Original address: http://wenku.baidu.com/view/3e6a238271fe910ef12df806
"The distinction and usage of single and double quotes." Now the answer is summed up, written in this small essay. The fields inside the double quotes are interpreted by the
In ORACLE:Double quotation marks are used as follows:Object CreationWhen,Object Name and field nameDouble quotation marksOracle will be case sensitiveOtherwise, both of them are capitalized by default.
The single quotation marks indicate that the
There are three types of quotes in the shell: single quotes, double quotes, and anti-quotes. The single quotation mark ' character nonalphanumeric, enclosed by single quotes, appears as a normal character. When special characters are enclosed in
Fields in double quotation marks are interpreted by the compiler and then output as HTML code. The single quotes are output directly without explanation. For example: $ abcmynameistome; echo $ abc: mynameistomecho $ abc: $ abcecho $ abc: mynameistom
In Oracle:
Double quotation marks are used to indicate that when an object is created, the object name and field name are added with double quotation marks, indicating that Oracle will be case-sensitive. Otherwise, each else will be capitalized
One, single and double quotation marksFirst, both single and double quotes are meant to solve the problem of having spaces in the middle.Because the space in Linux as a very typical delimiter, such as String1=this is astring, so execution will be
"" Fields in double quotation marks are interpreted by the compiler and then output as HTML code.''Is output directly without being interpreted in single quotes.For example:
$ Abc = 'My name is tome '; echo $ ABC // The result is: My name is tomecho'
More and more open-source programs (PHP and Javascript) are using single quotes when processing strings. Why not use double quotation marks? What is the difference between the two? More and more open-source programs (PHP and Javascript) are using
Anti-QuoteThe anti-quote bit (') is located above the TAB key of the keyboard, to the left of the 1 key. Note the difference between the single quotation mark (') on the left side of the ENTER key.Plays the role of command substitution in Linux.
Original: http://blog.csdn.net/iamlaosong/article/details/54728393
Recently, to compile a shell script to process the data, you need to detect the existence of the data file, the file name contains the date, so you need to generate the date of the
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