65 lines
1.3 KiB
Bash
Executable File
65 lines
1.3 KiB
Bash
Executable File
#!/bin/bash
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lockfile="/.nslock"
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SUCCESS=0
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FAIL=1
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otherpid=
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startparent()
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{
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rm -f $lockfile
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echo $$ >| ${lockfile}parent
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while [ 1 ]
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do
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otherpid="$(cat ${lockfile}child 2> /dev/null)"
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if [ -n "$otherpid" -a -d /proc/$otherpid ]
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then
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return
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fi
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done
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}
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startchild()
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{
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rm -f $lockfile
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echo $$ >| ${lockfile}child
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while [ 1 ]
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do
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otherpid="$(cat ${lockfile}parent 2> /dev/null)"
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if [ -n "$otherpid" -a -d /proc/$otherpid ]
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then
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return
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fi
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done
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}
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iamgoingahead()
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{
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while [ 1 ]
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do
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if [ ! -d /proc/$otherpid ]
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then
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return $FAIL
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fi
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str=`cat $lockfile 2> /dev/null`
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pid=$(echo $str | awk '{print $1}')
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error=$(echo $str | awk '{print $2}')
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if [ "$pid" == "$$" ]
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then
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return $error
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fi
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sleep 1
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done
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}
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goahead()
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{
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set -x
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ret=$SUCCESS
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if [ -n "$1" ]
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then
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ret=$1
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fi
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echo "$otherpid $ret" >| $lockfile
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set +x
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}
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