Re: segmentation fault?? and fsck problems.

["L. C. Robinson" <lcr@draken.localnet>]

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On Wed, 10 Jun 1998, John Covici wrote:

> I didn't want to redirect the whole sysinit process because I had
> already put in those echo statements and didn't want to confuse things
> further.  Also, I want the screens to remain the same in case
> something else goes wrong where I need sighted assistance.

You probably just need to do:
fsck [options]   > /dev/ttyS0 
or something similar.  I tried doing:
exec > /dev/tty6 2> /dev/tty6 < /dev/tty6
fsck -fV /dev/hdc2
and it worked in interactive mode (hdc2 is a small experimental
partition I use).
fsck -fV /dev/hdc2 > /dev/tty6 2> /dev/tty6 < /dev/tty6
worked similarly.
If that doesn't work, there are other sneaky ways to save the
output in a buffer or coprocess for later logging or reading.

BTW, I have no difficulty remounting this partition read only,
unless there is a file open on it.  

> >The drop to single user shell (sulogin) could be disabled, or you
> >could just type ^D when that happens, to continue on, as the
> >prompt directs (I guess you would have to do this without seeing
> >the prompt?).  But this won't happen if you make sure to use
> >the -a option to fsck, and if it does happen, it may just
> >mean you tried to redirect the interactive output, in which
> >case you have effectively made fsck inoperative (bad).
> 
> But what I really would like to do, if I get that shell I would like
> to run screader or whatever I am using and find out what is happening.

I just checked the sulogin man page, and you are in luck!!  You
can add a tty device argument to sulogin, to redirect to your speech
device, or whatever, and you can even add a timeout, and control
what shell is used.
 
> >> I have modified the bootup scripts so that there are extra echo
> >> statements redirected to the synthesizer so I have some idea of
> >> what is happening.
> >
> >But the echo statements only tell you whether the daemons tried
> >to start, not whether they succeeded.  My modifications to the
> >"functions" script change all that.
> 
> Well, some of them do test return codes, but I'd like to see your mods
> and maybe get some ideas from them.

I will attach my functions script.  Be sure to read the commentary:
it tells you to add some lines to another script or two.

> >> By closing down all the loggers, lpd, cron and a couple of
> >> other processes, I think I can do a safe fsck in read/write
> >> mode -- at least I tried it a couple of times and got no
> >> errors.
> >
> >Sounds pretty risky to me.  If you can't remount it read only, it
> >means you missed some process still writing to the filesystem.
> 
> But maybe its only screader which has something open in read/write
> mode and isn't doing any actual writing.

I doubt it, but fuser can tell you for sure.  There are better ways,
though.  If you do this, eventually you will overlook something 
during a check, and damage your filesystem.  Then there is the
problem of getting all the daemons properly restarted.  That's
what single user mode is for (but it may be broken, as I
mentioned -- ie, you would need to customize it).
 
-- 
L. C. Robinson
reply to infynity@cyberhighway.net (a family account)

People buy MicroShaft for compatibility, but get incompatibility and
instability instead: then they get to buy upgrades to fix it, and get
still more problems.  This is award winning "innovation".


[-- Attachment #2: /etc/RC.D/init.d/functions --]
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#! /bin/sh
#
# functions	This file contains functions to be used by most or all
#		shell scripts in the /etc/init.d directory.
#
# Version:	@(#) /etc/init.d/functions 1.01 26-Oct-1993
#
# Author:	Miquel van Smoorenburg, <miquels@drinkel.nl.mugnet.org>
# Hacked by:    Greg Galloway and Marc Ewing
#

# First set up a default search path.
export PATH="/sbin:/usr/sbin:/bin:/usr/bin"

# Customize for local use:
: set ${LOG_TTY:=/dev/tty12} to where you want messages sent -- should match syslog.conf
SKIP_AWK=true
# VERBOSE_BOOTUP=true       # uncomment to make bootup stuff echo to screen
DAEMON_LOG=/var/log/init_daemons  # set local3.info to go here in /etc/syslog.conf
: ${DAEMON_LOG:-/var/log/messages}  default set here if not set already
# Put the following at the end of /etc/RC.D/rc 
# ${VERBOSE_BOOTUP:-echo "Quiet bootup: see $DAEMON_LOG for deamon startup messages."}
FAILED_DAEMON_MSG="\nWARNING: some daemon(s) failed to start: see the log file!!\n" 

# Use ONLY for machines with no monitor (serial terminal control)
# SERIAL_CONSOLE=/dev/ttyS0

# set -x
MyTTY=`/usr/bin/tty`
case "$MyTTY" in
/dev/tty?|/dev/conso*|/dev/tty)
	# exec < $NEWTTY > $NEWTTY 2> $NEWTTY
	unset SERIAL_CONSOLE
	;;
not*) : ;;
/dev/ttyS?) SERIAL_CONSOLE=/dev/ttyS0 ;;
esac
set +x

# I note that 'logger' and 'basename' are in /usr/bin, and may not be available
# on a small root only filesystem...
# basename can be replaced with a (limited) shell function:
basename(){ builtin echo "${1##*/}" ; }

# A function to start a program.
daemon() {
	# Test syntax.
	if [ $# = 0 ]; then
		echo "Usage: daemon {program}"
		return 1
	fi

	# Save basename.
	base=`basename $1`

	# See if it's already running.
	[ "`pidofproc $base`" != "" ] && return

	# And start it up (with error logging):
	[ "${VERBOSE_BOOTUP}" ] || builtin echo -n .
	run_prog "$@"
}

run_prog(){
	base=`basename $1`
	"$@" ||
	if [ "`pidofproc $base`" = "" ] ; then
		shift
		VERBOSE_BOOTUP=error Logger "${ST_MSG:=Start of} $base $* *** FAILED ****" 
		touch /tmp/FAILED_DAEMON_MARKER
		return 1
	fi
	shift
	Logger "${ST_MSG:=Started} $base $*" 
}

echo(){
	# Converts messages of the form: echo -n "Starting XXX: " for the Logger function
	# or alternately: echo -n "Shutting down XXX services: "
	if [ "$#" = 0 -a "$ECHO" ]; then
		# for the terminating echo in converted statements
		# Do only if logger ran (ST_MSG is reset):
		[ "$ST_MSG" = ' ' ] && builtin echo
		unset ST_MSG ECHO LOG_MSG
	#elif [ "X${1}" = X-n -a \( "X${2#Shutting}" != "X$2" -o "X${2#Starting}" != "X$2" \) ]
	elif [ "X${1}" = X-n ] ; then
		case "$2" in
			Shutting*|Starting*|Stopping*)
				ST_MSG="$2" ECHO="builtin echo" # save it for "Logger" function
				;;
			# For normal echo statements:
			*) builtin echo "$@" ;;
		esac
	else
		# For normal echo statements:
		if [ "$SERIAL_CONSOLE" ] ; then
		  builtin echo "$@" > $SERIAL_CONSOLE
		else
			builtin echo "$@"
		fi
	fi
}

Logger(){
  declare LOGGER_TAG="-t daemon"
	if [ "$ECHO" -a "${VERBOSE_BOOTUP}" ]; then
		# For old message compatibility:
		builtin echo -n "$@"
		# unset	LOG_MSG
		logger -p local3.info $LOGGER_TAG "${LOG_MSG}$*"
		[ "$ST_MSG" = ' ' ] || LOG_MSG="$ST_MSG "
		ST_MSG=' '
	else
		# builtin echo actual mesg is: $*
		logger -p local3.info $LOGGER_TAG ${VERBOSE_BOOTUP:+-s} "$*"
		unset ST_MSG
	fi
	no_syslog_echo "$*"
}

no_syslog_echo(){
	# logging doesn't work until syslogd is running, so we do it "manually"
	[ -f /var/lock/subsys/syslog ] && return 0
	builtin echo "syslog off: $*" >> /var/log/init_daemons 
	builtin echo "syslog off: $*" >> ${LOG_TTY:=/dev/tty12}
	return 1
}

# A function to stop a program.
killproc() {
	# Test syntax.
	if [ $# = 0 ]; then
		echo "Usage: killproc {program}"
		return 1
	fi

	# Save basename.
	base=`basename $1`

	# Find pid.
	pid=`pidofproc $base`

	# Kill it.
	if [ "$pid" != "" ] ; then
		if kill -9 $pid
		then
			Logger "${ST_MSG:=Killed} $base" 
		else
			Logger "Kill of $base *** FAILED ****" 
		fi
	fi

	# Remove pid file if any.
	rm -f /var/run/$base.pid
}

# A function to find the pid of a program.
pidofproc() {
	# Test syntax.
	if [ $# = 0 ] ; then
		echo "Usage: pidofproc {program}"
		return 1
	fi

	# First try "pidof"
	type pidof > /dev/null 2>&1 && {
		pid=`pidof $1`
		if [ "$pid" != "" ] ; then
						builtin echo $pid
						return 0
		fi
	}

	# Next try "/var/run/*.pid" files
	type head > /dev/null 2>&1 &&
	if [ -f /var/run/$1.pid ] ; then
					pid=`head -1 /var/run/$1.pid`
					if [ "$pid" != "" ] ; then
									builtin echo $pid
									return 0
					fi
	fi

	# To speed things up:
	[ "$SKIP_AWK" ] && return

	type awk > /dev/null 2>&1 || return
	type ps > /dev/null 2>&1 || return
	# Finally try to extract it from ps
	ps auxw | awk 'BEGIN { prog=ARGV[1]; ARGC=1 } 
			   { if ((prog == $11) || (("(" prog ")") == $11) ||
			   ((prog ":") == $11)) { print $2 } }' $1
}