Shell character interception

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.

echo ${var#*//}

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

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

echo ${var##*/}

##*/indicates that the last (rightmost) one/number and all characters to the left are deleted from the left.
That is, delete http://www.aaa.com/

The result is 123.htm.

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

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

echo ${var/*}

%%/* indicates that the last (leftmost) one/number and right character are deleted from the right.
The result is: http:

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

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.

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

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.

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)

[Email protected]:~$var=http://www.aaa.com/123.htm[Email protected]:~$ Echovarvar[email protected]:~$ echo $varhttp://www.aaa.com/123.htm[Email protected]:~$ Echo ${var#*//}www.aaa.com/123. Htm[email protected]:~$ Echo ${var#*/}/www.aaa.com/123. Htm[email protected]:~$ Echo ${var##*/}123. Htm[email protected]:~$ Echo ${var%*/}http://www.aaa.com/123.htm[Email protected]:~$ Echo ${var%/}http://www.aaa.com/123.htm[Email protected]:~$ Echo ${var%/*}http://www.aaa.com[email protected]:~$ echo ${var%%/*}http:[email protected]:~$ echo ${var:1:1}t[email protected]:~$ echo ${var:3:5}p ://w[email protected]:~$ echo ${var::5}http:[email protected]:~$ echo ${var:5}//www.aaa.com/123.htm[email protected]: ~$ echo ${var:0-2:5}tm[email protected]:~$ echo ${var:0-6:5}23.ht[email protected]:~$ echo ${var:0-6}23.htm[email protected]:~$

Shell character interception