1 | <sect1 id="ch07-functions">
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2 | <title>Creating the functions script</title>
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3 | <?dbhtml filename="functions.html" dir="chapter07"?>
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4 |
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5 | <para>Create the <filename>/etc/init.d/functions</filename> script by running
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6 | the following command:</para>
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7 |
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8 | <para><screen><userinput>cat > /etc/init.d/functions << "EOF"</userinput>
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9 | #!/bin/sh
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10 | # Begin /etc/init.d/functions
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11 |
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12 | #
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13 | # Set a few variables that influence the text that's printed on the
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14 | # screen. The SET_COL variable starts the text in the column number
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15 | # decided by the COL and WCOL section (as defined by the COL
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16 | # variable). NORMAL prints text in normal mode.
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17 | # SUCCESS prints text in a green colour and FAILURE prints text in a red
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18 | # colour
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19 | #
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20 |
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21 | # If COLUMNS hasn't been set yet (bash sets it but not when called as
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22 | # sh), do it ourself
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23 |
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24 | if [ -z "$COLUMNS" ]
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25 | then
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26 | # Get the console device if we don't have it already
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27 | # This is ok by the FHS as there is a fallback if
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28 | # /usr/bin/tty isn't available, for example at bootup.
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29 | test -x /usr/bin/tty && CONSOLE=`/usr/bin/tty`
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30 | test -z "$CONSOLE" && CONSOLE=/dev/console
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31 |
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32 | # Get the console size (rows columns)
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33 | SIZE=$(stty size < $CONSOLE)
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34 |
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35 | # Strip off the rows leaving the columns
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36 | COLUMNS=${SIZE#*\ }
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37 | fi
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38 |
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39 | COL=$[$COLUMNS - 10]
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40 | WCOL=$[$COLUMNS - 30]
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41 | SET_COL="echo -en \\033[${COL}G"
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42 | SET_WCOL="echo -en \\033[${WCOL}G"
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43 | NORMAL="echo -en \\033[0;39m"
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44 | SUCCESS="echo -en \\033[1;32m"
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45 | WARNING="echo -en \\033[1;33m"
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46 | FAILURE="echo -en \\033[1;31m"
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47 |
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48 | #
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49 | # The evaluate_retval function evaluates the return value of the process
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50 | # that was run just before this function was called. If the return value
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51 | # was 0, indicating success, the print_status function is called with
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52 | # the 'success' parameter. Otherwise the print_status function is called
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53 | # with the failure parameter.
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54 | #
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55 |
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56 | evaluate_retval()
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57 | {
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58 | if [ $? = 0 ]
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59 | then
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60 | print_status success
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61 | else
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62 | print_status failure
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63 | fi
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64 | }
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65 |
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66 | #
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67 | # The print_status prints [ OK ] or [FAILED] to the screen. OK appears
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68 | # in the colour defined by the SUCCESS variable and FAILED appears in
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69 | # the colour defined by the FAILURE variable. Both are printed starting
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70 | # in the column defined by the COL variable.
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71 | #
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72 |
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73 | print_status()
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74 | {
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75 |
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76 | #
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77 | # If no parameters are given to the print_status function, print usage
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78 | # information.
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79 | #
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80 |
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81 | if [ $# = 0 ]
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82 | then
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83 | echo "Usage: print_status {success|failure}"
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84 | return 1
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85 | fi
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86 |
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87 | case "$1" in
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88 | success)
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89 | $SET_COL
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90 | echo -n "[ "
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91 | $SUCCESS
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92 | echo -n "OK"
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93 | $NORMAL
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94 | echo " ]"
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95 | ;;
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96 | warning)
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97 | $SET_COL
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98 | echo -n "[ "
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99 | $WARNING
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100 | echo -n "ATTN"
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101 | $NORMAL
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102 | echo " ]"
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103 | ;;
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104 | failure)
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105 | $SET_COL
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106 | echo -n "["
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107 | $FAILURE
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108 | echo -n "FAILED"
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109 | $NORMAL
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110 | echo "]"
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111 | ;;
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112 | esac
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113 |
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114 | }
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115 |
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116 | #
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117 | # The loadproc function starts a process (often a daemon) with
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118 | # proper error checking
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119 | #
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120 |
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121 | loadproc()
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122 | {
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123 |
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124 | #
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125 | # If no parameters are given to the print_status function, print usage
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126 | # information.
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127 | #
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128 |
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129 | if [ $# = 0 ]
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130 | then
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131 | echo "Usage: loadproc {program}"
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132 | exit 1
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133 | fi
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134 | #
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135 | # Find the basename of the first parameter (the daemon's name without
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136 | # the path
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137 | # that was provided so /usr/sbin/syslogd becomes plain 'syslogd' after
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138 | # basename ran)
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139 | #
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140 |
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141 | base=$(/usr/bin/basename $1)
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142 | #
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143 | # the pidlist variable will contains the output of the pidof command.
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144 | # pidof will try to find the PID's that belong to a certain string;
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145 | # $base in this case
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146 | #
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147 |
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148 | pidlist=$(/bin/pidof -o $$ -o $PPID -o %PPID -x $base)
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149 |
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150 | pid=""
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151 |
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152 | for apid in $pidlist
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153 | do
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154 | if [ -d /proc/$apid ]
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155 | then
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156 | pid="$pid $apid"
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157 | fi
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158 | done
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159 | #
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160 | # If the $pid variable contains anything (from the previous for loop) it
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161 | # means the daemon is already running
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162 | #
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163 |
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164 | if [ ! -n "$pid" ]
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165 | then
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166 | #
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167 | # Empty $pid variable means it's not running, so we run "$@" (all
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168 | # parameters giving to this function from the script) and then check the
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169 | # return value
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170 | #
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171 |
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172 | "$@"
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173 | evaluate_retval
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174 | else
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175 | #
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176 | # The variable $pid was not empty, meaning it was already running. We'll
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177 | # print [ ATTN ] now
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178 | #
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179 |
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180 | $SET_WCOL
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181 | echo -n "Already running"
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182 | print_status warning
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183 | fi
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184 |
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185 | }
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186 |
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187 | #
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188 | # The killproc function kills a process with proper error checking
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189 | #
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190 |
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191 | killproc()
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192 | {
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193 |
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194 | #
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195 | # If no parameters are given to the print_status function, print usage
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196 | # information.
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197 | #
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198 |
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199 | if [ $# = 0 ]
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200 | then
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201 | echo "Usage: killproc {program} [signal]"
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202 | exit 1
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203 | fi
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204 |
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205 | #
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206 | # Find the basename of the first parameter (the daemon's name without
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207 | # the path
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208 | # that was provided so /usr/sbin/syslogd becomes plain 'syslogd' after
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209 | # basename ran)
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210 | #
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211 |
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212 | base=$(/usr/bin/basename $1)
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213 |
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214 | #
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215 | # Check if we gave a signal to kill the process with (like -HUP, -TERM,
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216 | # -KILL, etc) to this function (the second parameter). If no second
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217 | # parameter was provided set the nolevel variable. Else set the
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218 | # killlevel variable to the value of $2 (the second parameter)
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219 | #
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220 |
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221 | if [ "$2" != "" ]
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222 | then
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223 | killlevel=-$2
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224 | else
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225 | nolevel=1
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226 | fi
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227 |
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228 | #
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229 | # the pidlist variable will contains the output of the pidof command.
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230 | # pidof will try to find the PID's that belong to a certain string;
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231 | # $base in this case
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232 | #
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233 |
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234 | pidlist=$(/bin/pidof -o $$ -o $PPID -o %PPID -x $base)
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235 |
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236 | pid=""
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237 |
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238 | for apid in $pidlist
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239 | do
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240 | if [ -d /proc/$apid ]
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241 | then
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242 | pid="$pid $apid"
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243 | fi
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244 | done
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245 |
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246 | #
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247 | # If $pid contains something from the previous for loop it means one or
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248 | # more PID's were found that belongs to the processes to be killed
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249 | #
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250 |
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251 | if [ -n "$pid" ]
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252 | then
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253 |
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254 | #
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255 | # If no kill level was specified we'll try -TERM first and then sleep
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256 | # for 2 seconds to allow the kill to be completed
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257 | #
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258 |
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259 | if [ "$nolevel" = 1 ]
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260 | then
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261 | /bin/kill -TERM $pid
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262 |
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263 | #
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264 | # If after -TERM the PID still exists we'll wait 2 seconds before
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265 | # trying to kill it with -KILL. If the PID still exist after that, wait
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266 | # two more seconds. If the PIDs still exist by then it's safe to assume
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267 | # that we cannot kill these PIDs.
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268 | #
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269 |
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270 | if /bin/ps h $pid >/dev/null 2>&1
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271 | then
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272 | /usr/bin/sleep 2
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273 | if /bin/ps h $pid > /dev/null 2>&1
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274 | then
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275 | /bin/kill -KILL $pid
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276 | if /bin/ps h $pid > /dev/null 2>&1
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277 | then
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278 | /usr/bin/sleep 2
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279 | fi
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280 | fi
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281 | fi
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282 | /bin/ps h $pid >/dev/null 2>&1
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283 | if [ $? = 0 ]
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284 | then
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285 | #
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286 | # If after the -KILL it still exists it can't be killed for some reason
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287 | # and we'll print [FAILED]
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288 | #
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289 |
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290 | print_status failure
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291 | else
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292 |
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293 | #
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294 | # It was killed, remove possible stale PID file in /var/run and
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295 | # print [ OK ]
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296 | #
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297 |
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298 | /bin/rm -f /var/run/$base.pid
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299 | print_status success
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300 | fi
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301 | else
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302 |
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303 | #
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304 | # A kill level was provided. Kill with the provided kill level and wait
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305 | # for 2 seconds to allow the kill to be completed
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306 | #
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307 |
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308 | /bin/kill $killlevel $pid
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309 | if /bin/ps h $pid > /dev/null 2>&1
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310 | then
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311 | /usr/bin/sleep 2
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312 | fi
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313 | /bin/ps h $pid >/dev/null 2>&1
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314 | if [ $? = 0 ]
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315 | then
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316 |
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317 | #
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318 | # If ps' return value is 0 it means it ran ok which indicates that the
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319 | # PID still exists. This means the process wasn't killed properly with
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320 | # the signal provided. Print [FAILED]
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321 | #
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322 |
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323 | print_status failure
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324 | else
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325 |
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326 | #
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327 | # If the return value was 1 or higher it means the PID didn't exist
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328 | # anymore which means it was killed successfully. Remove possible stale
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329 | # PID file and print [ OK ]
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330 | #
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331 |
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332 | /bin/rm -f /var/run/$base.pid
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333 | print_status success
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334 | fi
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335 | fi
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336 | else
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337 |
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338 | #
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339 | # The PID didn't exist so we can't attempt to kill it. Print [ ATTN ]
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340 | #
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341 |
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342 | $SET_WCOL
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343 | echo -n "Not running"
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344 | print_status warning
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345 | fi
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346 | }
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347 |
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348 | #
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349 | # The reloadproc functions sends a signal to a daemon telling it to
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350 | # reload it's configuration file. This is almost identical to the
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351 | # killproc function with the exception that it won't try to kill it with
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352 | # a -KILL signal (aka -9)
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353 | #
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354 |
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355 | reloadproc()
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356 | {
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357 |
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358 | #
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359 | # If no parameters are given to the print_status function, print usage
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360 | # information.
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361 | #
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362 |
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363 | if [ $# = 0 ]
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364 | then
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365 | echo "Usage: reloadproc {program} [signal]"
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366 | exit 1
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367 | fi
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368 |
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369 | #
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370 | # Find the basename of the first parameter (the daemon's name without
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371 | # the path that was provided so /usr/sbin/syslogd becomes plain 'syslogd'
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372 | # after basename ran)
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373 | #
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374 |
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375 | base=$(/usr/bin/basename $1)
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376 |
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377 | #
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378 | # Check if we gave a signal to send to the process (like -HUP)
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379 | # to this function (the second parameter). If no second
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380 | # parameter was provided set the nolevel variable. Else set the
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381 | # killlevel variable to the value of $2 (the second parameter)
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382 | #
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383 |
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384 | if [ -n "$2" ]
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385 | then
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386 | killlevel=-$2
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387 | else
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388 | nolevel=1
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389 | fi
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390 |
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391 | #
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392 | # the pidlist variable will contains the output of the pidof command.
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393 | # pidof will try to find the PID's that belong to a certain string;
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394 | # $base in this case
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395 | #
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396 |
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397 | pidlist=$(/bin/pidof -o $$ -o $PPID -o %PPID -x $base)
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398 |
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399 | pid=""
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400 |
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401 | for apid in $pidlist
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402 | do
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403 | if [ -d /proc/$apid ]
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404 | then
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405 | pid="$pid $apid"
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406 | fi
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407 | done
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408 |
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409 | #
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410 | # If $pid contains something from the previous for loop it means one or
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411 | # more PID's were found that belongs to the processes to be reloaded
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412 | #
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413 |
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414 | if [ -n "$pid" ]
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415 | then
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416 |
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417 | #
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418 | # If nolevel was set we will use the default reload signal SIGHUP.
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419 | #
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420 |
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421 | if [ "$nolevel" = 1 ]
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422 | then
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423 | /bin/kill -SIGHUP $pid
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424 | evaluate_retval
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425 | else
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426 |
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427 | #
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428 | # Else we will use the provided signal
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429 | #
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430 |
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431 | /bin/kill $killlevel $pid
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432 | evaluate_retval
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433 | fi
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434 | else
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435 |
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436 | #
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437 | # If $pid is empty no PID's have been found that belong to the process.
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438 | # Print [ ATTN ]
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439 | #
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440 |
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441 | $SET_WCOL
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442 | echo -n "Not running"
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443 | print_status warning
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444 | fi
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445 | }
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446 |
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447 | #
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448 | # The statusproc function will try to find out if a process is running
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449 | # or not
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450 | #
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451 |
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452 | statusproc()
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453 | {
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454 |
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455 | #
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456 | # If no parameters are given to the print_status function, print usage
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457 | # information.
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458 | #
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459 |
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460 | if [ $# = 0 ]
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461 | then
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462 | echo "Usage: status {program}"
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463 | return 1
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464 | fi
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465 |
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466 | #
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467 | # $pid will contain a list of PID's that belong to a process
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468 | #
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469 |
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470 | pid=$(/bin/pidof -o $$ -o $PPID -o %PPID -x $1)
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471 | if [ -n "$pid" ]
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472 | then
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473 |
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474 | #
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475 | # If $pid contains something, the process is running, print the contents
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476 | # of the $pid variable
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477 | #
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478 |
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479 | echo "$1 running with Process ID $pid"
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480 | return 0
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481 | fi
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482 |
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483 | #
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484 | # If $pid doesn't contain it check if a PID file exists and inform the
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485 | # user about this stale file.
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486 | #
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487 |
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488 | if [ -f /var/run/$1.pid ]
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489 | then
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490 | pid=$(/usr/bin/head -1 /var/run/$1.pid)
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491 | if [ -n "$pid" ]
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492 | then
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493 | echo "$1 not running but /var/run/$1.pid exists"
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494 | return 1
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495 | fi
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496 | else
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497 | echo "$1 is not running"
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498 | fi
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499 |
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500 | }
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501 |
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502 | # End /etc/init.d/functions
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503 | <userinput>EOF</userinput></screen></para>
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504 |
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505 | </sect1>
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506 |
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