Linux中inittab文件语法及作用

# /etc/inittab init(8) configuration for BusyBox## Copyright (C) 1999-2004 by Erik Andersen <[e-mail]>### Note, BusyBox init doesn't 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 isn't you may have strange results.  If this#field is left blank, then the init's stdin/out will be used.## <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: unrecognized 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 it's 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#         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 -a