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正则表达式（Regular Expression ,RE）是处理字符串的方法，它是以行为单位来进行字符串的处理行为，
通过一些特殊符号的辅助，可以让用户轻易达到查找，删除，替换某特定字符串的处理程序。
#!/bin/bash if [ $# == 0 ];then echo "Please input parameters:" echo "dmesg OR txt" fi if [ "$1" == "dmesg" ];then dmesg | grep ‘eth‘ echo "******************" dmesg | grep -A1 -B2 ‘eth‘ echo "******************" dmesg | grep -A1 -B2 -n --color=auto ‘eth‘ fi if [ "$1" == "txt" ];then echo "**********************lines with ‘the‘***********************" grep -n --color=auto ‘the‘ ./material/regular_express.txt echo "**********************lines without ‘the‘********************" grep -v -n --color=auto ‘the‘ ./material/regular_express.txt echo "**********************lines with ‘the‘(no matter lower or bigger)********************" grep -i -n --color=auto ‘the‘ ./material/regular_express.txt echo "**********************lines with ‘t[ae]st‘********************" grep -n --color=auto ‘t[ae]st‘ ./material/regular_express.txt echo "**********************lines with ‘oo‘********************" grep -n --color=auto ‘oo‘ ./material/regular_express.txt echo "**********************lines without ‘oo‘starting with g ********************" grep -n --color=auto ‘[^g]oo‘ ./material/regular_express.txt echo "**********************lines without ‘oo‘starting with a-z ********************" grep -n --color=auto ‘[^a-z]oo‘ ./material/regular_express.txt echo "**********************lines without ‘oo‘starting with lower ********************" grep -n --color=auto ‘[^[:lower:]]oo‘ ./material/regular_express.txt echo "**********************lines without digit ********************" grep -n --color=auto ‘[^[:digit:]]‘ ./material/regular_express.txt echo "**********************lines starting with ‘the‘ ********************" grep -n --color=auto ‘^the‘ ./material/regular_express.txt echo "**********************lines starting with lower ********************" grep -n --color=auto ‘^[a-z]‘ ./material/regular_express.txt echo "**********************lines not starting with character ********************" grep -n --color=auto ‘^[^a-zA-Z]‘ ./material/regular_express.txt echo "**********************lines ending with ‘.‘ ********************" grep -n --color=auto ‘\.$‘ ./material/regular_express.txt echo "**********************display lines which are not empty and not begining with # ********************" grep -v -n --color=auto ‘^$‘ ./material/regular_express.txt | grep -v -n ‘^#‘ echo "**********************lines with g..d ********************" grep -n --color=auto ‘g..d‘ ./material/regular_express.txt echo "**********************lines with no less than 2 oo (* means 0 or more) ********************" grep -n --color=auto ‘ooo*‘ ./material/regular_express.txt echo "**********************lines with string which begins with g and ends with g********************" grep -n --color=auto ‘g.*g‘ ./material/regular_express.txt echo "**********************lines with 2-5 o in go..g ********************" grep -n --color=auto ‘go\{2,5\}g‘ ./material/regular_express.txt echo "**********************lines with 2 o in go..g ********************" grep -n --color=auto ‘go\{2\}g‘ ./material/regular_express.txt echo "**********************lines with 2 or more o in go..g ********************" grep -n --color=auto ‘go\{2,\}g‘ ./material/regular_express.txt fi
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原文地址：http://www.cnblogs.com/wuqi/p/4709555.html
