HDFS DataNode 维护状态切换最佳实践

#!/bin/bash
?
cd /usr/local/service/hadoop/etc/hadoop
file=hdfshosts
if [ ! -f "$file" ];then
  echo "$file not exists"
  exit -1
fi
?
bak_file="$file.txt.bak"
if [ ! -f "$bak_file" ];then
  cp -f $file $file.txt.bak
fi 
?
output_file="$file.tmp"
## 生成json文件
echo '[' > "$output_file"
first_record=true
while IFS= read -r line
do
  if [ "$first_record" = false ]; then
    echo ',' >> "$output_file"
  fi
?
  echo "  {\\"hostName\\": \\"$line\\"}" >> "$output_file"
?
  first_record=false
done < "$file"
echo ']' >> "$output_file"
mv -f $output_file $file
chown hadoop:hadoop $file
chmod 755 $file
cat $file

#!/bin/bash
?
cd /usr/local/service/hadoop/etc/hadoop
file=hdfshosts
bak_file="$file.txt.bak"
cp -f $bak_file $file
chown hadoop:hadoop $file
chmod 755 $file
cat $file