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问,linux中/dev下的文件
来源: 互联网 发布时间:2016-08-10
本文导语: 我想知道/dev这个文件目录是在什么时候生成的,依据什么产生的目录,所有的文件都有用吗,都有实际的设备对应吗? | 读一下udev的实现机制就知道了. 在sysfs以前也就是2.4的kernel的时候, /d...
我想知道/dev这个文件目录是在什么时候生成的,依据什么产生的目录,所有的文件都有用吗,都有实际的设备对应吗?
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读一下udev的实现机制就知道了.
在sysfs以前也就是2.4的kernel的时候, /dev下面是驱动在注册的时候产生的, 到了2.6的kernel, 引入了
sysfs文件系统, /dev下面的设备是udev按照udev的规则产生的, udev在启动的时候会去遍历/sys下面的一些硬件设备, 然后按照/etc/udev/rules下面的命名规则来创建设备.
[root@Mother--FC4 SPECS]# cat /etc/udev/rules.d/50-udev.rules
# There are a number of modifiers that are allowed to be used in some of the
# fields. See the udev man page for a full description of them.
#
# default is OWNER="root" GROUP="root", MODE="0600"
#
# all block devices
SUBSYSTEM=="block", GROUP="disk", MODE="0640"
# console devices
KERNEL=="tty", MODE="0666"
KERNEL=="tty[0-9]", GROUP="tty", MODE="0660"
KERNEL=="tty[0-9][0-9]*", GROUP="tty", MODE="0660"
KERNEL=="vc/[0-9]*", GROUP="tty", MODE="0660"
# pty devices
# Set this to 0660 if you only want users belonging to tty group
# to be able to allocate PTYs
KERNEL=="ptmx", GROUP="tty", MODE="0666"
KERNEL=="pty[p-za-e][0-9a-f]*", GROUP="tty", MODE="0660"
KERNEL=="tty[p-za-e][0-9a-f]*", GROUP="tty", MODE="0660"
KERNEL=="pty/m*", GROUP="tty", MODE="0660"
KERNEL=="vc/s*", GROUP="tty", MODE="0660"
#####add by wallace
# serial+dialup devices
KERNEL=="ttyS*", GROUP="uucp", MODE="0660"
KERNEL=="ippp*", MODE="0660"
KERNEL=="isdn*", MODE="0660"
KERNEL=="isdnctrl*", MODE="0660"
KERNEL=="capi*", MODE="0660"
KERNEL=="dcbri*", MODE="0660"
KERNEL=="ircomm*", GROUP="uucp", MODE="0660"
KERNEL=="ttyUSB*", GROUP="uucp", MODE="0660"
KERNEL=="tts/[0-9]*", GROUP="uucp", MODE="0660"
KERNEL=="tts/USB[0-9]*", GROUP="uucp", MODE="0660"
# vc devices
KERNEL=="vcs", OWNER="vcsa", GROUP="tty"
KERNEL=="vcs[0-9]*", OWNER="vcsa", GROUP="tty"
KERNEL=="vcsa", OWNER="vcsa", GROUP="tty"
KERNEL=="vcsa[0-9]*", OWNER="vcsa", GROUP="tty"
KERNEL=="vcc/*", OWNER="vcsa", GROUP="tty"
# memory devices
KERNEL=="random", MODE="0666"
KERNEL=="urandom", MODE="0444"
KERNEL=="mem", GROUP="kmem", MODE="0640"
KERNEL=="kmem", GROUP="kmem", MODE="0640"
KERNEL=="port", GROUP="kmem", MODE="0640"
KERNEL=="full", MODE="0666"
KERNEL=="null", MODE="0666"
KERNEL=="zero", MODE="0666"
# misc devices
KERNEL=="nvram", MODE="0660"
KERNEL=="rtc", MODE="0644"
# floppy devices
KERNEL=="fd[01]*", GROUP="floppy", MODE="0660"
# audio devices
KERNEL=="dsp*", MODE="0660"
KERNEL=="audio*", MODE="0660"
KERNEL=="midi*", MODE="0660"
KERNEL=="mixer*", MODE="0660"
KERNEL=="sequencer*", MODE="0660"
KERNEL=="sound/*", MODE="0660"
KERNEL=="snd/*", MODE="0660"
KERNEL=="beep", MODE="0660"
KERNEL=="admm*", MODE="0660"
KERNEL=="adsp*", MODE="0660"
KERNEL=="aload*", MODE="0660"
KERNEL=="amidi*", MODE="0660"
KERNEL=="dmfm*", MODE="0660"
KERNEL=="dmmidi*", MODE="0660"
KERNEL=="sndstat", MODE="0660"
# pilot/palm devices
KERNEL=="pilot", GROUP="uucp", MODE="0660"
# lp devices
KERNEL=="lp*", GROUP="lp", MODE="0660"
KERNEL=="parport*", GROUP="lp", MODE="0660"
KERNEL=="irlpt*", GROUP="lp", MODE="0660"
KERNEL=="usblp*", GROUP="lp", MODE="0660"
KERNEL=="usb/lp*", GROUP="lp", MODE="0660"
# tape devices
KERNEL=="ht*", GROUP="disk", MODE="0640"
KERNEL=="nht*", GROUP="disk", MODE="0640"
KERNEL=="pt[0-9]*", GROUP="disk", MODE="0640"
KERNEL=="npt*", GROUP="disk", MODE="0640"
KERNEL=="st*", GROUP="disk", MODE="0640"
KERNEL=="nst*", GROUP="disk", MODE="0640"
KERNEL=="osst*", GROUP="disk", MODE="0640"
KERNEL=="nosst*", GROUP="disk", MODE="0640"
# diskonkey devices
KERNEL=="diskonkey*", GROUP="disk", MODE="0640"
# rem_ide devices
KERNEL=="microdrive*", GROUP="disk", MODE="0640"
# kbd devices
KERNEL=="kbd", MODE="0644"
# joystick devices
KERNEL=="js[0-9]*", MODE="0644"
KERNEL=="djs[0-9]*", MODE="0644"
# v4l devices
KERNEL=="video*", MODE="0660"
KERNEL=="radio*", MODE="0660"
KERNEL=="winradio*", MODE="0660"
KERNEL=="vtx*", MODE="0660"
KERNEL=="vbi*", MODE="0660"
KERNEL=="video/*", MODE="0660"
KERNEL=="vttuner", MODE="0660"
KERNEL=="v4l/*", MODE="0660"
# input devices
KERNEL=="input/*", MODE="0660"
# gpm devices
KERNEL=="gpmctl", MODE="0700"
# dri devices
KERNEL=="nvidia*", MODE="0660"
KERNEL=="3dfx*", MODE="0660"
KERNEL=="dri/*", MODE="0666"
# usb devices
KERNEL=="usb/dabusb*", GROUP="usb", MODE="0660"
KERNEL=="usb/mdc800*", GROUP="usb", MODE="0660"
KERNEL=="usb/rio500", GROUP="usb", MODE="0660"
# s390 devices
KERNEL=="z90crypt", MODE="0666"
# DVB
KERNEL=="dvb/*", MODE="0660"
KERNEL=="dvb", MODE="0660"
KERNEL=="dvb/adapter*", MODE="0660"
# create a symlink named after the device map name
# note devmap_name comes with extras/multipath
#KERNEL=="dm-[0-9]*", PROGRAM="/sbin/devmap_name %M %m", NAME="%k", SYMLINK="%c"
# DRI devices always go into a subdirectory (as per the LSB spec)
KERNEL=="card*", NAME="dri/card%n"
# alsa devices
KERNEL=="controlC[0-9]*", NAME="snd/%k"
KERNEL=="hw[CD0-9]*", NAME="snd/%k"
KERNEL=="pcm[CD0-9cp]*", NAME="snd/%k"
KERNEL=="midi[CD0-9]*", NAME="snd/%k"
KERNEL=="timer", NAME="snd/%k"
KERNEL=="seq", NAME="snd/%k"
# input devices
KERNEL=="mice", NAME="input/%k"
KERNEL=="mouse*", NAME="input/%k"
KERNEL=="event*", NAME="input/%k"
KERNEL=="js*", NAME="input/%k"
KERNEL=="ts*", NAME="input/%k"
KERNEL=="raw[0-9]*", NAME="raw/%k"
KERNEL=="lp[0-9]*", SYMLINK="par%n"
BUS=="usb", KERNEL=="lp[0-9]*", NAME="usb/%k"
KERNEL=="microcode", NAME="cpu/%k"
KERNEL=="ram1", SYMLINK="ram"
KERNEL=="video0", SYMLINK="video"
KERNEL=="radio0", SYMLINK="radio"
KERNEL=="audio0", SYMLINK="audio"
KERNEL=="dsp0", SYMLINK="dsp"
KERNEL=="fb0", SYMLINK="fb"
KERNEL=="qft0", SYMLINK="ftape"
KERNEL=="isdnctrl0", SYMLINK="isdnctrl"
KERNEL=="mixer0", SYMLINK="mixer"
KERNEL=="ram0", SYMLINK="ramdisk"
KERNEL=="sbpcd0", SYMLINK="sbpcd"
KERNEL=="radio0", SYMLINK="radio"
KERNEL=="tty0", SYMLINK="systty"
KERNEL=="vbi0", SYMLINK="vbi"
KERNEL=="null", SYMLINK="XOR"
KERNEL=="tun", NAME="net/%k"
KERNEL=="device-mapper", NAME="mapper/control"
# old compat symlinks with enumeration
KERNEL=="sr[0-9]*", SYMLINK="cdrom%e"
KERNEL=="scd[0-9]*", SYMLINK="cdrom%e"
KERNEL=="pcd[0-9]*", SYMLINK="cdrom%e"
KERNEL=="fd[0-9]*", SYMLINK="floppy%e"
KERNEL=="nst[0-9]", BUS=="scsi", SYMLINK="tape%e"
KERNEL=="nosst[0-9]", BUS=="scsi", SYMLINK="tape%e"
KERNEL=="umad*", NAME="infiniband/%k"
KERNEL=="issm*", NAME="infiniband/%k"
# Section for zaptel device
KERNEL=="zapctl", NAME="zap/ctl"
KERNEL=="zaptimer", NAME="zap/timer"
KERNEL=="zapchannel", NAME="zap/channel"
KERNEL=="zappseudo", NAME="zap/pseudo"
KERNEL=="zap[0-9]*", NAME="zap/%n"
# do not seperate the next 2 lines!!
KERNEL=="hd[a-z]", BUS=="ide", SYSFS{removable}=="1", PROGRAM=="/etc/udev/scripts/ide-media.sh %k", RESULT=="floppy", SYMLINK="floppy%e", NAME{ignore_remove, all_partitions}="%k"
KERNEL=="hd[a-z]", BUS=="ide", SYSFS{removable}=="1", RESULT=="cdrom", SYMLINK="cdrom%e"
KERNEL=="hd[a-z]", BUS=="ide", SYSFS{removable}=="1", PROGRAM=="/etc/udev/scripts/check-cdrom.sh %k DVD", SYMLINK="dvd%e"
KERNEL=="sr[0-9]*", BUS=="scsi", PROGRAM=="/etc/udev/scripts/check-cdrom.sh %k DVD", SYMLINK="dvd%e"
KERNEL=="hd[a-z]", BUS=="ide", SYSFS{removable}=="1", PROGRAM=="/etc/udev/scripts/check-cdrom.sh %k CD-R", SYMLINK="cdwriter%e"
KERNEL=="sr[0-9]*", BUS=="scsi", PROGRAM=="/etc/udev/scripts/check-cdrom.sh %k CD-R", SYMLINK="cdwriter%e"
KERNEL=="hd[a-z]", BUS=="ide", SYSFS{removable}=="1", PROGRAM="/etc/udev/scripts/check-cdrom.sh %k DVD-R", SYMLINK="dvdwriter%e"
KERNEL=="sr[0-9]*", BUS=="scsi", PROGRAM=="/etc/udev/scripts/check-cdrom.sh %k DVD-R", SYMLINK="dvdwriter%e"
# rename sr* to scd*
KERNEL=="sr[0-9]*", BUS=="scsi", NAME="scd%n"
KERNEL=="hd[a-z]*", BUS=="ide", SYSFS{removable}=="1", NAME{ignore_remove}="%k"
KERNEL=="dvb*", PROGRAM=="/etc/udev/scripts/dvb.sh %k", NAME="%c"
[root@Mother--FC4 SPECS]#
在sysfs以前也就是2.4的kernel的时候, /dev下面是驱动在注册的时候产生的, 到了2.6的kernel, 引入了
sysfs文件系统, /dev下面的设备是udev按照udev的规则产生的, udev在启动的时候会去遍历/sys下面的一些硬件设备, 然后按照/etc/udev/rules下面的命名规则来创建设备.
[root@Mother--FC4 SPECS]# cat /etc/udev/rules.d/50-udev.rules
# There are a number of modifiers that are allowed to be used in some of the
# fields. See the udev man page for a full description of them.
#
# default is OWNER="root" GROUP="root", MODE="0600"
#
# all block devices
SUBSYSTEM=="block", GROUP="disk", MODE="0640"
# console devices
KERNEL=="tty", MODE="0666"
KERNEL=="tty[0-9]", GROUP="tty", MODE="0660"
KERNEL=="tty[0-9][0-9]*", GROUP="tty", MODE="0660"
KERNEL=="vc/[0-9]*", GROUP="tty", MODE="0660"
# pty devices
# Set this to 0660 if you only want users belonging to tty group
# to be able to allocate PTYs
KERNEL=="ptmx", GROUP="tty", MODE="0666"
KERNEL=="pty[p-za-e][0-9a-f]*", GROUP="tty", MODE="0660"
KERNEL=="tty[p-za-e][0-9a-f]*", GROUP="tty", MODE="0660"
KERNEL=="pty/m*", GROUP="tty", MODE="0660"
KERNEL=="vc/s*", GROUP="tty", MODE="0660"
#####add by wallace
# serial+dialup devices
KERNEL=="ttyS*", GROUP="uucp", MODE="0660"
KERNEL=="ippp*", MODE="0660"
KERNEL=="isdn*", MODE="0660"
KERNEL=="isdnctrl*", MODE="0660"
KERNEL=="capi*", MODE="0660"
KERNEL=="dcbri*", MODE="0660"
KERNEL=="ircomm*", GROUP="uucp", MODE="0660"
KERNEL=="ttyUSB*", GROUP="uucp", MODE="0660"
KERNEL=="tts/[0-9]*", GROUP="uucp", MODE="0660"
KERNEL=="tts/USB[0-9]*", GROUP="uucp", MODE="0660"
# vc devices
KERNEL=="vcs", OWNER="vcsa", GROUP="tty"
KERNEL=="vcs[0-9]*", OWNER="vcsa", GROUP="tty"
KERNEL=="vcsa", OWNER="vcsa", GROUP="tty"
KERNEL=="vcsa[0-9]*", OWNER="vcsa", GROUP="tty"
KERNEL=="vcc/*", OWNER="vcsa", GROUP="tty"
# memory devices
KERNEL=="random", MODE="0666"
KERNEL=="urandom", MODE="0444"
KERNEL=="mem", GROUP="kmem", MODE="0640"
KERNEL=="kmem", GROUP="kmem", MODE="0640"
KERNEL=="port", GROUP="kmem", MODE="0640"
KERNEL=="full", MODE="0666"
KERNEL=="null", MODE="0666"
KERNEL=="zero", MODE="0666"
# misc devices
KERNEL=="nvram", MODE="0660"
KERNEL=="rtc", MODE="0644"
# floppy devices
KERNEL=="fd[01]*", GROUP="floppy", MODE="0660"
# audio devices
KERNEL=="dsp*", MODE="0660"
KERNEL=="audio*", MODE="0660"
KERNEL=="midi*", MODE="0660"
KERNEL=="mixer*", MODE="0660"
KERNEL=="sequencer*", MODE="0660"
KERNEL=="sound/*", MODE="0660"
KERNEL=="snd/*", MODE="0660"
KERNEL=="beep", MODE="0660"
KERNEL=="admm*", MODE="0660"
KERNEL=="adsp*", MODE="0660"
KERNEL=="aload*", MODE="0660"
KERNEL=="amidi*", MODE="0660"
KERNEL=="dmfm*", MODE="0660"
KERNEL=="dmmidi*", MODE="0660"
KERNEL=="sndstat", MODE="0660"
# pilot/palm devices
KERNEL=="pilot", GROUP="uucp", MODE="0660"
# lp devices
KERNEL=="lp*", GROUP="lp", MODE="0660"
KERNEL=="parport*", GROUP="lp", MODE="0660"
KERNEL=="irlpt*", GROUP="lp", MODE="0660"
KERNEL=="usblp*", GROUP="lp", MODE="0660"
KERNEL=="usb/lp*", GROUP="lp", MODE="0660"
# tape devices
KERNEL=="ht*", GROUP="disk", MODE="0640"
KERNEL=="nht*", GROUP="disk", MODE="0640"
KERNEL=="pt[0-9]*", GROUP="disk", MODE="0640"
KERNEL=="npt*", GROUP="disk", MODE="0640"
KERNEL=="st*", GROUP="disk", MODE="0640"
KERNEL=="nst*", GROUP="disk", MODE="0640"
KERNEL=="osst*", GROUP="disk", MODE="0640"
KERNEL=="nosst*", GROUP="disk", MODE="0640"
# diskonkey devices
KERNEL=="diskonkey*", GROUP="disk", MODE="0640"
# rem_ide devices
KERNEL=="microdrive*", GROUP="disk", MODE="0640"
# kbd devices
KERNEL=="kbd", MODE="0644"
# joystick devices
KERNEL=="js[0-9]*", MODE="0644"
KERNEL=="djs[0-9]*", MODE="0644"
# v4l devices
KERNEL=="video*", MODE="0660"
KERNEL=="radio*", MODE="0660"
KERNEL=="winradio*", MODE="0660"
KERNEL=="vtx*", MODE="0660"
KERNEL=="vbi*", MODE="0660"
KERNEL=="video/*", MODE="0660"
KERNEL=="vttuner", MODE="0660"
KERNEL=="v4l/*", MODE="0660"
# input devices
KERNEL=="input/*", MODE="0660"
# gpm devices
KERNEL=="gpmctl", MODE="0700"
# dri devices
KERNEL=="nvidia*", MODE="0660"
KERNEL=="3dfx*", MODE="0660"
KERNEL=="dri/*", MODE="0666"
# usb devices
KERNEL=="usb/dabusb*", GROUP="usb", MODE="0660"
KERNEL=="usb/mdc800*", GROUP="usb", MODE="0660"
KERNEL=="usb/rio500", GROUP="usb", MODE="0660"
# s390 devices
KERNEL=="z90crypt", MODE="0666"
# DVB
KERNEL=="dvb/*", MODE="0660"
KERNEL=="dvb", MODE="0660"
KERNEL=="dvb/adapter*", MODE="0660"
# create a symlink named after the device map name
# note devmap_name comes with extras/multipath
#KERNEL=="dm-[0-9]*", PROGRAM="/sbin/devmap_name %M %m", NAME="%k", SYMLINK="%c"
# DRI devices always go into a subdirectory (as per the LSB spec)
KERNEL=="card*", NAME="dri/card%n"
# alsa devices
KERNEL=="controlC[0-9]*", NAME="snd/%k"
KERNEL=="hw[CD0-9]*", NAME="snd/%k"
KERNEL=="pcm[CD0-9cp]*", NAME="snd/%k"
KERNEL=="midi[CD0-9]*", NAME="snd/%k"
KERNEL=="timer", NAME="snd/%k"
KERNEL=="seq", NAME="snd/%k"
# input devices
KERNEL=="mice", NAME="input/%k"
KERNEL=="mouse*", NAME="input/%k"
KERNEL=="event*", NAME="input/%k"
KERNEL=="js*", NAME="input/%k"
KERNEL=="ts*", NAME="input/%k"
KERNEL=="raw[0-9]*", NAME="raw/%k"
KERNEL=="lp[0-9]*", SYMLINK="par%n"
BUS=="usb", KERNEL=="lp[0-9]*", NAME="usb/%k"
KERNEL=="microcode", NAME="cpu/%k"
KERNEL=="ram1", SYMLINK="ram"
KERNEL=="video0", SYMLINK="video"
KERNEL=="radio0", SYMLINK="radio"
KERNEL=="audio0", SYMLINK="audio"
KERNEL=="dsp0", SYMLINK="dsp"
KERNEL=="fb0", SYMLINK="fb"
KERNEL=="qft0", SYMLINK="ftape"
KERNEL=="isdnctrl0", SYMLINK="isdnctrl"
KERNEL=="mixer0", SYMLINK="mixer"
KERNEL=="ram0", SYMLINK="ramdisk"
KERNEL=="sbpcd0", SYMLINK="sbpcd"
KERNEL=="radio0", SYMLINK="radio"
KERNEL=="tty0", SYMLINK="systty"
KERNEL=="vbi0", SYMLINK="vbi"
KERNEL=="null", SYMLINK="XOR"
KERNEL=="tun", NAME="net/%k"
KERNEL=="device-mapper", NAME="mapper/control"
# old compat symlinks with enumeration
KERNEL=="sr[0-9]*", SYMLINK="cdrom%e"
KERNEL=="scd[0-9]*", SYMLINK="cdrom%e"
KERNEL=="pcd[0-9]*", SYMLINK="cdrom%e"
KERNEL=="fd[0-9]*", SYMLINK="floppy%e"
KERNEL=="nst[0-9]", BUS=="scsi", SYMLINK="tape%e"
KERNEL=="nosst[0-9]", BUS=="scsi", SYMLINK="tape%e"
KERNEL=="umad*", NAME="infiniband/%k"
KERNEL=="issm*", NAME="infiniband/%k"
# Section for zaptel device
KERNEL=="zapctl", NAME="zap/ctl"
KERNEL=="zaptimer", NAME="zap/timer"
KERNEL=="zapchannel", NAME="zap/channel"
KERNEL=="zappseudo", NAME="zap/pseudo"
KERNEL=="zap[0-9]*", NAME="zap/%n"
# do not seperate the next 2 lines!!
KERNEL=="hd[a-z]", BUS=="ide", SYSFS{removable}=="1", PROGRAM=="/etc/udev/scripts/ide-media.sh %k", RESULT=="floppy", SYMLINK="floppy%e", NAME{ignore_remove, all_partitions}="%k"
KERNEL=="hd[a-z]", BUS=="ide", SYSFS{removable}=="1", RESULT=="cdrom", SYMLINK="cdrom%e"
KERNEL=="hd[a-z]", BUS=="ide", SYSFS{removable}=="1", PROGRAM=="/etc/udev/scripts/check-cdrom.sh %k DVD", SYMLINK="dvd%e"
KERNEL=="sr[0-9]*", BUS=="scsi", PROGRAM=="/etc/udev/scripts/check-cdrom.sh %k DVD", SYMLINK="dvd%e"
KERNEL=="hd[a-z]", BUS=="ide", SYSFS{removable}=="1", PROGRAM=="/etc/udev/scripts/check-cdrom.sh %k CD-R", SYMLINK="cdwriter%e"
KERNEL=="sr[0-9]*", BUS=="scsi", PROGRAM=="/etc/udev/scripts/check-cdrom.sh %k CD-R", SYMLINK="cdwriter%e"
KERNEL=="hd[a-z]", BUS=="ide", SYSFS{removable}=="1", PROGRAM="/etc/udev/scripts/check-cdrom.sh %k DVD-R", SYMLINK="dvdwriter%e"
KERNEL=="sr[0-9]*", BUS=="scsi", PROGRAM=="/etc/udev/scripts/check-cdrom.sh %k DVD-R", SYMLINK="dvdwriter%e"
# rename sr* to scd*
KERNEL=="sr[0-9]*", BUS=="scsi", NAME="scd%n"
KERNEL=="hd[a-z]*", BUS=="ide", SYSFS{removable}=="1", NAME{ignore_remove}="%k"
KERNEL=="dvb*", PROGRAM=="/etc/udev/scripts/dvb.sh %k", NAME="%c"
[root@Mother--FC4 SPECS]#
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dev目录详解http://blog.chinaunix.net/u3/94284/showart_1982242.html
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device
设备文件
/dev/MAKEDEV描述
设备文件
/dev/MAKEDEV描述