Author: andrea

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How to replace text everywhere in Git

There is a Git command, filter-branch, which works wonders for changing the history of a repository, but it’s difficult to use because it forces you to know how Git works under the hood. Instead there is this little free tool, BFG Repo-Cleaner, which is intuitive, fast and recommended.

Check that there are some occurrences of your string

The first thing to do is to check that the repository contains the string you want to replace with another string. This will help later to make sure you effectively replaced it.

Notice that, on the above git log line, the -G option allows to specify a regular expression, and the -i option allows to  ignore case.

Install BFG

BFG needs a JVM and you can install one with brew on a Mac.

Create search-replace.txt

BFG takes a file for specifying the text to search and replace. The accepted format is one replacement per line, like SEARCH==>REPLACE, with optional prefixes regex:, and glob:.

Use BFG

BFG acts on a bare repository which you can get by cloning with the --mirror option. Make sure the last commit doesn’t contains the text to be replaced, otherwise add a clean commit and push it before cloning.

Backup the old your-repository

You can recover this backup analogously to the section below.

Create a new your-repository

This step involves removing your remote old repository and creating a remote new one with the same name as before. Then you can push to it from your local repository using the --mirror option.

Check that your string was replaced by another string

If all is OK then you should see no results when searching again for your string but at least the same number of results you got when looking for it before if you now look for the replacement string.

 

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How to install WordPress with Docker on OS Sierra

With individual Docker commands

  1. Install Docker for Mac
  2. $ docker run –name mysql-latest -e MYSQL_ROOT_PASSWORD=my-secret-pw -d mysql:latest
  3. $ docker run –name wordpress -p 8000:80 –link mysql-latest:mysql -d wordpress:4.7.3-php7.1-apache
  4. Visit http://0.0.0.0:8000 and configure WordPress

With a Docker compose file

  1. Install Docker for Mac
  2. Save the following text to a ´~/dev /wordpress /website /docker-compose.yml´ file:
  3. Save the following text to a ´~/dev /wordpress /website /docker /wordpress /Dockerfile´ file
  4. Run everything: ´$ docker-compose up´
  5. Visit http://0.0.0.0:8000 and configure WordPress

Connect to the running dbms server from SequelPro

  1. Select the Standard tab
  2. Configure:
  3. Connect

Connect to a running server from a terminal

Example relative to connecting to the running dbms server.

  1. Find out the name of the server:
  2. Connect to the ´website_dbms_1´ server:
  3. Then, for example, find out the server IP:
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How canActivate works for multiple guards

Angular 2 lets developers forbid routes activation by means of a list of guards assigned to the canActivate property of a route definition.

Those guards are classes which implement the CanActivate interface, and the implementation can be a promise, for example when it entails a roundtrip to the server.

The way Angular 2 treats this list of guards is by applying .every(...) to the values of a merge-mapped list of observables.

The list of guards is conceptually the same as a list of promises, and in fact all the guards could be promises because, as we see above, .from(...) is used to initialise check$.

Merge-mapping is exactly what we did in How to convert promises to an observable.

If we now apply .every(...) to that merge-mapped list of promises, we can see how canActivate works for multiple guards.

Notice that the subscription is notified only once, as soon as the resolved promises make it clear what the result would be: the observable emits a false soon after getting the first false, or a true after getting all true-s. So, as expected, canActivate works as a short-circuit-ed AND of each guard of the list, according to the arrival order of values.

Also notice that the values of all the promises keep arriving as promises get resolved, even after the observable has completed. This means that guards intended to be used together in a list of guards should never have side effects (to avoid race conditions). If guard G1 had a side effect of activating route R1, and G2 had another for R2, then canActivate: [G1, G2] would unpredictably activate R1 or R2, depending on which guard completes later.