Linux shell字符串截取、替换、删除以及trim

1. 字符串截取

   • 从左向右截取第一个//后的字符串

     word=abcd-//master-01://httpab
     echo ${word#*//} 
     # 输出:master-01://httpab
     

   • 从左向右截取最后一个//后的字符串

     word=abcd-//master-01://httpab
     echo ${word##*//} 
     # 输出:httpab
     

   • 从右向左截取第一个//后的字符串

     word=abcd-//master-01://httpab
     echo ${word%//*} 
     # 输出:abcd-//master-01:
     

   • 从右向左截取最一个//后的字符串

     word=abcd-//master-01://httpab
     echo ${word%%//*} 
     # 输出:abcd-
     

   • 截取位置0后3个字符

     word=abcd-//master-01://httpab
     echo ${word:0:3} 
     # 输出:abc
     

   • 从位置1截取到末尾

     word=abcd-//master-01://httpab
     echo ${word:1} 
     # 输出:bcd-//master-01://httpab
     

   • 从位置-1截取到末尾，就是截取最后一个

     word=abcd-//master-01://httpab
     echo ${word:(-1)} 
     # 输出:b
     

2. 字符串替换

   • 从左到右，匹配第一个，替换//为cd

     word=abcd-//master-01://httpab
     echo ${word/\/\//cd} 
     # 输出:abcd-cdmaster-01://httpab
     

   • 将所有匹配的//替换为cd

     word=abcd-//master-01://httpab
     echo ${word//\/\//cd} 
     # 输出:abcd-cdmaster-01:cdhttpab
     

   • 前缀匹配，只匹配从位置0开始的字符

     word=abcd-//master-01://httpab
     echo ${word/#ab/cd} 
     # -不是前缀，会匹配失败
     echo ${word/#-/cd}
     # 输出:abcd-cdmaster-01://httpab
     # 输出:abcd-//master-01://httpab
     

   • 后缀匹配，只匹配结尾字符

     word=abcd-//master-01://httpab
     echo ${word/%http*/xy} 
     # 输出:abcd-//master-01://xy
     echo ${word/%ab/xy}
     # 输出:abcd-//master-01://httpxy
     echo ${word/%ab*/xy}
     # 出现*，会从起始匹配
     # 输出:xy
     

3. 字符串删除

   • 利用字符截取和替换，以及拼接可以实现删除字符的效果

   • 删除前3个字符

     word=abcd-//master-01://httpab
     echo ${word#*${word:0:3}} 
     # 输出:d-//master-01://httpab
     

   • 删除后3个字符

     word=abcd-//master-01://httpab
     echo ${word%*${word:(-3)}} 
     # 输出:abcd-//master-01://htt
     

   • 删除第一个ab

     word=abcd-//master-01://httpab
     echo ${word/ab/} 
     # 输出:cd-//master-01://httpab
     

   • 删除所有ab

     word=abcd-//master-01://httpab
     echo ${word//ab/} 
     # 输出:cd-//master-01://http
     

   • 删除最后一个ab

     word=abcd-//master-01://httpabcd
     echo ${word%ab*}${word##*ab}
     # 输出:abcd-//master-01://httpcd
     

4. 字符串trim

   • 利用xargs可以实现trim

     word="   hello  wolrd  "
     word=`echo $word | xargs`
     echo $word
     # 输出:hello  wolrd
     

参考博客：https://www.cnblogs.com/gaochsh/p/6901809.html