Example of the hadoop configuration file automatically configured by Shell

#!/bin/bashread -p 'Please input the directory of hadoop , ex: /usr/hadoop :' hadoop_dirif [ -d $hadoop_dir ] ; then   echo 'Yes , this directory exist.'else    echo 'Error , this directory not exist.'   exit 1fiif [ -f $hadoop_dir/conf/core-site.xml ];then   echo "Now config the $hadoop_dir/conf/core-site.xml file."   read -p 'Please input the ip value of fs.default.name , i.e. hdfs://ip:port :' ip   i=1   while [ -z $ip ]   do      read -p 'Please input the ip value of fs.default.name , i.e. hdfs://ip:port :' ip      let i++       echo $i      if [ $i -gt 2 ];then         echo 'You have input three time , done , exit.'         exit 1      fi   done   if [ $ip = '' ];then       echo 'The value of ip can not null , exit.'      exit 1   fi    read -p "Please input the port value of fs.default.name , i.e. hafs://$ip:port :" port   if [ $port = '' ];then       echo 'The value of port can not null , exit.'      exit 1   fi   read -p 'Please input the dir value of hadoop.tmp.dir :' hadoop_tmp_dir   if [ $hadoop_tmp_dir = '' ];then      echo 'The value of hadoop.tmp.dir can not null , exit.'      exit 1   else      if [ ! -d $hadoop_tmp_dir ];then         echo 'The directory you have input is not exist , we will make it.'         mkdir -p $hadoop_tmp_dir      fi   fi   tmp_dir=$(echo $hadoop_tmp_dir|sed 's:/:\\/:g')         sed -i "s/ip/$ip/g" $hadoop_dir/conf/core-site.xml   sed -i "s/port/$port/g" $hadoop_dir/conf/core-site.xml    sed -i "s/tmp_dir/$tmp_dir/g" $hadoop_dir/conf/core-site.xmlelse    echo "The file $hadoop_dir/core-site.xml doen't exist."   exit 1ficat $hadoop_dir/conf/core-site.xmlecho 'Config the core-site.xml success !'echo 

Key Analysis:

1. tmp_dir = $ (echo $ hadoop_tmp_dir | SED's:/: \/: G ')

The $ hadoop_tmp_dir we entered is similar to:/usr/hadoop/tmp. If it is written directly in sed: sed-I "s/tmp_dir/$ hadoop_tmp_dir/g" $ hadoop_dir/CONF/core-site.xml, which causes an error. Because it will be parsed into: sed-I "s/tmp_dir/usr/hadoop/tmp/g" $ hadoop_dir/CONF/core-site.xml, apparently not satisfied, the solution is to convert the/usr/hadoop/tmp input to \/usr \/hadoop \/tmp, that is, add escape characters. Sed's:/: \/: G'. Then, use $ () to assign the value to the variable.

2. Sed-I "s/IP/$ IP/g" $ hadoop_dir/CONF/core-site.xml

Here is the replacement of strings in the file. The example file is:

root@ubuntu:/home/houqd/hadoop/conf# cat -n core-site.xml      1<?xml version="1.0"?>     2<?xml-stylesheet type="text/xsl" href="configuration.xsl"?>     3     4<!-- Put site-specific property overrides in this file. -->     5     6<configuration>     7<property>     8<name>fs.default.name</name>     9<value>hdfs://ip:port</value>    10</property>    11<property>    12<name>hadoop.tmp.dir</name>    13<value>tmp_dir</value>    14</property>    15</configuration>

3. Pay attention to other syntaxes: If []; then else fi while [] Do... done I = 0 let I ++