mirror of https://github.com/tLDP/LDP
507 lines
12 KiB
XML
507 lines
12 KiB
XML
<sect1 id="ch07-functions">
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<title>Creating the functions script</title>
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<?dbhtml filename="functions.html" dir="chapter07"?>
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<para>Create the <filename>/etc/init.d/functions</filename> script by running
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the following command:</para>
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<para><screen><userinput>cat > /etc/init.d/functions << "EOF"</userinput>
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#!/bin/sh
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# Begin /etc/init.d/functions
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#
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# Set a few variables that influence the text that's printed on the
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# screen. The SET_COL variable starts the text in the column number
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# decided by the COL and WCOL section (as defined by the COL
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# variable). NORMAL prints text in normal mode.
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# SUCCESS prints text in a green colour and FAILURE prints text in a red
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# colour
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#
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# If COLUMNS hasn't been set yet (bash sets it but not when called as
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# sh), do it ourself
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if [ -z "$COLUMNS" ]
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then
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# Get the console device if we don't have it already
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# This is ok by the FHS as there is a fallback if
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# /usr/bin/tty isn't available, for example at bootup.
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test -x /usr/bin/tty && CONSOLE=`/usr/bin/tty`
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test -z "$CONSOLE" && CONSOLE=/dev/console
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# Get the console size (rows columns)
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SIZE=$(stty size < $CONSOLE)
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# Strip off the rows leaving the columns
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COLUMNS=${SIZE#*\ }
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fi
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COL=$[$COLUMNS - 10]
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WCOL=$[$COLUMNS - 30]
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SET_COL="echo -en \\033[${COL}G"
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SET_WCOL="echo -en \\033[${WCOL}G"
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NORMAL="echo -en \\033[0;39m"
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SUCCESS="echo -en \\033[1;32m"
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WARNING="echo -en \\033[1;33m"
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FAILURE="echo -en \\033[1;31m"
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#
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# The evaluate_retval function evaluates the return value of the process
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# that was run just before this function was called. If the return value
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# was 0, indicating success, the print_status function is called with
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# the 'success' parameter. Otherwise the print_status function is called
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# with the failure parameter.
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#
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evaluate_retval()
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{
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if [ $? = 0 ]
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then
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print_status success
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else
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print_status failure
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fi
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}
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#
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# The print_status prints [ OK ] or [FAILED] to the screen. OK appears
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# in the colour defined by the SUCCESS variable and FAILED appears in
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# the colour defined by the FAILURE variable. Both are printed starting
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# in the column defined by the COL variable.
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#
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print_status()
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{
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#
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# If no parameters are given to the print_status function, print usage
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# information.
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#
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if [ $# = 0 ]
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then
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echo "Usage: print_status {success|failure}"
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return 1
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fi
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case "$1" in
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success)
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$SET_COL
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echo -n "[ "
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$SUCCESS
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echo -n "OK"
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$NORMAL
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echo " ]"
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;;
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warning)
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$SET_COL
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echo -n "[ "
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$WARNING
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echo -n "ATTN"
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$NORMAL
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echo " ]"
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;;
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failure)
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$SET_COL
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echo -n "["
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$FAILURE
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echo -n "FAILED"
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$NORMAL
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echo "]"
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;;
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esac
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}
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#
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# The loadproc function starts a process (often a daemon) with
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# proper error checking
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#
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loadproc()
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{
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#
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# If no parameters are given to the print_status function, print usage
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# information.
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#
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if [ $# = 0 ]
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then
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echo "Usage: loadproc {program}"
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exit 1
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fi
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#
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# Find the basename of the first parameter (the daemon's name without
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# the path
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# that was provided so /usr/sbin/syslogd becomes plain 'syslogd' after
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# basename ran)
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#
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base=$(/usr/bin/basename $1)
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#
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# the pidlist variable will contains the output of the pidof command.
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# pidof will try to find the PID's that belong to a certain string;
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# $base in this case
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#
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pidlist=$(/bin/pidof -o $$ -o $PPID -o %PPID -x $base)
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pid=""
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for apid in $pidlist
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do
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if [ -d /proc/$apid ]
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then
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pid="$pid $apid"
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fi
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done
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#
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# If the $pid variable contains anything (from the previous for loop) it
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# means the daemon is already running
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#
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if [ ! -n "$pid" ]
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then
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#
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# Empty $pid variable means it's not running, so we run "$@" (all
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# parameters giving to this function from the script) and then check the
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# return value
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#
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"$@"
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evaluate_retval
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else
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#
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# The variable $pid was not empty, meaning it was already running. We'll
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# print [ ATTN ] now
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#
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$SET_WCOL
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echo -n "Already running"
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print_status warning
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fi
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}
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#
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# The killproc function kills a process with proper error checking
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#
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killproc()
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{
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#
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# If no parameters are given to the print_status function, print usage
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# information.
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#
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if [ $# = 0 ]
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then
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echo "Usage: killproc {program} [signal]"
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exit 1
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fi
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#
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# Find the basename of the first parameter (the daemon's name without
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# the path
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# that was provided so /usr/sbin/syslogd becomes plain 'syslogd' after
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# basename ran)
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#
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base=$(/usr/bin/basename $1)
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#
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# Check if we gave a signal to kill the process with (like -HUP, -TERM,
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# -KILL, etc) to this function (the second parameter). If no second
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# parameter was provided set the nolevel variable. Else set the
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# killlevel variable to the value of $2 (the second parameter)
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#
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if [ "$2" != "" ]
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then
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killlevel=-$2
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else
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nolevel=1
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fi
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#
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# the pidlist variable will contains the output of the pidof command.
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# pidof will try to find the PID's that belong to a certain string;
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# $base in this case
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#
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pidlist=$(/bin/pidof -o $$ -o $PPID -o %PPID -x $base)
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pid=""
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for apid in $pidlist
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do
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if [ -d /proc/$apid ]
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then
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pid="$pid $apid"
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fi
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done
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#
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# If $pid contains something from the previous for loop it means one or
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# more PID's were found that belongs to the processes to be killed
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#
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if [ -n "$pid" ]
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then
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#
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# If no kill level was specified we'll try -TERM first and then sleep
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# for 2 seconds to allow the kill to be completed
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#
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if [ "$nolevel" = 1 ]
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then
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/bin/kill -TERM $pid
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#
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# If after -TERM the PID still exists we'll wait 2 seconds before
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# trying to kill it with -KILL. If the PID still exist after that, wait
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# two more seconds. If the PIDs still exist by then it's safe to assume
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# that we cannot kill these PIDs.
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#
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if /bin/ps h $pid >/dev/null 2>&1
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then
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/usr/bin/sleep 2
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if /bin/ps h $pid > /dev/null 2>&1
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then
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/bin/kill -KILL $pid
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if /bin/ps h $pid > /dev/null 2>&1
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then
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/usr/bin/sleep 2
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fi
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fi
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fi
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/bin/ps h $pid >/dev/null 2>&1
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if [ $? = 0 ]
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then
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#
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# If after the -KILL it still exists it can't be killed for some reason
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# and we'll print [FAILED]
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#
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print_status failure
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else
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#
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# It was killed, remove possible stale PID file in /var/run and
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# print [ OK ]
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#
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/bin/rm -f /var/run/$base.pid
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print_status success
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fi
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else
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#
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# A kill level was provided. Kill with the provided kill level and wait
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# for 2 seconds to allow the kill to be completed
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#
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/bin/kill $killlevel $pid
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if /bin/ps h $pid > /dev/null 2>&1
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then
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/usr/bin/sleep 2
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fi
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/bin/ps h $pid >/dev/null 2>&1
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if [ $? = 0 ]
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then
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#
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# If ps' return value is 0 it means it ran ok which indicates that the
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# PID still exists. This means the process wasn't killed properly with
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# the signal provided. Print [FAILED]
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#
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print_status failure
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else
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#
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# If the return value was 1 or higher it means the PID didn't exist
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# anymore which means it was killed successfully. Remove possible stale
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# PID file and print [ OK ]
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#
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/bin/rm -f /var/run/$base.pid
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print_status success
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fi
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fi
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else
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#
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# The PID didn't exist so we can't attempt to kill it. Print [ ATTN ]
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#
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$SET_WCOL
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echo -n "Not running"
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print_status warning
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fi
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}
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#
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# The reloadproc functions sends a signal to a daemon telling it to
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# reload it's configuration file. This is almost identical to the
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# killproc function with the exception that it won't try to kill it with
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# a -KILL signal (aka -9)
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#
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reloadproc()
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{
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#
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# If no parameters are given to the print_status function, print usage
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# information.
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#
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if [ $# = 0 ]
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then
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echo "Usage: reloadproc {program} [signal]"
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exit 1
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fi
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#
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# Find the basename of the first parameter (the daemon's name without
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# the path that was provided so /usr/sbin/syslogd becomes plain 'syslogd'
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# after basename ran)
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#
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base=$(/usr/bin/basename $1)
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#
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# Check if we gave a signal to send to the process (like -HUP)
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# to this function (the second parameter). If no second
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# parameter was provided set the nolevel variable. Else set the
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# killlevel variable to the value of $2 (the second parameter)
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#
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if [ -n "$2" ]
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then
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killlevel=-$2
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else
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nolevel=1
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fi
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#
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# the pidlist variable will contains the output of the pidof command.
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# pidof will try to find the PID's that belong to a certain string;
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# $base in this case
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#
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pidlist=$(/bin/pidof -o $$ -o $PPID -o %PPID -x $base)
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pid=""
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for apid in $pidlist
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do
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if [ -d /proc/$apid ]
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then
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pid="$pid $apid"
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fi
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done
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#
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# If $pid contains something from the previous for loop it means one or
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# more PID's were found that belongs to the processes to be reloaded
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#
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if [ -n "$pid" ]
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then
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#
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# If nolevel was set we will use the default reload signal SIGHUP.
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#
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if [ "$nolevel" = 1 ]
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then
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/bin/kill -SIGHUP $pid
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evaluate_retval
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else
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#
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# Else we will use the provided signal
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#
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/bin/kill $killlevel $pid
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evaluate_retval
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fi
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else
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#
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# If $pid is empty no PID's have been found that belong to the process.
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# Print [ ATTN ]
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#
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$SET_WCOL
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echo -n "Not running"
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print_status warning
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fi
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}
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#
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# The statusproc function will try to find out if a process is running
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# or not
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#
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statusproc()
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{
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#
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# If no parameters are given to the print_status function, print usage
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# information.
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#
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if [ $# = 0 ]
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then
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echo "Usage: status {program}"
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return 1
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fi
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#
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# $pid will contain a list of PID's that belong to a process
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#
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pid=$(/bin/pidof -o $$ -o $PPID -o %PPID -x $1)
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if [ -n "$pid" ]
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then
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#
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# If $pid contains something, the process is running, print the contents
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# of the $pid variable
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#
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echo "$1 running with Process ID $pid"
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return 0
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fi
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#
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# If $pid doesn't contain it check if a PID file exists and inform the
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# user about this stale file.
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#
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if [ -f /var/run/$1.pid ]
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then
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pid=$(/usr/bin/head -1 /var/run/$1.pid)
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if [ -n "$pid" ]
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then
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echo "$1 not running but /var/run/$1.pid exists"
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return 1
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fi
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else
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echo "$1 is not running"
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fi
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}
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# End /etc/init.d/functions
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<userinput>EOF</userinput></screen></para>
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|
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</sect1>
|
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|