如何提取在bash

Question

長度> 4

str = "abcdefghijklmno" 

一個子我有以下字符串中bash和欲提取到str2的str 5第一charachter。所以

str2="abcde" 

如何用bash做到這一點？

Answer 1

不要使用表達式

{string:position:length} 

因此，在這種情況下：

$ str="abcdefghijklm" 
$ echo "${str:0:5}" 
abcde 

見其他用途：

$ echo "${str:0}"  # default: start from the 0th position 
abcdefghijklm 
$ echo "${str:1:5}" # start from the 1th and get 5 characters 
bcdef 
$ echo "${str:10:1}" # start from 10th just one character 
k 
$ echo "${str:5}"  # start from 5th until the end 
fghijklm 

來自
- wooledge.org - How can I use parameter expansion? How can I get substrings? How can I get a file without its extension, or get just a file's extension?
- Shell Command Language - 2.6.2 Parameter Expansion