How to remove old Linux kernel images from /boot

For RedHat based OS

e.g RHEL or CentOS

Install yum-utils

yum -y install yum-utils

Check current running kernel version

rpm -q kernel

Remove old kernels, but leave the 2 latest ones.

package-cleanup --oldkernels --count=2

Edit /etc/yum.conf and set:


This will delete old kernels automatically but leave the latest two next time you perform a yum update

For Debian based OS

e.g Ubuntu

apt-get -f autoremove

If that doesn’t work, you may need to manually remove files from /boot using rm. Then run update-grub after.

You can always check what kernel is currently loaded by running uname -a

Shutter Actuation Count using gPhoto2

This method can be used to obtain the shutter actuation count on the following cameras:

  • Canon 1D Mark II
  • Canon 50D
  • Canon 5D Mark II
  • Canon 5D Mark III
  • Canon 7D
  • Canon T2i

There may be a few other compatible cameras too. Let me know if you have confirmed another model which works using this method.

Jump to instructions for: Mac | Linux | Windows

Mac OS X

gPhoto2 can be installed using MacPorts or Homebrew. This is how to do it using MacPorts. You’ll need to be connected to the internet while you do this.

  1. Install XCode Developer Tools for your version of OS X from the Apple Developer web site. Skip this if you already have it installed.
  2. Visit the MacPorts web site and download the .pkg installer. Run the installer and follow the instructions and install it to your computer.
  3. Open the Terminal.
  4. Update macports if needed, by running the command sudo port -v selfupdate
  5. Install the gphoto2 package by running the command sudo port install gphoto2
  6. Test whether gphoto2 is properly installed by typing gphoto2 --version
  7. Connect your camera to the USB port, using a USB cable
  8. Wait a few seconds after connecting your camera, and type killall PTPCamera – every time you replug your camera to the computer, you’ll need to type this before using gphoto2. This is needed, to kill any running processes connected to the USB device.
  9. To check the number of actuations, on the attached camera, type gphoto2 --get-config /main/status/shuttercounter
  10. If your camera is compatible, the shutter actuation count will be displayed.


Install gPhoto2 using package manager of our distribution.

For Centos, RHEL and other distributions which use the yum package manager:

yum install gphoto2

For Debian, Ubuntu and other distributions which use the apt package manager:

apt-get install gphoto2

Some Linux distributions may not have gphoto2 as precompiled package in which case you’ll need to download and compile it from source.


Using a LiveCD

This is the simplest way for non tech heads. Download the live CD, I have created and write it to a CD or DVD. You can do this by right clicking on the ISO file in Windows Explorer and selecting “Burn disc image”.

Reboot your computer boot from the CD. To boot your computer from a CD, there is usually key you can press to change the boot device (e.g F12). This usually flashes up on the monitor when it boots up.

Alternatively, you can enter the BIOS settings and change the boot order, and set the CD/DVD drive as the first device.

Once you have rebooted, it should start up in Debian (on the live CD), and a command prompt will be shown along with a message.

live_cdPlug the camera into the computer using a USB cord, some messages may be displayed on scren as you do this. You can check whether the computer has detected the camera by typing dmesg.

To check shutter count, type shuttercounter, to read camera information, you can type camerainfo, this will display information such as the camera’s serial number. These commands shortcuts to the gphoto2 program. You can also run all other gphoto2 commands if needed. See the full features by typing man gphoto2.

Using a Virtual Machine

If you have experience using virtualisation software such as Virtualbox or VMWare Workstation, then another way is to install or use an existing virtual Linux installation of your choice. Install gphoto2 from inside the virtual machine.