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Why strings are enclosed within the single or double quotes?
Double quotes mean a string in many other languages. When you learn a new language like Java or C, double quotes are always used. In Ruby, PHP and Perl, single-quoted strings imply no backslash escapes while double quotes support them.
Should I use single or double quotes JavaScript?
In JavaScript, single (‘ ‘) and double (“ ”) quotes are frequently used for creating a string literal. Generally, there is no difference between using double or single quotes, as both of them represent a string in the end.
How to use variables in single quoted strings?
Variables are expanded in double quoted strings, but not in single quoted strings: If you can simply switch quotes, do so. If you prefer sticking with single quotes to avoid the additional escaping, you can instead mix and match quotes in the same argument: $ echo ‘single quoted.
How to build a string containing a variable value surrounded?
1. The single-quotes are obligatory, and can’t be replaced by, say, double-quotes 2. my_file.sql is a variable known only at run-time. So what I need is a way to have bash build a string that on one hand contains a variable value, while on the other hand that value should be surrounded by single quotes.
How to use double quotes in a variable?
You could used double quotes around your command, and then use whatever single and double quotes you need inside provided you escape double ones. use printf to replace the variable token with the expanded variable. Variables can contain single quotes.
How is a word preserved inside a single quote?
Inside single quotes everything is preserved literally, without exception. That means you have to close the quotes, insert something, and then re-enter again. Word concatenation is simply done by juxtaposition. As you can verify, each of the above lines is a single word to the shell.