Linux From Scratch
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# Creating the functions script

A new file `/etc/init.d/functions` is created containing the following:

`cat > functions << "EOF"`
#!/bin/sh
# Begin /etc/init.d/functions
#
# Set a few variables that influence the text that's printed on the
# screen. The SET_COL variable starts the text in column number 70 (as
# defined by the COL variable). NORMAL prints text in normal mode.
# SUCCESS prints text in a green colour and FAILURE prints text in a red
# colour
#
COL=70
SET_COL="echo -en \\033[${COL}G"
NORMAL="echo -en \\033[0;39m"
SUCCESS="echo -en \\033[1;32m"
FAILURE="echo -en \\033[1;31m"
#
# The evaluate_retval function evaluates the return value of the process
# that was run just before this function was called. If the return value
# was 0, indicating success, the print_status function is called with
# the 'success' parameter. Otherwise the print_status function is called
# with the failure parameter.
#
evaluate_retval()
{
if [ $? = 0 ]
then
print_status success
else
print_status failure
fi
}
#
# The print_status prints [ OK ] or [FAILED] to the screen. OK appears
# in the colour defined by the SUCCESS variable and FAILED appears in
# the colour defined by the FAILURE variable. Both are printed starting
# in the column defined by the COL variable.
#
print_status()
{
#
# If no parameters are given to the print_status function, print usage
# information.
#
if [ $# = 0 ]
then
echo "Usage: print_status {success|failure}"
return 1
fi
case "$1" in
success)
$SET_COL
echo -n "[ "
$SUCCESS
echo -n "OK"
$NORMAL
echo " ]"
;;
failure)
$SET_COL
echo -n "["
$FAILURE
echo -n "FAILED"
$NORMAL
echo "]"
;;
esac
}
#
# The loadproc function starts a process (often a daemon) with
# proper error checking
#
loadproc()
{
#
# If no parameters are given to the print_status function, print usage
# information.
#
if [ $# = 0 ]
then
echo "Usage: loadproc {program}"
exit 1
fi
#
# Find the basename of the first parameter (the daemon's name without
# the path
# that was provided so /usr/sbin/syslogd becomes plain 'syslogd' after
# basename ran)
#
base=$(/usr/bin/basename $1)
#
# the pidlist variable will contains the output of the pidof command.
# pidof will try to find the PID's that belong to a certain string;
# $base in this case
#
pidlist=$(/bin/pidof -o $$ -o $PPID -o %PPID -x $base)
pid=""
for apid in $pidlist
do
if [ -d /proc/$apid ]
then
pid="$pid $apid"
fi
done
#
# If the $pid variable contains anything (from the previous for loop) it
# means the daemon is already running
#
if [ ! -n "$pid" ]
then
#
# Empty $pid variable means it's not running, so we run $* (all
# parameters giving to this function from the script) and then check the
# return value
#
$*
evaluate_retval
else
#
# The variable $pid was not empty, meaning it was already running. We
# print [FAILED] now
#
print_status failure
fi
}
#
# The killproc function kills a process with proper error checking
#
killproc()
{
#
# If no parameters are given to the print_status function, print usage
# information.
#
if [ $# = 0 ]
then
echo "Usage: killproc {program} [signal]"
exit 1
fi
#
# Find the basename of the first parameter (the daemon's name without
# the path
# that was provided so /usr/sbin/syslogd becomes plain 'syslogd' after
# basename ran)
#
base=$(/usr/bin/basename $1)
#
# Check if we gave a signal to kill the process with (like -HUP, -TERM,
# -KILL, etc) to this function (the second parameter). If no second
# parameter was provided set the nolevel variable. Else set the
# killlevel variable to the value of $2 (the second parameter)
#
if [ "$2" != "" ]
then
killlevel=-$2
else
nolevel=1
fi
#
# the pidlist variable will contains the output of the pidof command.
# pidof will try to find the PID's that belong to a certain string;
# $base in this case
#
pidlist=$(/bin/pidof -o $$ -o $PPID -o %PPID -x $base)
pid=""
for apid in $pidlist
do
if [ -d /proc/$apid ]
then
pid="$pid $apid"
fi
done
#
# If $pid contains something from the previous for loop it means one or
# more PID's were found that belongs to the processes to be killed
#
if [ -n "$pid" ]
then
#
# If no kill level was specified we'll try -TERM first and then sleep
# for 2 seconds to allow the kill to be completed
#
if [ "$nolevel" = 1 ]
then
/bin/kill -TERM $pid
#
# If after -TERM the PID still exists we'll wait 2 seconds before
# trying to kill it with -KILL. If the PID still exist after that, wait
# two more seconds. If the PIDs still exist by then it's safe to assume
# that we cannot kill these PIDs.
#
if /bin/ps h $pid >/dev/null 2>&1
then
/usr/bin/sleep 2
if /bin/ps h $pid > /dev/null 2>&1
then
/bin/kill -KILL $pid
if /bin/ps h $pid > /dev/null 2>&1
then
/usr/bin/sleep 2
fi
fi
fi
/bin/ps h $pid >/dev/null 2>&1
if [ $? = 0 ]
then
#
# If after the -KILL it still exists it can't be killed for some reason
# and we'll print [FAILED]
#
print_status failure
else
#
# It was killed, remove possible stale PID file in /var/run and
# print [ OK ]
#
/bin/rm -f /var/run/$base.pid
print_status success
fi
else
#
# A kill level was provided. Kill with the provided kill level and wait
# for 2 seconds to allow the kill to be completed
#
/bin/kill $killlevel $pid
if /bin/ps h $pid > /dev/null 2>&1
then
/usr/bin/sleep 2
fi
/bin/ps h $pid >/dev/null 2>&1
if [ $? = 0 ]
then
#
# If ps' return value is 0 it means it ran ok which indicates that the
# PID still exists. This means the process wasn't killed properly with
# the signal provided. Print [FAILED]
#
print_status failure
else
#
# If the return value was 1 or higher it means the PID didn't exist
# anymore which means it was killed successfully. Remove possible stale
# PID file and print [ OK ]
#
/bin/rm -f /var/run/$base.pid
print_status success
fi
fi
else
#
# The PID didn't exist so we can't attempt to kill it. Print [FAILED]
#
print_status failure
fi
}
#
# The reloadproc functions sends a signal to a daemon telling it to
# reload it's configuration file. This is almost identical to the
# killproc function with the exception that it won't try to kill it with
# a -KILL signal (aka -9)
#
reloadproc()
{
#
# If no parameters are given to the print_status function, print usage
# information.
#
if [ $# = 0 ]
then
echo "Usage: reloadproc {program} [signal]"
exit 1
fi
#
# Find the basename of the first parameter (the daemon's name without
# the path that was provided so /usr/sbin/syslogd becomes plain 'syslogd'
# after basename ran)
#
base=$(/usr/bin/basename $1)
#
# Check if we gave a signal to send to the process (like -HUP)
# to this function (the second parameter). If no second
# parameter was provided set the nolevel variable. Else set the
# killlevel variable to the value of $2 (the second parameter)
#
if [ -n "$2" ]
then
killlevel=-$2
else
nolevel=1
fi
#
# the pidlist variable will contains the output of the pidof command.
# pidof will try to find the PID's that belong to a certain string;
# $base in this case
#
pidlist=$(/bin/pidof -o $$ -o $PPID -o %PPID -x $base)
pid=""
for apid in $pidlist
do
if [ -d /proc/$apid ]
then
pid="$pid $apid"
fi
done
#
# If $pid contains something from the previous for loop it means one or
# more PID's were found that belongs to the processes to be reloaded
#
if [ -n "$pid" ]
then
#
# If nolevel was set we will use the default reload signal SIGHUP.
#
if [ "$nolevel" = 1 ]
then
/bin/kill -SIGHUP $pid
evaluate_retval
else
#
# Else we will use the provided signal
#
/bin/kill $killlevel $pid
evaluate_retval
fi
else
#
# If $pid is empty no PID's have been found that belong to the process
# and print [FAILED]
#
print_status failure
fi
}
#
# The statusproc function will try to find out if a process is running
# or not
#
statusproc()
{
#
# If no parameters are given to the print_status function, print usage
# information.
#
if [ $# = 0 ]
then
echo "Usage: status {program}"
return 1
fi
#
# $pid will contain a list of PID's that belong to a process
#
pid=$(/bin/pidof -o $$ -o $PPID -o %PPID -x $1)
if [ -n "$pid" ]
then
#
# If $pid contains something, the process is running, print the contents
# of the $pid variable
#
echo "$1 running with Process ID $pid"
return 0
fi
#
# If $pid doesn't contain it check if a PID file exists and inform the
# user about this stale file.
#
if [ -f /var/run/$1.pid ]
then
pid=$(/usr/bin/head -1 /var/run/$1.pid)
if [ -n "$pid" ]
then
echo "$1 not running but /var/run/$1.pid exists"
return 1
fi
else
echo "$1 is not running"
fi
}
# End /etc/init.d/functions
`EOF`

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