List fonts used in PDF document

If you want to see what fonts have been used in creation of a PDF document, you can use pdffonts utility of poppler-utils package for this. Just type:

  • pdffonts yourfile.pdf

Mount Truecrypt volume without Truecrypt

Some of you may have some old Truecrypt volumes lying around. Truecrypt was a nice and handy utility which is not developed anymore, unfortunately. But you still can mount the volumes created by it.

One way to do it on Ubuntu:

  • sudo cryptsetup tcryptOpen myvol.tc myvol

Where:

  • myvol.tc – the file name of your volume
  • myvol – arbitrary name of the virtual disk to be created

You will be asked for a passphrase, and if you still can remember it, the volume will be mounted under /dev/mapper with the name you provided and will show up as just another disk.


Set auto-increment field value in MySQL

You have a table. The table has a primary key auto-increment numeric ID field. You want to fast-forward the ID to a certain value (which is larger than or equal to the last value the field has).

Example, let the ID of the next entered record be 1000:

  • ALTER TABLE `mytable` AUTO_INCREMENT = 1000;

Validate your domain information

You may want to check if all the information available online in regard of your domain is complete and correct.

In such a case you can go to intodns.com and enter the address of your domain to verify the settings.

One thing you will often see failing is “Reverse MX A records (PTR)” for your mail server, and this is a good way to find out if everything is all right or not.


Video capture VirtualBox from command line

Start and then stop VirtualBox screen recording from command line for a headless Windows 10 session running in virtual machine named Win10:

  • VBoxManage controlvm Win10 videocap on
  • VBoxManage controlvm Win10 videocap off

Generate QR code

  • This simple command will give you an SVG file with QR code vector image in it:
echo "Hello world!" | qrencode --level=H --dpi=300 --type=SVG -o qr.svg
  • If a bitmap is enough, just type:
echo "Hello world!" | qrencode --level=H --dpi=300  -o qr.png

  • Even this simple command will work:
qrencode -o qr.png "Hi!"

  • Change the color from standard black to any if you like:
echo "Hello world!" | qrencode --foreground=808080ff --level=H --dpi=300 --type=SVG -o qr.svg
  • Alpha supported too:
echo "Hello world!" | qrencode --foreground=FFFF00FF --background=0000FF55 --level=H --dpi=300 -o qr.png
echo "Hello world!" | qrencode --foreground=FFFF00FF --background=0000FF55 --level=H --dpi=300 --type=SVG -o qr.svg

		

Remove Apache server signature from footer

By default error pages served by Apache2 contain a line at the bottom, stating version of Apache, OS etc.

If you want it gone, edit /etc/apache/apache2.conf:

  • Add a line:
ServerSignature Off
  • Reload the new configuration:

service apache2 reload

 

P.S. While you are at it you may also add this to tell server not to share more information about itself than necessary:

ServerTokens ProductOnly