Linux Shell Programming---Text slicing technology in the shell

Shell The technique of text slicing in

In the shell there is also a string slice this thing exists, has been used in Python slices, the following record the use of slices in the shell.

(1) , replacing some of the text in the variable contents

$var = "This was a line of text"

$ echo${var/line/replaced}

This is areplaced of text "

Line be replaced by replaced .

(2) , specifying the starting position and length of the string to generate the substring

The syntax is as follows:

${variable_name:start_position:length}

Print Section 5 after a character:

$string =abcdefghijklmnopqrstuvwxyz

$ echo${string:4}

Efghijklmnopqrstuvwxyz

from the first 5 characters start, print 8 characters:

$ echo${string:4:8}

Efghijkl

the index of the starting character is from 0 start counting. We can also count from the back forward and write the last character index as -1. However, if you use negative numbers as index values, you must enclose the negative numbers in parentheses. ( -1) is the index of the last character.

Echo${string: (-1)}

Z

$ echo${string: (-2): 2}

Yz

This article is from the "operation and maintenance of micro-letter" blog, please be sure to keep this source http://weixiaoxin.blog.51cto.com/13270051/1963717

Linux Shell Programming---Text slicing technology in the shell