淮安市做网站,写作网站哪个名声好,小程序网站做多大尺寸,很多网站的微信登录怎么做讲init进程的启动过程从/etc/inittab出发。 内核启动init进程时已经打开/dev/console设备作为控制台#xff0c;一般情况下Busybox init程序就使用/dev/console#xff0c; 如果内核启动init进程的同时设置了环境变量CONSOLE或console#xff0c;则使用环境变量所指定的设备… 讲init进程的启动过程从/etc/inittab出发。 内核启动init进程时已经打开/dev/console设备作为控制台一般情况下Busybox init程序就使用/dev/console 如果内核启动init进程的同时设置了环境变量CONSOLE或console则使用环境变量所指定的设备。 1、/etc/inittab文件的相关文档和示例代码都在Busybox 的examples/inittab文件中。 vi examples/inittab 内容如下(红色字为格式重要部分) # /etc/inittab init(8) configuration for BusyBox## Copyright (C) 1999-2004 by Erik Andersen andersencodepoet.org### Note, BusyBox init doesnt support runlevels. The runlevels field is# completely ignored by BusyBox init. If you want runlevels, use sysvinit.### Format for each entry: id:runlevels:action:process## id: WARNING: This field has a non-traditional meaning for BusyBox init!## The id field is used by BusyBox init to specify the controlling tty for# the specified process to run on. The contents of this field are# appended to /dev/ and used as-is. There is no need for this field to# be unique, although if it isnt you may have strange results. If this# field is left blank, it is completely ignored. Also note that if# BusyBox detects that a serial console is in use, then all entries# containing non-empty id fields will be ignored. BusyBox init does# nothing with utmp. We dont need no stinkin utmp.runlevels: The runlevels field is completely ignored.## action: Valid actions include: sysinit, respawn, askfirst, wait, once,# restart, ctrlaltdel, and shutdown.## Note: askfirst acts just like respawn, but before running the specified# process it displays the line Please press Enter to activate this# console. and then waits for the user to press enter before starting# the specified process.## Note: unrecognised actions (like initdefault) will cause init to emit# an error message, and then go along with its business.## process: Specifies the process to be executed and its command line.## Note: BusyBox init works just fine without an inittab. If no inittab is# found, it has the following default behavior:# ::sysinit:/etc/init.d/rcS# ::askfirst:/bin/sh# ::ctrlaltdel:/sbin/reboot# ::shutdown:/sbin/swapoff -a# ::shutdown:/bin/umount -a -r# ::restart:/sbin/init## if it detects that /dev/console is _not_ a serial console, it will# also run:# tty2::askfirst:/bin/sh# tty3::askfirst:/bin/sh# tty4::askfirst:/bin/sh## Boot-time system configuration/initialization script.# This is run first except when booting in single-user mode.#::sysinit:/etc/init.d/rcS# /bin/sh invocations on selected ttys## Note below that we prefix the shell commands with a - to indicate to the# shell that it is supposed to be a login shell. Normally this is handled by# login, but since we are bypassing login in this case, BusyBox lets you do# this yourself...## Start an askfirst shell on the console (whatever that may be)::askfirst:-/bin/sh# Start an askfirst shell on /dev/tty2-4tty2::askfirst:-/bin/shtty3::askfirst:-/bin/shtty4::askfirst:-/bin/sh# /sbin/getty invocations for selected ttystty4::respawn:/sbin/getty 38400 tty5tty5::respawn:/sbin/getty 38400 tty6# Example of how to put a getty on a serial line (for a terminal)#::respawn:/sbin/getty -L ttyS0 9600 vt100#::respawn:/sbin/getty -L ttyS1 9600 vt100## Example how to put a getty on a modem line.#::respawn:/sbin/getty 57600 ttyS2# Stuff to do when restarting the init process::restart:/sbin/init# Stuff to do before rebooting::ctrlaltdel:/sbin/reboot::shutdown:/bin/umount -a -r::shutdown:/sbin/swapoff -a2、仿照Busybox 的examples/inittab 文件创建一个inittab文件内容如下 #/etc/inittab #init进程启动的第一个子进程它是一个脚本可以在里面指定用户想执行的操作 #比较挂接其他文件系统、配置网络等 ::sysinit:/etc/init.d/rcS #启动shell以/dev/ttySAC0作为控制台 ttySAC0::askfirst:-/bin/sh #按下CtrlAltDel之后执行的程序不过在串口控制台中无法输入CtrlAltDel组合键 ::ctrlaltdel:/sbin/reboot #重启、关机前执行的程序 ::shutdown:/bin/umount -a -r
