Author Archives: chirale

10 steps to install LyX on Windows

Here the steps to install LyX on Windows:

  1. Download MiKTeX to provide LaTeX (usually the 64bit version)
  2. Select the installation directory and remember the path
  3. Complete the installation procedure
  4. Download and install LyXWinInstaller
  5. Press Next until a dictionary list is presented: add dictionaries for your languages
  6. Before installing the MiKTeX will be shown:
  7. Click Install and proceed.
  8. You should get an Update popup for MiKTeX, check the connection settings and then proceed and click Next to update all packages
  9. After the update close the MiKTeX popup and wait to LyX installation to finish: it should take minutes, to see progress click “See details” so you can see it’s not hanged up but it’s simply fetching different templates you can use later.
  10. Select Launch LyX and start using LyX

Now you can enjoy LyX for Windows to create PDF using LaTeX without having to deal with the usual formatting hassles of a WYSIWYG editor.

If you’re a beginner or you want to jog your memory about LyX select Help > Tutorial.

To export to PDF you can user File > Export and then select PDF LuaTeX or PDF XeTeX. In my case LuaTeX generate larger document than XeTeX but both are nicer than those generated by ps2pdf.


Spellcheck web page by address

Looking for error in web pages can be very boring. I’ve tried some online tools but they seems too old, unsatisfying or premium only so I go to a 3 days programming marathon and I put online a brand new tool to do the job I need.

Go to Spellcheck This! and paste the URL address of the page you want to check and get the page checked for Deutsch, US English, Español, Français and Italiano.

The tool try to understand the language of the page and then return the result highlighting in different ways typing errors, names and acronyms on paragraphs, heading tags, tables and blockquotes.


It’s very far from perfect but it speeds up the spell check job. I’ve already spotted and fixed some minor errors on Wikisource and Wikipedia on very long texts.

Comment if you use and like it!

Programming note: Spellcheck This! is build with Python upon Flask and PyEnchant on the backend and Dust.js, jQuery and Foundation 6 Essential for the frontend.

Linux: MySQLdb on virtualenv with –no-site-packages

In the past it was difficult to get MySQL working on virtualenv without using system packages. Now you can have a real separated environment with simple steps:

  1. Follow this guide to install virtualenv using this command:
    virtualenv myproject --no-site-packages

    This command will install a new virtualenv inside a new directory myproject created by the command itself.

  2. Activate virtualenv:
    source myproject/bin/activate
  3. Upgrade setuptools
    pip install pip --upgrade
  4. You can now install MySQLdb, inside the package MySQL-python:
    pip install MySQL-python
  5. Now do a simple test trying to connect to an existing database:
    import MySQLdb
    db = MySQLdb.connect(host="localhost",   # your host, usually localhost
                         user="chirale",         # your username
                         passwd="ITSASECRET",    # your password
                         db="chiraledb")         # name of the database
    cursor = conn.cursor()
    cursor.execute("SELECT VERSION()")
    row = cursor.fetchone()
    print "server version:", row[0]

Tested on CentOS 7, Python 2.7

Tip: If you are starting to create a database doing all the dirty work alone you’ve to give SQLAlchemy a try. You can use like an ORM or a lower level as you wish.

See also

The Hitchhiker’s Guide to Python
Simple MySQLdb connection tutorial

About the same topic

Python: MySQLdb on Windows virtualenv (w. figures)

Python: MySQLdb on Windows virtualenv (w. figures)

If you have a virtualenv on Windows and you want to add MySQLdb support via mysql-python, read this before spending hours of your life to figure why it doesn’t and it will never work.

1) Install MySQL for Python selecting the same Python version of the virtualenv


2) From site-packages directory above, copy the selected files:


3) (optional) On PyCharm, look for virtualenv site-packages inside the path marked with the arrow:


4) Open your virtualenv console ad do:

import MySQLdb

MySQL for Python is now installed on your virtualenv.

About the same topic
How to Install MySQLdb in PyCharm, Windows
Linux: MySQLdb on virtualenv with –no-site-packages


HTTPS, encrypt via SSL / TLS

Free SSL certificates and how to install on nginx in 10 steps

Here how you can get free SSL cerificates using Let’s Encrypt. Forget about the expire of certificates using the auto-renewal script. A complete reference to install a Let’s Encrypt certificate is this Digital Ocean’s howto. Here there’s a quick guide based on it, plus some additional suggestions. Here we go!

The following code download the script and make it executable. (1)

cd /usr/local/sbin
chmod a+x /usr/local/sbin/certbot-auto

The following code create a path for ssl certificate. Change /usr/local/etc/my/files/path/ssl_cert with a path for where you’ll store certificates, you can select a path not in your document root. (2)

mkdir /usr/local/etc/my/files/path/ssl_cert

Now edit your /etc/nginx/conf.d/mysites.conf and add this into the server {…} directive to make available url (3):

        location ^~ /.well-known {
                alias /usr/local/etc/my/files/path/ssl_cert/.well-known;
                allow all;

Now execute the script to install certificates for your domains. Remember to use the command with -d domain-without-www -d www-domain in this order. (4)

  1. Install all needed dependencies for your system (via yum on RedHat based distro and apt on Debian based)
  2. Generate a valid certificate
certbot-auto certonly -a webroot --webroot-path=/usr/local/etc/my/files/path/ssl_cert -d -d -d -d

An auto check will be performed and you will get a Congratulation message.

Now generate a strong Diffie-Hellman group with this command (5):

openssl dhparam -out /etc/ssl/certs/dhparam.pem 2048

Check syntax and if ok reload the nginx server to apply changes and . (6)

nginx -t
systemctl reload nginx


A certificate will be valid for a short period of time, e.g. 3 months.

To auto-renew the certificate for all of your domains, you should add the auto-renewal command to cron (7):

30 2 * * 0 /usr/local/sbin/certbot-auto renew >> /var/log/le-renew.log
35 2 * * 0 /etc/init.d/nginx reload

The command will be executed every sunday night, between 2.30-2.35am, when the certificate will be checked to be renewed if needed.

Enable SSL on nginx

To enable SSL on nginx, if you have already a mysite.conf file mapped for uncrypted connection on port 80. Inside the /etc/nginx/conf.d directory, copy the file as mysite_ssl.conf and:

Change all occurrences of:

listen 80;


listen 443 ssl;

In this way nginx will listen to 443 port on SSL. Ensure you have this port available externally (firewall and/or Selinux audit2allow). (8)

In the original file, mysite.conf, you can delete all entries but you have to keep the well-know part (step 3). This will avoid errors by Let’s Encrypt script.

Add and enable cyphers. Here there’s a good cyphers list, reliable for compatibile but secure using TLS only. (9)

server {
    # the port your site will be served on
    listen      443 ssl;
    # the domain name it will serve for
    server_name; # substitute your machine's IP address or FQDN
    ssl_certificate /etc/letsencrypt/live/;
    ssl_certificate_key /etc/letsencrypt/live/;
    ##### Cyphers and SSL fine tuning #####
    ssl_protocols TLSv1 TLSv1.1 TLSv1.2;
    ssl_prefer_server_ciphers on;
    ssl_dhparam /etc/ssl/certs/dhparam.pem;
    ssl_session_timeout 1d;
    ssl_session_cache shared:SSL:50m;
    ssl_stapling on;
    ssl_stapling_verify on;
    add_header Strict-Transport-Security max-age=15768000;
    ##### END Cyphers and SSL fine tuning #####
    # charset     utf-8; etc...

Test nginx syntax with:

nginx -t

and then reload nginx to apply changes (10), on CentOS:

systemctl restart nginx

Transfer files from iPad to Windows wireless w/o cloud in 10 steps

10 steps to transfer files without using iCloud or other cloud services: an iPad and Windows are all you need.


  • Windows (tested on Windows 7)
  • Wi-fi router


  1. Create a new folder ipadshare on your disk (even removable) to host files
  2. Right click on the folder > Share with... > Specific users…
  3. Click on the bottom arrow on the dropdown > Create a new user > Another account (second to last element) > Create new account
  4. Type the name and the password for the new user (no Administrator)
  5. Back to the Share with…> Specific people… window:
    1. Select the new user from the dropdown
    2. Click on Add
    3. Give her read/write access
    4. Save


  1. Connect to the same Wi-fi router your Windows PC is connected to
  2. From home screen go to Settings > Display and Brightness > Auto-Lock > Never
  3. From App Store, Install and open FileExplorer (free)
  4. Enter into Local or Photos
    1. Tap Edit and then Select all on the bottom (or select one element at time)
    2. Tap Copy into
  5. Select Connections > ipadshare. Type user and password and then tap Save.

Do not lock the screen during the transfer process since otherwise FileExplorer free can freeze. After the transfer, check the transferred items before deleting them from the ipad.

Photo by

Memory Error on pip install (SOLVED)

Memory Error when using pip install on Python can emerge both from command line or from a IDE like PyCharm, usually when the package size is big.

When you try to install a python package with pip install packagename but it fails due to a Memory Error, you can fix it in this way:

  1. Go to your console
  2. Optional: if your application is into a a virtual environment activate it
  3. pip install packagename --no-cache-dir

The package will now be downloaded with the cache disabled (see pip –help).

Thanks to David Wolever