【shell脚本】匹配文件中特定的段落

自己用shell脚本写了一个匹配文件中特定段落的小程序，现将思路和代码分享如下：

实现思路：

1. 文件中特定的段落的开始和结束位置必须有相应的标记；
2. 首先使用grep找到开始标记和结束标记所在行的行号；
3. 计算结束和开始标记之间有多少行；
4. 使用grep -A获取开始和结束标记之间的段落；

代码如下：

#!/bin/bash
# getlog.sh

#######################################################
# usage:         sh getlog.sh <filename> [outfilename]
# version:        1.0 
# author:        cnpirate
# release date:    2012-09-26
# contact:        zhaixing@qq.com
#######################################################

if [ "$1" == "--help" ]; then
    echo "usage: sh getlog.sh <filename> [outfilename]"
    exit 1
fi

if [ "$1" == "" ]; then
    echo "no file input!"
    echo "please use --help for usage."
    exit 2
fi

if [ ! -f "$1" ]; then
    echo "$1 is not a file!"
    echo "please use --help for usage."
    exit 3
fi

# the begining flag of the section
BeginFlag="<?xml"
# the ending flag of the section
EndFlag="</TestRun>"

declare -i Bnum
declare -i Enum
declare -i nums

# line number of the beginning flag
Bnum=$(grep -n "$BeginFlag" $1 | cut -d: -f1)
# line number of the ending flag
Enum=$(grep -n "$EndFlag" $1 | cut -d: -f1)
# lines between the begining and ending flag
nums=$(($Enum-$Bnum))

# output the result into stdout
if [ "$2" == "" ]; then
    grep -A $nums "$BeginFlag" $1
    exit 0
fi

# output the result into outfile
grep -A $nums "$BeginFlag" $1 > $2

参考文献：

[1].鸟哥的Linux私房菜-基础篇关于shell脚本的介绍，http://vbird.dic.ksu.edu.tw/linux_basic/0340bashshell-scripts.php