shell create pid file , avoid script running multiple times

mutex.sh

#!/bin/sh

## create pid file , avoid script running multiple times
### every script gen a unique UUID
UUID=ACD35429D76148978480EA945653D112
pid_file=/tmp/${UUID}.pid

if [[ -f $pid_file ]]; then
  lpid=$(head -1 $pid_file)
  if [[ ! -z $lpid ]]; then
    if [[ $(ps -ef | grep 'sh ' | awk '{print $2}' | egrep "^${lpid}$") ]]; then
      echo "same script has running ... pid is $lpid , exit ..."
      exit 0
    fi
  fi
fi
echo $$ > $pid_file


## content



sleep 10





## last remove pid file
rm -f $pid_file
exit 0