shell 字符串详细使用

#!/bin/bashstring="abcABC123EFGH"#字符串长度echo ${#string}  # 输出13echo `expr length $string`  # 输出13#索引#用法：expr index $string $substringecho `expr index $string "ABC"`  # 输出4#提取子串#用法：${string:postion}echo ${string:3}  # 输出ABC123EFGH#提取指定长度子串#用法：${string:3:3}echo ${string:3:3}  # 输出ABC#从末尾提取子串#用法：#${string: -length}注意有空格 #${string:(-length)}echo ${string:(-3)}  #输出FGH#子串剔除#从左边开始截吊第一个匹配的$substring#用法：${string#*substring}echo ${string#*abc}  # 输出ABC123EFGHsubstr="abc"echo ${string#*$substr}  # 输出ABC123EFGH#从左边开始截吊最后一个匹配的$substringecho ${string##*abc}  # 输出ABC123EFGH#从右边开始截吊第一个匹配的$substring#用法:${string%substring*}echo ${string%GH*} #输出abcABC123EF#从右边开始截吊最后一个匹配的$substringecho ${string%%GH*} #输出abcABC123EF#子串替换#用$replacement来替换第一个匹配的$substring#用法：${string/substring/replacement}echo ${string/ABC/XYZ} # 输出abcXYZ123EFGH#用$replacement来替换全部匹配的$substring#用法：${string//substring/replacement}echo ${string//ABC/XYZ} #输出abcXYZ123EFGH#如果$substring匹配$string的开头部分，那么就用$replacement来替换#用法：${string/#substring/replacement}echo ${string/#abc/xyz} #输出xyzABC123EFGH#如果$substring匹配$string的结尾部分，那么就用$replacement来替换#用法：${string/%substring/replacement}echo ${string/%GH/xyz}  #输出abcABC123EFxyz