Tutorial by Examples: i

A minimal Dockerfile looks like this: FROM alpine CMD ["echo", "Hello StackOverflow!"] This will instruct Docker to build an image based on Alpine (FROM), a minimal distribution for containers, and to run a specific command (CMD) when executing the resulting image. Build an...
To copy files from the build context in a Docker image, use the COPY instruction: COPY localfile.txt containerfile.txt If the filename contains spaces, use the alternate syntax: COPY ["local file", "container file"] The COPY command supports wildcards. It can be used for ...
To declare exposed ports from a Dockerfile use the EXPOSE instruction: EXPOSE 8080 8082 Exposed ports setting can be overridden from the Docker commandline but it is a good practice to explicitly set them in the Dockerfile as it helps understand what an application does.
Group common operations Docker builds images as a collection of layers. Each layer can only add data, even if this data says that a file has been deleted. Every instruction creates a new layer. For example: RUN apt-get -qq update RUN apt-get -qq install some-package Has a couple of downsides: ...
_mycompletion() { local command_name="$1" # not used in this example local current_word="$2" local previous_word="$3" # not used in this example # COMPREPLY is an array which has to be filled with the possible completions # compgen is used to fi...
It is possible to save a Docker container's filesystem contents to a tarball archive file. This is useful in a pinch for moving container filesystems to different hosts, for example if a database container has important changes and it isn't otherwise possible to replicate those changes elsewhere. Pl...
Search engines won't index your products if you have a URL like the following: http://www.yourdomain.com/product.php?id=123 SEO friendly URL would look like http://www.yourdomain.com/123/product-name/. The following code helps achieve this without having to change product.php code. RewriteEng...
RewriteEngine on RewriteCond %{HTTP_REFERER} !^$ RewriteCond %{HTTP_REFERER} !^http://(www\.)?yourdomain.com/.*$ [NC] RewriteRule \.(gif|jpg|css)$ - [F] This blocks all the links to '.gif', '.jpg' and '.css' files which are not from the domain name http://www.yourdomain.com. Display alterna...
3.0 The most simple way is to use sorted(): let words = ["Hello", "Bonjour", "Salute", "Ahola"] let sortedWords = words.sorted() print(sortedWords) // ["Ahola", "Bonjour", "Hello", "Salute"] or sort() var mutable...
Let's swap the implementation of methodOne() and methodTwo() in our TestSwizzling class: class TestSwizzling : NSObject { dynamic func methodOne()->Int{ return 1 } } extension TestSwizzling { //In Objective-C you'd perform the swizzling in load(), //but t...
import fileinput replacements = {'Search1': 'Replace1', 'Search2': 'Replace2'} for line in fileinput.input('filename.txt', inplace=True): for search_for in replacements: replace_with = replacements[search_for] line = line.replace(search_for, replace_with...
The method compareTo should be used to compare BigDecimals: BigDecimal a = new BigDecimal(5); a.compareTo(new BigDecimal(0)); // a is greater, returns 1 a.compareTo(new BigDecimal(5)); // a is equal, returns 0 a.compareTo(new BigDecimal(10)); // a is less, returns -1 Commonly you shou...
A powerful alternative to virtualenv is Anaconda - a cross-platform, pip-like package manager bundled with features for quickly making and removing virtual environments. After installing Anaconda, here are some commands to get started: Create an environment conda create --name <envname> pyth...
let numbers = [3, 1, 4, 1, 5] // non-functional for (index, element) in numbers.enumerate() { print(index, element) } // functional numbers.enumerate().map { (index, element) in print((index, element)) }
Applying a function to a collection/stream and creating a new collection/stream is called a projection. /// Projection var newReleases = [ [ "id": 70111470, "title": "Die Hard", "boxart": "http://cdn-0.nflximg.com/images...
Create a stream by selecting the elements from a stream that pass a certain condition is called filtering var newReleases = [ [ "id": 70111470, "title": "Die Hard", "boxart": "http://cdn-0.nflximg.com/images/2891/DieHard.j...
A HAVING clause filters the results of a GROUP BY expression. Note: The following examples are using the Library example database. Examples: Return all authors that wrote more than one book (live example). SELECT a.Id, a.Name, COUNT(*) BooksWritten FROM BooksAuthors ba INNER JOIN Aut...
We can use 1,2,3.. to determine the type of order: SELECT * FROM DEPT ORDER BY CASE DEPARTMENT WHEN 'MARKETING' THEN 1 WHEN 'SALES' THEN 2 WHEN 'RESEARCH' THEN 3 WHEN 'INNOVATION' THEN 4 ELSE 5 END, CITY IDREGIONCITYDEPARTMENTEMPLOYEES_N...
PostgreSQL and SQLite To create a temporary table local to the session: CREATE TEMP TABLE MyTable(...); SQL Server To create a temporary table local to the session: CREATE TABLE #TempPhysical(...); To create a temporary table visible to everyone: CREATE TABLE ##TempPhysicalVisibleToEveryo...
When results need to have some logic applied 'on the fly' one can use CASE statement to implement it. SELECT CASE WHEN Col1 < 50 THEN 'under' ELSE 'over' END threshold FROM TableName also can be chained SELECT CASE WHEN Col1 < 50 THEN 'under' WHEN Col1 > 50 AND Col1 ...

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