参考书目：鸟哥的LINUX私房菜基础学习篇（第三版）
Linux Shell Scripting Cookbook
本节主要内容
- 基础正则表达式
1. 基础正则表达式
(1)^行开始符
^匹配一行的开始，例如’^Spark’ 匹配所有Spark开始的行
//grep -n表示查找到的结果显示行号
root@sparkslave02:~/ShellLearning# grep -n '^Spark' /hadoopLearning/spark-1.5.0-bin-hadoop2.4/README.md
3:Spark is a fast and general cluster computing system for Big Data. It provides
22:Spark is built using [Apache Maven](http://maven.apache.org/).
53:Spark also comes with several sample programs in the `examples` directory.
83:Spark uses the Hadoop core library to talk to HDFS and other Hadoop-supported
(2)$行结束符
匹配一行的结束，例如′Spark’ 匹配所有以Spark结束的行
root@sparkslave02:~/ShellLearning# grep -n 'Spark$' /hadoopLearning/spark-1.5.0-bin-hadoop2.4/README.md
1:# Apache Spark
20:## Building Spark
(3).匹配任意一个字符
例如 Spa.k可以匹配Spark、Spaak等
root@sparkslave02:~/ShellLearning# grep -n 'Spa.k' /hadoopLearning/spark-1.5.0-bin-hadoop2.4/README.md
1:# Apache Spark
3:Spark is a fast and general cluster computing system for Big Data. It provides
6:rich set of higher-level tools including Spark SQL for SQL and
//其它省略
上面没有匹配小写spark，要匹配可以采用
//-i选项表示忽略大小写
root@sparkslave02:~/ShellLearning# grep -in 'Spa.k' /hadoopLearning/spark-1.5.0-bin-hadoop2.4/README.md 
(4)[]匹配其中一个
[Ss]park只匹配Spark和spark
root@sparkslave02:~/ShellLearning# grep -n '[Ss]park' /hadoopLearning/spark-1.5.0-bin-hadoop2.4/README.md
1:# Apache Spark
3:Spark is a fast and general cluster computing system for Big Data. It provides
6:rich set of higher-level tools including Spark SQL for SQL and DataFrames,
8:and Spark Streaming for stream processing.
10:<http://spark.apache.org/>
//其它省略
(5) [^]不匹配[]中的任何一个字符
例如 ‘[^T]he’ ，不匹配The，但可匹配 the、che等
root@sparkslave02:~/ShellLearning# grep -n '[^T]he' /hadoopLearning/spark-1.5.0-bin-hadoop2.4/README.md
(6) [-]匹配固定范围的字符
例如[a-h]he，只匹配ahe、bhe、che…hhe，不匹配ihe、the等
root@sparkslave02:~/ShellLearning# grep -n '[a-h]he' /hadoopLearning/spark-1.5.0-bin-hadoop2.4/README.md
1:# Apache Spark
6:rich set of higher-level tools including Spark SQL for SQL and DataFrames,
10:<http://spark.apache.org/>
16:guide, on the [project web page](http://spark.apache.org/documentation.html)
(7)? 匹配0次或1次
例如t?he只匹配he和the，不匹配tthe
//?属于特殊符号，需要\进行转义
root@sparkslave02:~/ShellLearning# grep -n 't\?he' /hadoopLearning/spark-1.5.0-bin-hadoop2.4/README.md
1:# Apache Spark
6:rich set of higher-level tools including Spark SQL for SQL and DataFrames,
10:<http://spark.apache.org/>
15:You can find the latest Spark documentation, including a programming
16:guide, on the [project web page](http://spark.apache.org/documentation.html)
//其它省略
(8)+ 至少匹配一次
‘S+park’可以匹配Spark、SSpark、SSSpark等
root@sparkslave02:~/ShellLearning# grep -n 'S\+park' /hadoopLearning/spark-1.5.0-bin-hadoop2.4/README.md
(9) * 匹配零次或多少
‘S*park’可匹配park、Spark、SSpark、SSSpark等
root@sparkslave02:~/ShellLearning# grep -n 'S*park' /hadoopLearning/spark-1.5.0-bin-hadoop2.4/README.md
1:# Apache Spark
3:Spark is a fast and general cluster computing system for Big Data. It provides
6:rich set of higher-level tools including Spark SQL for SQL and DataFrames,
8:and Spark Streaming for stream processing.
10:<http://spark.apache.org/>
15:You can find the latest Spark documentation, including a programming
//其它省略
(10) {n}，匹配n次
例如[a-z]{3}，匹配任意3个小写字母，等同于[a-z][a-z][a-z]
root@sparkslave02:~/ShellLearning# grep -n '[a-z]\{3\}' /hadoopLearning/spark-1.5.0-bin-hadoop2.4/README.md
1:# Apache Spark
3:Spark is a fast and general cluster computing system for Big Data. It provides
(11) 其它限定次数匹配
{n, }至少匹配n次
{n, m}至少匹配n次，最多匹配m次
(13) 转义字符\
Ubuntu Linux ?,+,(,), {,}是特殊字符，在使用正则表达式时，如果不加转义符，会匹配将其视为一般字符，如果要设置为正则表达式式符，需要使用\进行转义，前面的例子已经给出示例。
(14) ()匹配一组字符
例如Sp(ar)\?k 匹配Spark和Spk，
root@sparkslave02:~/ShellLearning# echo "Spark Spk Spak" | grep -n 'Sp\(ar\)\?k'
1:Spark Spk Spak
(15) URL匹配实战
root@sparkslave02:~/ShellLearning/Chapter15# grep -n '[A-Za-z]*://[A-Za-z]*\.\(\([A-Za-z]*\)\.\?\)*' /hadoopLearning/spark-1.5.0-bin-hadoop2.4/README.md
上面整个例子可以分下列步骤完成：
(1)匹配http://
root@sparkslave02:~/ShellLearning/Chapter15# grep -n '[A-Za-z]*://' /hadoopLearning/spark-1.5.0-bin-hadoop2.4/README.md 
(2)匹配域名
root@sparkslave02:~/ShellLearning/Chapter15# grep -n '[A-Za-z]*://[A-Za-z]*\.[A-Za-z]*' /hadoopLearning/spark-1.5.0-bin-hadoop2.4/README.md
(3)处理重复部分
root@sparkslave02:~/ShellLearning/Chapter15# grep -n '[A-Za-z]*://[A-Za-z]*\.\(\([A-Za-z]*\)\.\?\)*' /hadoopLearning/spark-1.5.0-bin-hadoop2.4/README.md 
