shell 正则匹配

[ucd@ucd1 svnVersion]$ cat a4.sh 
java_version='1.8.2';
if [[ $java_version =~ ^1.8 ]]
  then
   echo 'aaaaaaaaaa'
else
   echo 'bbbbbbbbb'
fi
[ucd@ucd1 svnVersion]$ 
[ucd@ucd1 svnVersion]$ sh ./a4.sh 
aaaaaaaaaa

[ucd@ucd1 svnVersion]$ cat a4.sh 
java_version='3.1.8.2';
if [[ $java_version =~ ^1.8 ]]
  then
   echo 'aaaaaaaaaa'
else
   echo 'bbbbbbbbb'
fi
[ucd@ucd1 svnVersion]$ sh ./a4.sh 
bbbbbbbbb


[ucd@ucd1 svnVersion]$ cat a4.sh 
java_version='3.1.8.2';
if [[ $java_version =~ 1.8 ]]
  then
   echo 'aaaaaaaaaa'
else
   echo 'bbbbbbbbb'
fi