how to extract a substring in bash

Question

I have the following string in bash with length > 4

str = "abcdefghijklmno" 

and I want to extract into str2 the 5 first charachter of str. So

str2="abcde" 

How to do it with bash?

Answer 1

Do use the expression

{string:position:length} 

So in this case:

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

See other usages:

$ 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 

Taken from:
- 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