Summary of 8 methods of string interception in shell scripts

String interception of Linux is useful. There are eight ways.

Suppose there is a variable var=http://www.aaa.com/123.htm.

1. # Intercept, delete the left character, leave the right character.

The code looks like this: Echo ${var#*//}

where Var is the variable name and the # is an operator, *//means that deleting the first//number from the left and all the characters on the left is deleted HTTP//The result is: www.aaa.com/123.htm

2. # # Intercept, delete the left character and leave the right character.

The code looks like this: Echo ${var##*/}

##*/means delete the last (rightmost) one/number and all characters on the left, starting from the left http://www.aaa.com/

The result is 123.htm.

3.% Intercept, delete right character, leave left character

The code looks like this: Echo ${var%/*}

%/* indicates that the first/second and right characters are deleted from the right.

The result is: http://www.aaa.com

4. The percent number intercept, delete the right character, leave the left character

The code looks like this: Echo ${var%%/*}

%%/* means starting from the right, deleting the last (leftmost) one/number and the right character result is: http:

5. Start with the first few characters on the left and the number of characters

The code looks like this: Echo ${var:0:5}

0 represents the first character on the left and 5 indicates the total number of characters. The result is: http:

6. Start with the first few characters on the left and continue to the end.

The code looks like this: Echo ${var:7}

7 means that the 8th character on the left begins, until the end. The result is: www.aaa.com/123.htm

7. Start with the first few characters on the right and the number of characters

The code looks like this: Echo ${var:0-7:3}

0-7 means that the seventh character starts at the right, and 3 indicates the number of characters. The result is: 123

8. Start with the first few characters on the right and continue to the end.

The code looks like this: Echo ${var:0-7}

The expression starts at the seventh character on the right and continues to the end. Result is: 123.htm

Note: (The first character on the left is denoted by 0, and the first character on the right is denoted by 0-1)

Summary of 8 methods of string interception in shell scripts