Category: Programming

Upgrade ruby gem
To upgrade a ruby gem run
```
gem update --system VERSION_HERE
```
Example
```
gem update --system 1.3.7
```
See Ruby
October 11, 2020
How to Install Visual Studio Code Server
Code Server allow you to run Microsoft Visual Studio Code in the browser. Code Server runs on a remote web server, you can access it by going to special url. This allow business to move development environment to cloud, deploy new developer environment on cloud or on premise server quickly with automation tools. Developers can access their secure work environment from any device that have a web browser and internet connection. This is helpful when employees work remotely so all code/files stay on the cloud instead of developers local computer.

https://github.com/cdr/code-server

Install Code Server

You can download latest version of Code Server from

https://github.com/cdr/code-server/releases

To install Code Server 3.5.0, run
```
cd /usr/local/src
wget https://github.com/cdr/code-server/releases/download/v3.5.0/code-server-3.5.0-linux-amd64.tar.gz
tar xvf code-server-3.5.0-linux-amd64.tar.gz
mv code-server-3.5.0-linux-amd64 /usr/local
```
To start code server, run
```
/usr/local/code-server-3.5.0-linux-amd64/bin/code-server --bind-addr 0.0.0.0:10090
```
This will make code server listen to port 10090 on all IP address configured on the server.

You can access the code server at
```
http://SERVER_IP_HERE:10090
```
You can find password to login in file ~/.config/code-server/config.yaml

If you don’t want to auto start code server on server boot, you can run the command in tmux or screen.

Enable SSL for Code Server

You can get Free SSL certficate using LetsEncrypt.

Once you got SSL certficate for your domain, you need to do the following. This this example, i use lab.serverok.in domain and user “boby”.

Copy SSL to users directory, so code server can access it.
```
mkdir -p /home/boby/.config/code-server
cp /etc/letsencrypt/live/lab.serverok.in/fullchain.pem  /etc/letsencrypt/live/lab.serverok.in/privkey.pem /home/boby/.config/code-server
chown -R boby:boby /home/boby/.config
```
Create Systemd service file to autostart code server

create file
```
vi /lib/systemd/system/code-server.service
```
Add
```
[Unit]
Description=code-server

[Service]
Type=simple
ExecStart=/usr/local/code-server-3.5.0-linux-amd64/bin/code-server --bind-addr 0.0.0.0:10090 --cert /home/boby/.config/code-server/fullchain.pem  --cert-key  /home/boby/.config/code-server/privkey.pem
Restart=always
User=boby
Group=boby
WorkingDirectory=/home/boby/

[Install]
WantedBy=multi-user.target
```
Start Code Server

To start code server, run a user root
```
systemctl start code-server
```
To get Password to login to code server, run
```
root@lab:~# cat /home/boby/.config/code-server/config.yaml 
bind-addr: 127.0.0.1:8080
auth: password
password: dd39e18a466d89b6579169ae
cert: false
root@lab:~# 
```
If you want to change password, you can edit the file and restart code server with
```
systemctl restart code-server
```
Update SSL

LetsEncrypt SSL expire every 90 days and renew the SSL certificate every month. We will copy over the SSL certficate using a cronjob and restart code server every week.

create file
```
vi /usr/local/bin/code-server-update-ssl
```
Add following
```
#!/bin/bash

cp /etc/letsencrypt/live/lab.serverok.in/fullchain.pem  /etc/letsencrypt/live/lab.serverok.in/privkey.pem /home/boby/.config/code-server
chown boby:boby /home/boby/.config/code-server/fullchain.pem
chown boby:boby /home/boby/.config/code-server/privkey.pem
systemctl restart code-server
```
Make it executable
```
chmod 755 /usr/local/bin/code-server-update-ssl
```
Create cron job
```
crontab -e
```
Add
```
@weekly /usr/local/bin/code-server-update-ssl > /dev/null 2>&1
```
October 10, 2020
PHP APC Cache
APC Cache is an open source opcode caching module for PHP. You can find documentation for APCu at

https://www.php.net/manual/en/book.apcu.php
See PHP
June 2, 2020
dotnet

How to install .NET SDK in Ubuntu 20.04
Install .NET SDK on Ubuntu 20.04
How to create .NET console program

April 19, 2020
HTTP 301 Redirect using PHP
You can use the PHP header() function to do redirect.

To do 301 redirect, use
```
header('Location: https://new-url/', true, 301);
exit;
```
For 302 redirect, use
```
header('Location: https://new-url/');
exit;
```
If you need to redirect a site to a new site while keeping the same URL structure, you can use
```
$newUrl = "https://NEW-URL-HERE" . $_SERVER['REQUEST_URI'];
header("HTTP/1.1 301 Moved Permanently");
Header("Location: $newUrl");
exit;
```
Back to redirect
February 8, 2020
PHP PECL extension
PECL is a repository for PHP Extensions, providing a directory of all known extensions and hosting facilities for downloading and development of PHP extensions.

https://pecl.php.net/packages.php

To install a PECL extension, run
```
pecl install pecl_http
```
To install a specific version, run
```
pecl install pecl_http-3.2.3
```
January 5, 2020

Redirect a site to HTTPS using PHP

This PHP script will redirect website visitors to HTTPS (SSL) URL. You can add this in your index.php of the website

if (empty($_SERVER['HTTPS']) || $_SERVER['HTTPS'] != "on" ) {
    header("HTTP/1.1 301 Moved Permanently");
    $newUrl = "https://" . $_SERVER['HTTP_HOST'] . $_SERVER['REQUEST_URI'];
    Header("Location: $newUrl");
    exit;
}

To redirect visitors to a new URL using PHP, use the following PHP code

$newUrl = "https://NEW-URL-HERE" . $_SERVER['REQUEST_URI'];
header("HTTP/1.1 301 Moved Permanently");
Header("Location: $newUrl");
exit;

You can also use Apache mod_rewrite .htacess to do the redirection.

July 18, 2019

Gem – Package Manager for Ruby
gem is package manager for Ruby.

To get list of all install packages, run
```
gem list
```
To install a package, run
```
gem install PACKAGE_NAME
```
To uninstall a package, run
```
gem uninstall PACKAGE_NAME
```
To search for a package, run
```
gem search PACKAGE_NAME
```
gem install error libxslt is missing

See Ruby
February 26, 2019
GoLang Hello World
Create a file 1.go with following content
```
package main

import "fmt"

func main() {
	fmt.Println("My First GoLang Program")
}
```
To run the program, use command
```
go run 1.go
```
January 5, 2019
golang

Installing golang on Ubuntu 18.04
GoLang Hello World

January 5, 2019
Installing golang on Ubuntu 18.04
To install golang on Ubuntu 18.04, run
```
apt install golang -y
```
January 5, 2019
PHP running system commands with exec
To execure a system command on a server, use PHP exec function.

For example
```
<?php

@exec("nslookup yahoo.com 2>&1", $result);

print_r($result);
```
December 31, 2018

Category: Programming

Install Code Server

Enable SSL for Code Server

Create Systemd service file to autostart code server

Start Code Server

Update SSL