A Linux string truncation is useful. There are eight methods.
Suppose there is variable var=http://www.linuxidc.com/123.htm
1# interception, delete the left character, keep the right character.
echo $ {var # * //
Where var is the variable name, the # sign is the operator, *// means to delete the first // sign and all the characters on the left from the left
i.e. remove http://
The result is: www.linuxidc.com/123.htm
.
2 ## interception, delete the left character, keep the right character.
echo $ {var ## * /
##*/ means to delete the last (rightmost) / sign and all characters on the left from the left
i.e. remove http://www.linuxidc.com/
The result is 123.htm
3 % sign interception, delete the right character, keep the left character
echo $ {var% / *
%/* means start from the right, delete the first / sign and the characters to the right
The result is: http://www.linuxidc.com
4 %% interception, delete the characters on the right, keep the characters on the left
echo $ {var %% / *
%%/* means start from the right, delete the last (leftmost) / sign and the characters to the right
The result is: http:
5 Starting from the first character from the left, and the number of characters
echo $ {var: 0: 5
Where 0 indicates the start of 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 from the left and continue to the end.
echo $ {var: 7
The 7 represents the beginning of the 8th character from the left and continues until the end.
The result is: www.linuxidc.com/123.htm
7Starting from the first character on the right, and the number of characters
echo $ {var: 0-7: 3
Among them, 0-7 means starting from the seventh character from the right, and 3 means the number of characters.
The result is: 123
8 Start with the first few characters from the right and continue to the end.
echo $ {var: 0-7
Indicates from the seventh character from the right to the end.
The result is: 123.htm
。
。
Note: (the first character on the left is represented by 0, and the first character on the right is represented by 0-1)
Two splicing method of strings in Linux Shell script
If you want to add a character after the variable, you can use the following method:
$value1=home
$value2=${value1}"="
echo $value2Add
{} to the string variable to be added, and you need to put $ outside .
The result of this output is: home=, which means that 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/
http://www.linuxidc.com/Linux/2015-03/115198.htm