Linux字符串操作

Posted 2021-10-09 Just_Get

Linux字符串操作

描述

shell内置一系列的操作符合，可以对字符串进行操作；

常用操作

表达式	含义
${#string}	$string的长度
${string:position}	在string中从位置position开始提取子串
${string:position:length}	在string中从位置position开始提取长度为$length的子串
${string#substring}	从变量string的开头删除最短匹配substring的子串
${string##substring}	从变量string的开头删除最长匹配substring的子串
${string%substring}	从变量string的结尾删除最短匹配substring的子串
${string%%substring}	从变量string的结尾删除最长匹配substring的子串
${string/substring/replacement}	使用replacement来代替第一个匹配的substring
${string//substring/replacement}	使用replacement来代替所有匹配的substring
${string/#substring/replacement}	使用replacement来代替string前缀匹配的substring
${string/%substring/replacement}	使用replacement来代替string后缀匹配的substring

示例

• ${#string}

[root@OpenWrtEXT:test]#test_str='/tmp/test/test/myvar'
[root@OpenWrtEXT:test]#echo $test_str
/tmp/test/test/myvar
[root@OpenWrtEXT:test]#echo ${#test_str}
20
[root@OpenWrtEXT:test]#

• ${string:position}

[root@OpenWrtEXT:test]#echo $test_str
/tmp/test/test/myvar
[root@OpenWrtEXT:test]#echo ${test_str:4}
/test/test/myvar
[root@OpenWrtEXT:test]#echo ${test_str:6}
est/test/myvar
[root@OpenWrtEXT:test]#

• ${string:position:length}

[root@OpenWrtEXT:test]#echo $test_str
/tmp/test/test/myvar
[root@OpenWrtEXT:test]#echo ${test_str:6:9}
est/test/
[root@OpenWrtEXT:test]#echo ${test_str:3:5}
p/tes
[root@OpenWrtEXT:test]#

• ${string#substring}

[root@OpenWrtEXT:test]#echo $test_str
/tmp/test/test/myvar
[root@OpenWrtEXT:test]#echo ${test_str#*test}
/test/myvar
[root@OpenWrtEXT:test]#

• ${string##substring}

[root@OpenWrtEXT:test]#echo $test_str
/tmp/test/test/myvar
[root@OpenWrtEXT:test]#echo ${test_str##*test}
/myvar
[root@OpenWrtEXT:test]#

• ${string%substring}

[root@OpenWrtEXT:test]#echo $test_str
/tmp/test/test/myvar
[root@OpenWrtEXT:test]#echo ${test_str%test*}
/tmp/test/
[root@OpenWrtEXT:test]#

• ${string%%substring}

[root@OpenWrtEXT:test]#echo $test_str
/tmp/test/test/myvar
[root@OpenWrtEXT:test]#echo ${test_str%%test*}
/tmp/
[root@OpenWrtEXT:test]#

• ${string/substring/replacement}

[root@OpenWrtEXT:test]#echo $test_str
/tmp/test/test/myvar
[root@OpenWrtEXT:test]#echo ${test_str/test/abc}
/tmp/abc/test/myvar
[root@OpenWrtEXT:test]#

• ${string//substring/replacement}

[root@OpenWrtEXT:test]#echo $test_str
/tmp/test/test/myvar
[root@OpenWrtEXT:test]#echo ${test_str//test/abc}
/tmp/abc/abc/myvar
[root@OpenWrtEXT:test]#

• ${string/#substring/replacement}

[root@OpenWrtEXT:test]#test_str='www.baidu.com'
[root@OpenWrtEXT:test]#echo $test_str
www.baidu.com
[root@OpenWrtEXT:test]#echo ${test_str/#www/abc}
abc.baidu.com
[root@OpenWrtEXT:test]#

• ${string/%substring/replacement}

[root@OpenWrtEXT:test]#echo $test_str
www.baidu.com
[root@OpenWrtEXT:test]#echo ${test_str/%com/abc}
www.baidu.abc
[root@OpenWrtEXT:test]#