mirror of https://github.com/tLDP/LDP
252 lines
6.9 KiB
XML
252 lines
6.9 KiB
XML
<sect1 id="ch07-rc">
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<title>Creating the rc script</title>
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<?dbhtml filename="rc.html" dir="chapter07"?>
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<para>The first main boot script is the <filename>/etc/init.d/rc</filename>
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script. Create the <filename>/etc/init.d/rc</filename> script by running the
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following command:</para>
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<para><screen><userinput>cat > /etc/init.d/rc << "EOF"</userinput>
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#!/bin/sh
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# Begin /etc/init.d/rc
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#
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# By Jason Pearce - jason.pearce@linux.org
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# Modified by Gerard Beekmans - gerard@linuxfromscratch.org
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# print_error_msg based on ideas by Simon Perreault -
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# nomis80@videotron.ca
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#
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#
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# Include the functions declared in the /etc/init.d/functions file
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#
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source /etc/init.d/functions
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#
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# The print_error_msg function prints an error message when an unforeseen
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# error occurred that wasn't trapped for some reason by a evaluate_retval
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# call or error checking in different ways.
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print_error_msg()
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{
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echo
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$FAILURE
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echo -n "You should not read this error message. It means "
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echo "that an unforeseen error "
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echo -n "took place and subscript $i exited with "
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echo "a return value "
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echo -n "of $error_value for an unknown reason. If you're able "
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echo "to trace this error down "
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echo -n "to a bug in one of the files provided by this book, "
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echo "please be so kind to "
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echo -n "inform us at lfs-dev@linuxfromscratch.org"
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$NORMAL
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echo
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echo
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echo "Press a key to continue..."
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read
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}
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#
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# If you uncomment the debug variable below none of the scripts will be
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# executed, just the script name and parameters will be echo'ed to the
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# screen so you can see how the scripts are called by rc.
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#
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# Un-comment the following for debugging.
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# debug=echo
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#
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# Start script or program.
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#
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startup() {
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$debug "$@"
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}
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#
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# Ignore CTRL-C only in this shell, so we can interrupt subprocesses.
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#
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trap ":" INT QUIT TSTP
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#
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# Now find out what the current and what the previous runlevel are. The
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# $RUNLEVEL variable is set by init for all it's children. This script
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# runs as a child of init.
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#
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runlevel=$RUNLEVEL
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#
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# Get first argument. Set new runlevel to this argument. If no runlevel
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# was passed to this script we won't change runlevels.
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#
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[ "$1" != "" ] && runlevel=$1
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if [ "$runlevel" = "" ]
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then
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echo "Usage: $0 <runlevel>" >&2
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exit 1
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fi
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#
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# The same goes for $PREVLEVEL (see above for $RUNLEVEL). previous will
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# be set to the previous run level. If $PREVLEVEL is not set it means
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# that there is no previous runlevel and we'll set previous to N.
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#
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previous=$PREVLEVEL
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[ "$previous" = "" ] && previous=N
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export runlevel previous
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#
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# Is there an rc directory for the new runlevel?
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#
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if [ -d /etc/rc$runlevel.d ]
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then
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#
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# If so, first collect all the K* scripts in the new run level.
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#
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if [ $previous != N ]
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then
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for i in /etc/rc$runlevel.d/K*
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do
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[ ! -f $i ] && continue
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#
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# the suffix variable will contain the script name without the leading
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# Kxxx
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#
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suffix=${i#/etc/rc$runlevel.d/K[0-9][0-9][0-9]}
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#
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# If there is a start script for this K script in the previous runlevel
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# determine what it's full path is
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#
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previous_start=/etc/rc$previous.d/S[0-9][0-9][0-9]$suffix
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#
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# If there was no previous run level it could be that something was
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# started in rcS.d (sysinit level) so we'll determine the path for that
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# possibility as well.
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#
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sysinit_start=/etc/rcS.d/S[0-9][0-9][0-9]$suffix
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#
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# Stop the service if there is a start script in the previous run level
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# or in the sysinit level. If previous_start or sysinit_start do not
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# exist the 'continue' command is run which causes the script to abort
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# this iteration of the for loop and continue with the next iteration.
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# This boils down to that it won't run the commands after the next two
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# lines and start over from the top of this for loop. See man bash for
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# more info on this.
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#
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[ ! -f $previous_start ] &&
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[ ! -f $sysinit_start ] && continue
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#
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# If we found previous_start or sysinit_start, run the K script
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#
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startup $i stop
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error_value=$?
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#
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# If the return value of the script is not 0, something went wrong with
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# error checking inside the script. the print_error_msg function will be
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# called and the message plus the return value of the K script will be
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# printed to the screen
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#
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if [ $error_value != 0 ]
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then
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print_error_msg
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fi
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done
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fi
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#
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# Now run the START scripts for this runlevel.
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#
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for i in /etc/rc$runlevel.d/S*
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do
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[ ! -f $i ] && continue
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if [ $previous != N ]
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then
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#
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# Find start script in previous runlevel and stop script in this
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# runlevel.
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#
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suffix=${i#/etc/rc$runlevel.d/S[0-9][0-9][0-9]}
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stop=/etc/rc$runlevel.d/K[0-9][0-9][0-9]$suffix
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previous_start=/etc/rc$previous.d/S[0-9][0-9][0-9]$suffix
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#
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# If there is a start script in the previous level and no stop script in
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# this level, we don't have to re-start the service; abort this
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# iteration and start the next one.
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#
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[ -f $previous_start ] && [ ! -f $stop ] &&
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continue
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fi
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case "$runlevel" in
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0|6)
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#
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# levels 0 and 6 are halt and reboot levels. We don't really start
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# anything here so we call with the 'stop' parameter
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#
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startup $i stop
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error_value=$?
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#
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# If the return value of the script is not 0, something went wrong with
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# error checking inside the script. the print_error_msg function will be
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# called and the message plus the return value of the K script will be
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# printed to the screen
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#
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if [ $error_value != 0 ]
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then
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print_error_msg
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fi
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;;
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*)
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startup $i start
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error_value=$?
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#
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# If the return value of the script is not 0, something went wrong with
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# error checking inside the script. the print_error_msg function will be
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# called and the message plus the return value of the K script will be
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# printed to the screen
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#
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if [ $error_value != 0 ]
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then
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print_error_msg
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fi
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;;
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esac
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done
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fi
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# End /etc/init.d/rc
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<userinput>EOF</userinput></screen></para>
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</sect1>
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