5GT/s, Width x32, ASPM L0s, Exit Latency L0s <64ns, L1 <1us ClockPM- Surprise- LLActRep+ BwNot- ASPMOptComp- LnkCtl: ASPM Disabled; RCB 64 bytes Disabled- CommClk- ExtSynch- ClockPM- AutWidDis- BWInt- AutBWInt- LnkSta: Speed 5GT/s, Width x32, TrErr- Train- SlotClk- DLActive- BWMgmt- ABWMgmt-
lscpu
lscpu – инфа о CPU.
[user1@host1 ~]$ lscpu Architecture: x86_64 CPU op-mode(s): 32-bit, 64-bit Byte Order: Little Endian CPU(s): 4 On-line CPU(s) list: 0-3 Thread(s) per core: 2 Core(s) per socket: 2 Socket(s): 1 NUMA node(s): 1 Vendor ID: GenuineIntel CPU family: 6 Model: 37 Model name: Intel(R) Core(TM) i3 CPU M 370 @ 2.40GHz Stepping: 5 CPU MHz: 933.000 BogoMIPS: 4932.50 Virtualization: VT-x L1d cache: 32K L1i cache: 32K L2 cache: 256K L3 cache: 3072K NUMA node0 CPU(s): 0-3 redkin_p@devastator ~ $ lscpu Architecture: x86_64 CPU op-mode(s): 32-bit, 64-bit Byte Order: Little Endian CPU(s): 8 On-line CPU(s) list: 0-7 Thread(s) per core: 2 Core(s) per socket: 2 Socket(s): 2 Vendor ID: GenuineIntel CPU family: 15 Model: 6 Model name: Intel(R) Xeon(TM) CPU 3.00GHz Stepping: 4 CPU MHz: 2999.679 BogoMIPS: 6000.26 Virtualization: VT-x L1d cache: 16K L2 cache: 2048K
sensors
sudo yum install lm_sensors.x86_64 – Ставим сенсоры
sudo sensors-detect – Далее рекомендуется настроить, при этом выбирать дефолты (они большими буквами)
sensors – Смотрим датчики. Например,
acpitz-virtual-0 – один из сенсоров CPU, в интернетах рекомендуют на него не обращать внимания
nouveau – видеокарта
coretemp – CPU
[user1@host1 ~]$ sensors acpitz-virtual-0 Adapter: Virtual device temp1: +57.0°C (crit = +108.0°C) nouveau-pci-0100 Adapter: PCI adapter temp1: +57.0°C (high = +95.0°C, hyst = +3.0°C) (crit = +105.0°C, hyst = +5.0°C) (emerg = +135.0°C, hyst = +5.0°C) coretemp-isa-0000 Adapter: ISA adapter Core 0: +51.0°C (high = +95.0°C, crit = +105.0°C) Core 2: +46.0°C (high = +95.0°C, crit = +105.0°C)
modules / drivers
Модули ядра в случае с hardware реализуют функционал драйверов этих устройств, хотя в целом модуль далеко не всегда есть драйвер.
Lsmod
Lsmod – Listing (Loaded) Modules, алтернатива просмотр содержимого /proc/modules
Linux provides the lsmod command to view currently loaded modules. Alternatively, you can view them by displaying the contents of the /proc/modules file. Both show module names, memory they are consuming, the number of processes using this and any dependent modules, and a list of dependent modules (if any).
# lsmod | head -n 5 Module Size Used by joydev 24576 0 hid_generic 16384 0 usbhid 57344 0 hid 139264 2 usbhid,hid_generic # cat /proc/modules | head -5 joydev 24576 0 - Live 0xffffffffc052c000 hid_generic 16384 0 - Live 0xffffffffc0560000 usbhid 57344 0 - Live 0xffffffffc082a000 hid 139264 2 hid_generic,usbhid, Live 0xffffffffc0501000 igb_uio 16384 0 - Live 0xffffffffc0492000 (OE)
modinfo
Modinfo – Displaying Module Information
The modinfo command can be used to display details about a module. The output shows the module file name, license type, author name, a short description, dependent module names, and other information. For instance, the following example shows information about a disk mirroring module called dm_mirror: ~# modinfo dm_mirror filename: /lib/modules/4.19.0-20-amd64/kernel/drivers/md/dm-mirror.ko license: GPL author: Joe Thornber description: device-mapper mirror target depends: dm-region-hash,dm-mod,dm-log retpoline: Y intree: Y name: dm_mirror vermagic: 4.19.0-20-amd64 SMP mod_unload modversions sig_id: PKCS#7 signer: Debian Secure Boot CA sig_key: 4B:6E:F5:AB:CA:66:98:25:17:8E:05:2C:84:66:7C:CB:C0:53:1F:8C sig_hashalgo: sha256 signature: 38:6E:54:9B:40:8A:98:B0:60:FC:53:49:FE:8C:FC:18:A5:22:FB:BA parm: raid1_resync_throttle:A percentage of time allocated for raid resynchronization (uint)
# modinfo ip_tables filename: /lib/modules/4.19.0-20-amd64/kernel/net/ipv4/netfilter/ip_tables.ko alias: ipt_icmp description: IPv4 packet filter author: Netfilter Core Team <coreteam@netfilter.org> license: GPL depends: x_tables retpoline: Y intree: Y name: ip_tables vermagic: 4.19.0-20-amd64 SMP mod_unload modversions sig_id: PKCS#7 signer: Debian Secure Boot CA sig_key: 4B:6E:F5:AB:CA:66:98:25:17:8E:05:2C:84:66:7C:CB:C0:53:1F:8C sig_hashalgo: sha256 signature: 2A:D0:2F:49:E3:38:E1:4C:7E:F7:91:33:4E:84:4C:CD:19:2E:28:45:
modprobe / insmod/ rmmod
modprobe (-r to unload, -v to debug) – Loading and Unloading Modules including dependent modules (для игнорирования зависимостей используются insmod, rmmod).
- Modprobe работает по умолчанию в системе – обнаруживает новый hardware и активирует модули для этого hardware в ядро
- Отключение модулей может быть полезно для безопасности – bluetooth, wifi, usb и проч. В том числе с добавлением запрета модуля по имени в автозагрузку за счет спального blacklist списка – /etc/modprobe.d/blacklist*
Execute the modprobe command to load a module dynamically into memory. This command ensures that any dependent modules are also loaded prior to the specified module. To unload the dm_mirror module along with all unused dependent modules, run the modprobe command with the –r option. [root@localhost ~]# modprobe -v dm_mirror insmod /lib/modules/3.10.0-327.36.2.el7.x86_64/kernel/drivers/md/dm-log.ko insmod /lib/modules/3.10.0-327.36.2.el7.x86_64/kernel/drivers/md/dm-region-hash.ko insmod /lib/modules/3.10.0-327.36.2.el7.x86_64/kernel/drivers/md/dm-mirror.ko [root@localhost ~]# modprobe -vr dm_mirror rmmod dm_mirror rmmod dm_region_hash rmmod dm_log
depmod
Depmod (-v debug) – Installing New Modules
Linux detects hardware devices and loads appropriate modules automatically; however, there may be instances when a device is left undetected or added online (as in the case of SAN disk allocation). In such a situation, execute the depmod command to force the system to scan the hardware, find appropriate modules for the new devices, create required module dependencies, and update the /lib/modules/3.10.0-327.36.2.el7.x86_64/modules.dep file, in addition to creating and updating several corresponding map files in the /lib/modules/3.10.0-327.36.2.el7.x86_64 directory. [root@localhost ~]# depmod -v | head -5 /lib/modules/3.10.0-327.36.2.el7.x86_64/kernel/arch/x86/crypto/ablk_helper.ko needs "cryptd_alloc_ablkcipher": /lib/modules/3.10.0-327.36.2.el7.x86_64/kernel/crypto/cryptd.ko /lib/modules/3.10.0-327.36.2.el7.x86_64/kernel/arch/x86/crypto/camellia-x86_64.ko needs "glue_cbc_encrypt_128bit": /lib/modules/3.10.0-327.36.2.el7.x86_64/kernel/arch/x86/crypto/glue_helper.ko /lib/modules/3.10.0-327.36.2.el7.x86_64/kernel/arch/x86/crypto/camellia-x86_64.ko needs "lrw_free_table": /lib/modules/3.10.0-327.36.2.el7.x86_64/kernel/crypto/lrw.ko /lib/modules/3.10.0-327.36.2.el7.x86_64/kernel/arch/x86/crypto/camellia-x86_64.ko needs "xts_crypt": /lib/modules/3.10.0-327.36.2.el7.x86_64/kernel/crypto/xts.ko /lib/modules/3.10.0-327.36.2.el7.x86_64/kernel/arch/x86/crypto/blowfish-x86_64.ko needs "blowfish_setkey": /lib/modules/3.10.0-327.36.2.el7.x86_64/kernel/crypto/blowfish_common.ko [root@localhost ~]# ls /lib/modules/3.10.0-327.36.2.el7.x86_64/ | grep modules modules.alias modules.alias.bin modules.block modules.builtin modules.builtin.bin modules.dep modules.dep.bin modules.devname modules.drm modules.modesetting modules.networking modules.order modules.softdep modules.symbols modules.symbols.bin
lshw
(дублируется в NIC, Linux hardware)
lshw -class network # полный вывод
lshw -c network -short -numeric # вывод в виде удобной таблички (short – краткий, numeric – добавляем ID устройства)
# lshw -c network -short -numeric H/W path Device Class Description ======================================================== /0/100/2/0 ens6f0 network I350 Gigabit Network Connection [8086:1521] /0/100/2/0.1 ens6f1 network I350 Gigabit Network Connection [8086:1521] /0/100/2.2/0 network 82599ES 10-Gigabit SFI/SFP+ Network Connection [8086:10FB] /0/100/2.2/0.1 network 82599ES 10-Gigabit SFI/SFP+ Network Connection [8086:10FB] /0/100/3.2/0 enp5s0f0 network BCM57840 NetXtreme II 10 Gigabit Ethernet [14E4:16A1] /0/100/3.2/0.1 enp5s0f1 network BCM57840 NetXtreme II 10 Gigabit Ethernet [14E4:16A1] /0/100/1c.4/0 enp7s0 network I210 Gigabit Network Connection [8086:1533] /0/100/1c.5/0 enp8s0 network I210 Gigabit Network Connection [8086:1533] # lshw -c network -short H/W path Device Class Description ======================================================== /0/100/2/0 ens6f0 network I350 Gigabit Network Connection /0/100/2/0.1 ens6f1 network I350 Gigabit Network Connection /0/100/2.2/0 network 82599ES 10-Gigabit SFI/SFP+ Network Connection /0/100/2.2/0.1 network 82599ES 10-Gigabit SFI/SFP+ Network Connection /0/100/3.2/0 enp5s0f0 network BCM57840 NetXtreme II 10 Gigabit Ethernet /0/100/3.2/0.1 enp5s0f1 network BCM57840 NetXtreme II 10 Gigabit Ethernet /0/100/1c.4/0 enp7s0 network I210 Gigabit Network Connection /0/100/1c.5/0 enp8s0 network I210 Gigabit Network Connection
Если девайс в списке есть, но без logical name, перезагрузить сервер или рестартовать службу командой выше. Если состояние DISABLED, то интерфейс нужно включить (ifup/ifconfig/ip link – выше примеры).
~$ sudo lshw -class network *-network description: Ethernet interface product: VMXNET3 Ethernet Controller vendor: VMware physical id: 0 bus info: pci@0000:0b:00.0 logical name: eth0 version: 01 serial: 00:50:56:b6:78:b5 capacity: 1Gbit/s width: 32 bits clock: 33MHz capabilities: pm pciexpress msi msix bus_master cap_list rom ethernet physical logical tp 1000bt-fd configuration: autonegotiation=off broadcast=yes driver=vmxnet3 driverversion=1.4.14.0-k-NAPI duplex=full ip=78.107.63.120 latency=0 link=yes multicast=yes port=twisted pair resources: irq:19 memory:fd4fb000-fd4fbfff memory:fd4fc000-fd4fcfff memory:fd4fe000-fd4fffff ioport:5000(size=16) memory:fd400000-fd40ffff *-network description: Ethernet interface product: VMXNET3 Ethernet Controller vendor: VMware physical id: 0 bus info: pci@0000:13:00.0 logical name: eth1 version: 01 serial: 00:50:56:b6:7d:ab capacity: 1Gbit/s width: 32 bits clock: 33MHz capabilities: pm pciexpress msi msix bus_master cap_list rom ethernet physical logical tp 1000bt-fd configuration: autonegotiation=off broadcast=yes driver=vmxnet3 driverversion=1.4.14.0-k-NAPI duplex=full ip=192.168.149.78 latency=0 link=yes multicast=yes port=twisted pair resources: irq:16 memory:fd3fb000-fd3fbfff memory:fd3fc000-fd3fcfff memory:fd3fe000-fd3fffff ioport:6000(size=16) memory:fd300000-fd30ffff
Если в выводе Unclaimed – вероятнее всего нужно обновлять операционную систему для обновления драйверов.
*-network:0 UNCLAIMED description: Ethernet controller
Очень удобно и наглядно и по дискам/RAM.
# lshw -c disk -short H/W path Device Class Description ====================================================== /0/100/17/0 /dev/sda disk 4011MB 4GB SATA Flash D /0/100/17/1 /dev/sdb disk 1TB TOSHIBA MG04ACA1 # lshw -c memory -short | grep iB /0/0 memory 64KiB BIOS /0/54 memory 8GiB System Memory /0/54/0 memory 4GiB DIMM DDR4 Synchronous 2133 MHz (0.5 ns) /0/54/8 memory 4GiB DIMM DDR4 Synchronous 2133 MHz (0.5 ns) /0/6c memory 384KiB L1 cache /0/6d memory 1536KiB L2 cache /0/6e memory 15MiB L3 cache /0/70 memory 384KiB L1 cache /0/71 memory 1536KiB L2 cache /0/72 memory 15MiB L3 cache
Which of the following commands will load a kernel module along with any required dependency modules?
A. depmod
B. insmod
C. modprobe
D. module_install
E. loadmod
Answer: C
What of the following statements are true regarding /dev/ when using udev? (Choose TWO correct answers.)
A. Entries for all possible devices get created on boot even if those devices are not connected.
B. Additional rules for udev can be created by adding them to /etc/udev/rules.d/.
C. When using udev, it is not possible to create block or character devices in /dev/ using mknod.
D. The /dev/ directory is a filesystem of type tmpfs and is mounted by udev during system startup.
E. The content of /dev/ is stored in /etc/udev/dev and is restored during system startup.
Answer: BD
B. Additional rules for udev can be created by adding them to /etc/udev/rules.d/. This statement is true. When using udev, additional rules can be created by adding them to /etc/udev/rules.d/. These rules can specify how udev should name devices, set permissions, and create symlinks, among other things. The rules are parsed in numeric order, so it's important to give them appropriate names to ensure that they are processed in the desired order.
D. The /dev/ directory is a filesystem of type tmpfs and is mounted by udev during system startup. This statement is true. The /dev/ directory is a special directory in the Linux filesystem that contains device files, which are used to interact with hardware devices. When using udev, the /dev/ directory is actually a filesystem of type tmpfs, which is a temporary filesystem that is stored in RAM. This means that the contents of /dev/ are not stored on disk, but are instead created dynamically by udev as devices are detected and configured.
A. Entries for all possible devices get created on boot even if those devices are not connected. This statement is false. When using udev, only entries for devices that are actually connected to the system are created in the /dev/ directory. This is in contrast to earlier versions of Linux, where entries for all possible devices were created at boot time, regardless of whether they were actually connected or not.
C. When using udev, it is not possible to create block or character devices in /dev/ using mknod. This statement is true. When using udev, device nodes are created dynamically as devices are detected and configured, so it is not necessary (or recommended) to manually create device nodes using mknod. In fact, attempting to create device nodes using mknod can interfere with udev's automatic device configuration and cause problems. Instead, additional rules for udev should be added to /etc/udev/rules.d/ to specify how devices should be named and configured.
E. The content of /dev/ is stored in /etc/udev/dev and is restored during system startup. This statement is false. There is no file or directory named /etc/udev/dev that stores the content of /dev/. As mentioned earlier, the contents of /dev/ are created dynamically by udev as devices are detected and configured, and are stored in a tmpfs filesystem.
mknod mkfifo
Команда mknod позволяет задействовать одноименную утилиту, предназначенную для создания файлов устройств и именованных каналов. Вообще, данная команда практически не используется в наше время ввиду того, что файлы устройств создаются автоматически средствами подсистемы Udev, а файлы именованных каналов — средствами команды mkfifo, которая проще в использовании. Тем не менее, он не утратила своих свойств и может использоваться даже сейчас при определенных обстоятельствах.