The logic is quite simple as such. So we look at bash source code (4.4) itself subst.c:9273 case ‘`’: /* Backquoted command substitution. */ { t_index = sindex++; temp = string_extract(string, &sindex, “`”, SX_REQMATCH); /* The test of sindex against t_index is to allow bare instances of ` to pass through, for backwards compatibility. */ … Read more
system(): runs command and returns command’s exit status backticks: runs command and returns the command’s output pipes : runs command and allows you to use them as an handle Also backticks redirects the executed program’s STDOUT to a variable, and system sends it to your main program’s STDOUT.
It’s because is is a reserved keyword in Kotlin. Since Kotlin is supposed to be interoperable with Java and is is a valid method (identifier) name in Java, the backticks are used to escape the method so that it can be used as a method without confusing it as a keyword. Without it it will … Read more
In MySQL, backticks quote names, while single quotes create strings. If you have a column called select, MySQL would throw an syntax error when using this name without backticks — like in SELECT select FROM foo — as it would interpret it as keyword which may not occur there. This IF function can be used … Read more
output = os.popen(‘cat /tmp/baz’).read()
A pair of backticks is a way to refer to names or combinations of symbols that are otherwise reserved or illegal. Reserved are words like if are part of the language, while illegal includes non-syntactic combinations like c a t. These two categories, reserved and illegal, are referred to in R documentation as non-syntactic names. … Read more
You can get a similar functionality using cmd.exe scripts with the for /f command: for /f “usebackq tokens=*” %%a in (`echo Test`) do my_command %%a Yeah, it’s kinda non-obvious (to say the least), but it’s what’s there. See for /? for the gory details. Sidenote: I thought that to use “echo” inside the backticks in … Read more
The major one is the ability to nest them, commands within commands, without losing your sanity trying to figure out if some form of escaping will work on the backticks. An example, though somewhat contrived: deps=$(find /dir -name $(ls -1tr 201112[0-9][0-9]*.txt | tail -1l) -print) which will give you a list of all files in … Read more
Using backticks permits you to use alternative characters. In query writing it’s not such a problem, but if one assumes you can just use backticks, I would assume it lets you get away with ridiculous stuff like SELECT `id`, `my name`, `another field` , `field,with,comma` Which does of course generate badly named tables. If you’re … Read more
This is a feature called template literals. They were called “template strings” in prior editions of the ECMAScript 2015 specification. Template literals are supported by Firefox 34, Chrome 41, and Edge 12 and above, but not by Internet Explorer. Examples: http://tc39wiki.calculist.org/es6/template-strings/ Official specification: ECMAScript 2015 Language Specification, 12.2.9 Template Literal Lexical Components (a bit dry) Template … Read more