Linux From Scratch
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# Creating the rc script

The first main bootscript is the `/etc/init.d/rc` script. Create a new file `/etc/init.d/rc` containing the following:

`cat > rc << "EOF"`
#!/bin/sh
# Begin /etc/init.d/rc
#
# By Jason Pearce - jason.pearce@linux.org
# Modified by Gerard Beekmans - gerard@linuxfromscratch.org
# print_error_msg based on ideas by Simon Perreault - nomis80@yahoo.com
#
# Include the functions declared in the /etc/init.d/functions file
#
source /etc/init.d/functions
#
# The print_error_msg function prints an error message when an unforseen
# error occured that wasn't trapped for some reason by a evaluate_retval
# call or error checking in different ways.
print_error_msg()
{
echo
$FAILURE
echo -n "You should not read this error message. It means "
echo "that an unforseen error "
echo -n "took place and subscript $i exited with "
echo "a return value "
echo -n "of $error_value for an unknown reason. If you're able "
echo "to trace this error down "
echo -n "to a bug in one of the files provided by this book, "
echo "please be so kind to "
echo -n "inform us at lfs-discuss@linuxfromscratch.org"
$NORMAL
echo
echo
echo "Press a key to continue..."
read
}
#
# If you uncomment the debug variable below none of the scripts will be
# executed, just the script name and parameters will be echo'ed to the
# screen so you can see how the scripts are called by rc.
#
# Un-comment the following for debugging.
# debug=echo
#
# Start script or program.
#
startup() {
$debug $*
}
#
# Ignore CTRL-C only in this shell, so we can interrupt subprocesses.
#
trap ":" INT QUIT TSTP
#
# Now find out what the current and what the previous runlevel are. The
# $RUNLEVEL variable is set by init for all it's children. This script
# runs as a child of init.
#
runlevel=$RUNLEVEL
#
# Get first argument. Set new runlevel to this argument. If no runlevel
# was passed to this script we won't change runlevels.
#
[ "$1" != "" ] && runlevel=$1
if [ "$runlevel" = "" ]
then
echo "Usage: $0 <runlevel>" >&2
exit 1
fi
#
# The same goes for $PREVLEVEL (see above for $RUNLEVEL). previous will
# be set to the previous run level. If $PREVLEVEL is not set it means
# that there is no previous runlevel and we'll set previous to N.
#
previous=$PREVLEVEL
[ "$previous" = "" ] && previous=N
export runlevel previous
#
# Is there an rc directory for the new runlevel?
#
if [ -d /etc/rc$runlevel.d ]
then
#
# If so, first collect all the K* scripts in the new run level.
#
if [ $previous != N ]
then
for i in /etc/rc$runlevel.d/K*
do
[ ! -f $i ] && continue
#
# the suffix variable will contain the script name without the leading
# Kxxx
#
suffix=${i#/etc/rc$runlevel.d/K[0-9][0-9][0-9]}
#
# If there is a start script for this K script in the previous runlevel
# determine what it's full path is
#
previous_start=/etc/rc$previous.d/S[0-9][0-9][0-9]$suffix
#
# If there was no previous run level it could be that something was
# started in rcS.d (sysinit level) so we'll determine the path for that
# possibility as well.
#
sysinit_start=/etc/rcS.d/S[0-9][0-9][0-9]$suffix
#
# Stop the service if there is a start script in the previous run level
# or in the sysinit level. If previous_start or sysinit_start do not
# exist the 'continue' command is run which causes the script to abort
# this iteration of the for loop and continue with the next iteration.
# This boils down to that it won't run the commands after the next two
# lines and start over from the top of this for loop. See man bash for
# more info on this.
#
[ ! -f $previous_start ] &&
[ ! -f $sysinit_start ] && continue
#
# If we found previous_start or sysinit_start, run the K script
#
startup $i stop
error_value=$?
#
# If the return value of the script is not 0, something went wrong with
# error checking inside the script. the print_error_msg function will be
# called and the message plus the return value of the K script will be
# printed to the screen
#
if [ $error_value != 0 ]
then
print_error_msg
fi
done
fi
#
# Now run the START scripts for this runlevel.
#
for i in /etc/rc$runlevel.d/S*
do
[ ! -f $i ] && continue
if [ $previous != N ]
then
#
# Find start script in previous runlevel and stop script in this
# runlevel.
#
suffix=${i#/etc/rc$runlevel.d/S[0-9][0-9][0-9]}
stop=/etc/rc$runlevel.d/K[0-9][0-9][0-9]$suffix
previous_start=/etc/rc$previous.d/S[0-9][0-9][0-9]$suffix
#
# If there is a start script in the previous level and no stop script in
# this level, we don't have to re-start the service; abort this
# iteration and start the next one.
#
[ -f $previous_start ] && [ ! -f $stop ] &&
continue
fi
case "$runlevel" in
0|6)
#
# levels 0 and 6 are halt and reboot levels. We don't really start
# anything here so we call with the 'stop' parameter
#
startup $i stop
error_value=$?
#
# If the return value of the script is not 0, something went wrong with
# error checking inside the script. the print_error_msg function will be
# called and the message plus the return value of the K script will be
# printed to the screen
#
if [ $error_value != 0 ]
then
print_error_msg
fi
;;
*)
startup $i start
error_value=$?
#
# If the return value of the script is not 0, something went wrong with
# error checking inside the script. the print_error_msg function will be
# called and the message plus the return value of the K script will be
# printed to the screen
#
if [ $error_value != 0 ]
then
print_error_msg
fi
;;
esac
done
fi
# End /etc/init.d/rc
`EOF`

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