Linux shell string truncation and splicing, linuxshell

Linux shell string truncation and splicing, linuxshell

Linux string truncation is very useful. There are eight methods.

Assume there are variablesVar = http://www.linuxidc.com/123.htm 

1 # intercept, delete the characters on the left, and retain the characters on the right. 

Echo $ {var #*//}

Where var is the variable name and # is the operator,*//Indicates that the first // number and all characters on the left are deleted from the left.

DeleteHttp ://

The result is:Www.linuxidc.com/123.htm

.

2 ## intercept, delete the characters on the left, and retain the characters on the right.

Echo $ {var ##*/}

##*/Indicates that the last (rightmost) character and all characters on the left are deleted from the left.

DeleteHttp://www.linuxidc.com/

The result is 123.htm.

 

 

Intercept No. 3%, delete the right character, retain the Left character

Echo $ {var % /*}

%/* Indicates that the first/number and the character on the right are deleted from the right.

Result: http://www.linuxidc.com

 

 

Truncated at 4% %, delete the right character, retain the Left character

 

Echo $ {var % /*}

%/* Indicates that the last (leftmost) character and the character on the right are deleted from the right.

The result is: http:

 

5. Start from the number of characters on the left and the number of characters.

Echo $ {var: 0: 5}

 

0 indicates the first character on the left, and 5 indicates the total number of characters.

The result is: http:

6 starts from the number of characters on the left until the end.

Echo $ {var: 7}

7 indicates the start of 8th characters on the left until the end.

The result is:Www.linuxidc.com/123.htm

7Starting from the number of characters on the right and the number of characters

Echo $ {var: 0-7:3}

0-7 indicates the 7th character on the right and 3 indicates the number of characters.

Result: 123

8 starts from the number of characters on the right until the end.

Echo $ {var: 0-7}

Starts from the seventh character on the right and ends.

The result is 123.htm.

.

.

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

2. How to concatenate strings in Linux Shell scripts

To add a character to the variable, use the following method:


$ Value1 = home


$ Value2 =$ {value1} "="


Echo $ value2


Add {} to the string variable to be added, and put $ outside.


The output result is: home =, that is, the connection is successful.


Another example:


[Root @ localhost sh] # var1 =/etc/
[Root @ localhost sh] # var2 = yum. repos. d/
[Root @ localhost sh] # var3 =$ {var1 }$ {var2}
[Root @ localhost sh] # echo $ var3
/Etc/yum. repos. d/

 

Note: Reference connection: http://www.linuxidc.com/Linux/2015-03/115198.htm