#
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# linuxrc.Commands.Help.txt
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#
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# 02-Nov-04 amo Create a minimal initrd.gz to load the rootfs.gz as /
# 13-Nov-04 amo Split off ramdisk options into linuxrc.Commands.Help.txt
#
#
# =============
# #
# # NOTE
# #
# =============
#	- you cannot manually invoke /sbin/init from a command line
#
#	- if you do, you will get the following error message:
#		"error opening/writing control channel /dev/initctl"
#
#
#
# For Normal ramdisk/rootfs setup
# --------------------------------
#	lilo: linux-2.4.27	- will call /sbin/init when linuxrc is done
#
#
#	"man initrd" says to unmount everything before existing linuxrc
#	but we're still using/needing /mnt/hda/rootfs
#
#
#	Upon exiting /linuxrc, normal /sbin/init will be invoked
#	and /dev/ram0 will have been previously moved to /initrd
#
#
# For Manual ramdisk/rootfs setup
# -------------------------------
#
#	#
#	# this root=/dev/ram0 will execute linuxrc ( sorta useless to just specify root= )
#	#
#	lilo: linux-2.4.27 root=/dev/ram0 
#
#
#	#
#	# these root= and init=  will NOT execute linuxrc
#	# modify linuxrc to call linuxrc.loop or /bin/bash as desired first
#	#
#	lilo: linux-2.4.27 root=/dev/ram0 init=/bin/bash
#		( check and run linuxrc.bash.txt if you don't want to type )
#		#
#		# mount /proc
#		#
#		mount -t proc none /proc
#
#		#
#		# make it rw if we want to edit /linuxrc or anything else
#		#
#		mount -n -o rw,remount /dev/ram0 /
#
#		#
#		# run /linuxrc as if it was executed normally
#		#
#		sh /linuxrc
#
#		#
#		# change into the rootFS 
#		#
#		chroot /mnt/loop /bin/bash
#
#
# We're in the rootFS
# --------------------
#	#
#	# run the /linuxrc.loop commands in lieu of /sbin/init
#	#
#	sh /linuxrc.loop
#	
#	# colorize the screen
#	sh /root/.alias
#
#	#
#	# create some ramdisks
#	#
#	sh /root/ramdisks.sh
#
#	#
#	# invoke normal single user
#	#
#	cd /etc/rc.d ; ./rc.S
#
#	#
#	# invoke normal multi-user 
#	#
#	cd /etc/rc.d ; ./rc.M
#
#	# ping the work as normal
#	route -nv
#	ping yahooc.om
#
#	#
#	# install a firewall
#	#
#	cd /etc/rc.d ; ./rc.iptables
#
#
# Other Commands useful in ramdisks
# ---------------------------------
#	#
#	# to Mount a Loop Device
#	#
#	mount -o loop filename /dev/loop0
#
#	#
# 	# to change / for testing linuxrc.loop or rootfs
#	#
#	chroot /mnt/loop0 /
#
#
#
# -------------------------------------
# "chroot /mnt/loop0 exec /sbin/init 1"
# "chroot /mnt/loop0 /sbin/init 3"
# -------------------------------------
#
#	init also expects a run level
#
#	a shell ( including /linuxrc ) CANNOT call init --> causes error message:
#
#	=======================================================
#	#
#	# "error opening/writing control channel /dev/initctl"
#	#
#	=======================================================
#
#
# pivot_root
# -------------
#	=======================================================
#	#
#	# "device or resource busy"
#	#
#	=======================================================
#
#
# To View the RootFS
# -------------------
#	mount /dev/hda1 /mnt/hda
#	losetup /dev/loop0 /mnt/hda/boot/rootfs
#	mount -o loop,rw /dev/loop0 /mnt/loop0
#
#
# Which Shells
# ------------
#	http://www.busybox.net
#	http://www.ibiblio.org/pub/Linux/system/shells/
#
#
#
# Release the memory after we're done
# ------------------------------------
#	freeram
#	blockdev --flushbufs /dev/ram0
#
# ================================================================
#
# Which is the roofs it will boot
# -------------------------------
#	rdev /boot/vmlinuz-2.4.27
#
# Set the rootfs on the kernel to user /dev/loop0
# ------------------------------------------------
#	rdev /boot/vmlinuz-2.4.27  /dev/loop0
#
# more whacky options
# --------------------
#	rdev -R /dev/fd0 0
#	  ?? - or - ??
#	rdev -r /dev/fd0 0
#
#	rdev /dev/fd0 /dev/fd0
#	rdev -R /dev/fd0 49552
#	rdev -r /dev/fd0 49552
#
# ================================================================
#
# Loop Devices
# --------------
#
#	0100	/dev/ram0	
#	0700	/dev/loop0
#	0301	/dev/ram1
#
# echo "0x700" > /proc/sys/kernel/real_root_dev
#
#
# http://webpages.charter.net/decibelshelp/LinuxHelp4_PartImage.html
#	rdev vmlinuz /dev/fd0
#	rdev -r vmlinuz 49152
#	rdev -R vmlinuz 0
#
# http://www.linuxfromscratch.org/blfs/view/cvs/postlfs/config.html
#	#
#	# Join rescueimage and initrd onto a diskette
#	# 
#	dd if=rescueimage of=/dev/floppy/0 bs=1k
#	rdev /dev/floppy/0 0,0
#	rdev -R /dev/floppy/0 0
#
#	rdev -r /dev/floppy/0 16865
#		16865 = 481 + 16,384 ( ie 2**14) 
#
#	dd if=/tmp/rootfs.gz of=/dev/fd0 bs=1k seek=481
#		481 is dd's output +1
#
# ================================================================
#
#
# From man initrd
# ---------------
#	"man initrd" says to unmount everything before existing linuxrc
#	but we're still using/needing /mnt/hda/rootfs
# 
# 
#	# unmount the compact flash
#	umount /mnt/CF
#
#
#	# leave /proc, since echo fails 
#	umount /proc
#
#
#	Upon exiting /linuxrc, normal /sbin/init will be invoked
#	and /dev/ram0 will have been previously moved to /initrd
#
#
#	except in our /dev/loop case, / cannot be mounted since
#	/dev/loop0 does not yet exist in the real rootFS, so we
#	will use linuxrc.loop instead
#
#
# ================================================================
#
# What causes:
# ------------
#	pivot_root:  device or resource busy
#
# ----------------------
#
#	pivot_root /mnt/loop0 /initrd
#	chroot /mnt/loop0 /sbin/init 3
#
#	cd /mnt/loop0 && pivot_root . /initrd
#
#
# dumps you into /mnt/loop0 and does not execute /sbin/init
# docmd "exec chroot . "
#
#
#
# -
# - pivot_root is needed for chroot + init to work
# -
#
# http://www.sdc.org/~leila/usb-dongle/usb-filesystem/linuxrc
#
#	cd /mnt/loop0 
#	/sbin/pivot_root . /initrd 
#	exec /usr/bin/chroot . /sbin/init 3 
#	exec chroot . /sbin/init < dev/console 2>&1 
#
#
#
# To manually see what's going on rootFS
# --------------------------------------
#
# chroot /mnt/loop0 /bin/bash
# chroot /mnt/loop0 /linuxrc.loop
#
#
#	a shell ( including /linuxrc ) CANNOT call init --> causes error message:
#	"error opening/writing control channel /dev/initctl"
#
#	# chroot /mnt/loop0 /sbin/init 1
#
#
#
#
# End of file