enable hibernation in ubuntu 12.04

To enable hibernation in Ubuntu 12.04 (where it is disabled by default), add the following content to the file "/etc/polkit-1/localauthority/50-local.d/com.ubuntu.enable-hibernate.pkla"

[Re-enable hibernate by default]

Identity=unix-user:*

Action=org.freedesktop.upower.hibernate

ResultActive=yes

You may need to run update-grub and to reboot so that the hibernation option shows up in the Shutdown dialog box.

increase font size for Java

To increase the font size for Java applications, add a parameter such as "--fontsize 14" to the option list with which the application is started.

For ThinkingRock this is done by adding "--fontsize 14" to the variable called 'default_options' in the file 'tr.conf'.

printer default color mode

To change the default color mode used when printing in Linux by applications such as Firefox, run first the command "lpoptions -l | grep Color" to get the relevant options. Example output:

CNColorMode/Color Mode: *Auto color mono

To change the default color mode to 'Black & White' for ALL printers run then the following command (it can also be done on a per printer basis using the option '-p' of the command "lpoptions"):

lpoptions -o CNColorMode=mono

The color mode can be set to 'Color' when needed through the print options dialogue.

gpg file encryption

To encrypt files using gpg with symmetric cypher (i.e., password based):

gpg -c FILE_TO_ENCRYPT > ENCRYPTED_FILE

To decrypt the above file (output is stdout):

gpg -d ENCRYPTED_FILE

hibernation error in Ubuntu

Even though swap seemed to be configured properly, I experienced a hibernation error in Ubuntu:

PM: Not enuogh free memory

PM: Error -12 creating hibernation image

The solution was to execute "echo 0 > /sys/power/image_size", which instructs the OS to make the suspend image as small as possible.