Tutorial by Examples: l

To join all of an array's elements into a string, you can use the join method: console.log(["Hello", " ", "world"].join("")); // "Hello world" console.log([1, 800, 555, 1234].join("-")); // "1-800-555-1234" As you can see in ...

SELECT 'Hello world!' FROM dual; In Oracle's flavor of SQL, "dual is just a convienence table". It was originally intended to double rows via a JOIN, but now contains one row with a DUMMY value of 'X'.

To see the log with changes inline, use the -p or --patch options. git log --patch Example (from Trello Scientist repository) ommit 8ea1452aca481a837d9504f1b2c77ad013367d25 Author: Raymond Chou <[email protected]> Date: Wed Mar 2 10:35:25 2016 -0800 fix readme error link diff ...

You can overload the function call operator (): Overloading must be done inside of a class/struct: //R -> Return type //Types -> any different type R operator()(Type name, Type2 name2, ...) { //Do something //return something } //Use it like this (R is return type, a and b a...

Sourcing a file is different from execution, in that all commands are evaluated within the context of the current bash session - this means that any variables, function, or aliases defined will persist throughout your session. Create the file you wish to source sourceme.sh #!/bin/bash export A=...

Bosun alerts are defined in the config file using a custom DSL. They use functions to evaluate time series data and will generate alerts when the warn or crit expressions are non-zero. Alerts use templates to include additional information in the notifications, which are usually an email message and...

An assertion is a statement used to assert that a fact must be true when that line of code is reached. Assertions are useful for ensuring that expected conditions are met. When the condition passed to an assertion is true, there is no action. The behavior on false conditions depends on compiler fl...

To find files/directories with a specific name, relative to pwd: $ find . -name "myFile.txt" ./myFile.txt To find files/directories with a specific extension, use a wildcard: $ find . -name "*.txt" ./myFile.txt ./myFile2.txt To find files/directories matching one of ma...

To find files, use the -type f flag $ find . -type f To find directories, use the -type d flag $ find . -type d To find block devices, use the -type b flag $ find /dev -type b To find symlinks, use the -type l flag $ find . -type l

Sometimes we will need to run commands against a lot of files. This can be done using xargs. find . -type d -print | xargs -r chmod 770 The above command will recursively find all directories (-type d) relative to . (which is your current working directory), and execute chmod 770 on them. The -...

lscount returns a time bucketed count of matching documents in the LogStash index, according to the specified filter. A trivial use of this would be to check how many documents in total have been received in the 5 minutes, and alert if it is below a certain threshold. A Bosun alert for this might ...

lsstat returns various summary stats per bucket for the specified field. The field must be numeric in elastic. rStat can be one of avg, min, max, sum, sum_of_squares, variance, std_deviation. The rest of the fields behave the same as lscount, except that there is no division based on bucketDuratio...

The Promise.resolve static method can be used to wrap values into promises. let resolved = Promise.resolve(2); resolved.then(value => { // immediately invoked // value === 2 }); If value is already a promise, Promise.resolve simply recasts it. let one = new Promise(resolve => ...

#include <stdio.h> #define is_const_int(x) _Generic((&x), \ const int *: "a const int", \ int *: "a non-const int", \ default: "of other type") int main(void) { const int i = 1; int j = 1; double...

A lambda expression provides a concise way to create simple function objects. A lambda expression is a prvalue whose result object is called closure object, which behaves like a function object. The name 'lambda expression' originates from lambda calculus, which is a mathematical formalism invented...

If you specify the variable's name in the capture list, the lambda will capture it by value. This means that the generated closure type for the lambda stores a copy of the variable. This also requires that the variable's type be copy-constructible: int a = 0; [a]() { return a; // Ok, 'a' ...

On an ext filesystem, each file has a stored Access, Modification, and (Status) Change time associated with it - to view this information you can use stat myFile.txt; using flags within find, we can search for files that were modified within a certain time range. To find files that have been modifi...

Tuples group multiple values into a single compound value. The values within a tuple can be of any type and do not have to be of the same type as each other. Tuples are created by grouping any amount of values: let tuple = ("one", 2, "three") // Values are read using index n...

Tuples can be decomposed into individual variables with the following syntax: let myTuple = (name: "Some Name", age: 26) let (first, second) = myTuple print(first) // "Some Name" print(second) // 26 This syntax can be used regardless of if the tuple has unnamed properti...

Functions can return tuples: func tupleReturner() -> (Int, String) { return (3, "Hello") } let myTuple = tupleReturner() print(myTuple.0) // 3 print(myTuple.1) // "Hello" If you assign parameter names, they can be used from the return value: func tupleReturner(...