Creating pencil sketch of an image in linux using pinta

Here is how we can create the pencil skethc of any image using the software pinta in linux.

If you do not have pinta installed, you can install it using the package manager. In debian based systems we can run

apt-get install pinta

Now launch pinta, In debian it would be listed under Applications->graphics, might be different for other distros.

Now click on

file->open



Browse the image for which the pencil sketch is need to be made, and click on open. Let us take the image of our beloved tux for creation of a pencil sketch.



Now click on

Effects->Artistic->Pencil Sketch.



The following menu will pop.



Pencil tip size: Higher this value more dark the image looks.
Color range: Higher the value more mix of white and balck will appear in the image.

As the change in these options are done, the changes in the image can be seen in the backgroud. Which ever values are satisfctory click ok for those and the pencil sketch image is ready. Here is the pencil sketch image of tux.

Adding fog effect using gimp

Here is how we can add the fog effect to any image, using gimp.

Lunch gimp and click on

file->open

Browse to the photo that is to which the fog effect has to be added and click on open.

In the example we will use the following image to add the fog effect.



Now click on

filter->render->cloud->fog



This will launch a window as shown below.



The options available are

Name: Layer Name Color: The color of the fog Turbulence: How much fog should be added to the image Opacity: How opaque should the fog be.

Click on OK and wait for gimp to do the magic.

After applying the fog, the above image looks as below.

Quiz based on chapter-4 of book linux device drivers 3rd ed

Quiz on chapter-4 of book linux device drivers 3rd ed

1. Which of the following config options need to be enabled to be able to debug kernel.

CONFIG_DEBUG_KERNEL
CONFIG_USB
CONFIG_EXT4
CONFIG_DBG


2. The first argument passed to printk specifies the

loglevel for the message to be printed
terminal number for the message to be printed
userid of the current user
line number in which the message has to be printed


3. The command that can be used to view the kernel logs from user space is

kmesg
dmesg
kmsg
dmsg


4. The function create_proc_read_entry returns a pointer to

struct proc_dir
struct proc_entry
struct proc_dir_entry
struct proc


5. The seq file interface is used for

logging errors in kernel space
Creating a /proc entry
Passing user information to kernel
Passing kernel information to user space


6. output of strace shows

The function calls made by user applications
The system calls made by a user application
The kernel modules used by a user application
The various applications running in the user space.


7. In a kernel oops message EIP points to

The address of the faulty instruction
The faulty instruction
The faulty line in the user code
The faulty user application


8. While using gdb for kernel debugging the kernel core file used passed to gdb is

/proc/core
/proc/kcore
/dev/core
/dev/kcore


9. Which of the following keys will launch the kdb

sysrq
pause
shift
del


10. To use kgdb we need two systems connected by a serial cable

True
False
depends on kernel version
depends on kgdb version

Script to download the latest linux kernel

Here is a script that will download the latest kernel source kernel.org. THe script works on the current html page of kernel.org and might break if anything is changed in the page of kernel.org.

latest_kernel:

#!/bin/bash latest_kernel () { latest_link=$(grep -A 1 "latest_link" page | tail -1 | cut -d "\"" -f 2 | cut -d "." -f 2-) prefix=https://www.kernel.org link=$prefix$latest_link for((i=0;i<=2;i++)) do echo -e "\n \n downloading from $link \n \n" wget -c $link comp=$? if [ $comp -eq 0 ] then echo "Download complete" rm page exit else echo "Trying again" fi done echo "Download failed" rm page } wget -O page wget -O page www.kernel.org latest_kernel

save the script as latest_kernel.sh.

Run the script by giving it execute permission. Please note that the from which ever folder the script is executed the user running the script needs to have the permission to create and delete files and folders as the script places the downloaded source in the same folder and also creates a temporary file and deletes it.

$ chmod 777 latest_kernel.sh $ ./latest_kernel.sh --2013-08-01 22:23:17-- http://wget/ Resolving wget... failed: Name or service not known. wget: unable to resolve host address “wget” --2013-08-01 22:23:17-- http://www.kernel.org/ Resolving www.kernel.org... 149.20.4.69, 198.145.20.140 Connecting to www.kernel.org|149.20.4.69|:80... connected. HTTP request sent, awaiting response... 301 Moved Permanently Location: https://www.kernel.org/ [following] --2013-08-01 22:23:18-- https://www.kernel.org/ Connecting to www.kernel.org|149.20.4.69|:443... connected. HTTP request sent, awaiting response... 200 OK Length: 17430 (17K) [text/html] Saving to: “page” 100%[===================================================================================>] 17,430 27.8K/s in 0.6s 2013-08-01 22:23:20 (27.8 KB/s) - “page” saved [17430/17430] FINISHED --2013-08-01 22:23:20-- Downloaded: 1 files, 17K in 0.6s (27.8 KB/s) downloading from https://www.kernel.org/pub/linux/kernel/v3.x/linux-3.10.4.tar.xz --2013-08-01 22:23:20-- https://www.kernel.org/pub/linux/kernel/v3.x/linux-3.10.4.tar.xz Resolving www.kernel.org... 149.20.4.69, 198.145.20.140 Connecting to www.kernel.org|149.20.4.69|:443... connected. HTTP request sent, awaiting response... 200 OK Length: 73187712 (70M) [application/x-xz] Saving to: “linux-3.10.4.tar.xz” 100%[===================================================================================>] 73,187,712 97.3K/s in 11m 18s 2013-08-01 22:34:40 (105 KB/s) - “linux-3.10.4.tar.xz” saved [73187712/73187712] Download complete

Thus we can see from the ouput that the latest kernel 3.10.4 has been downloaded. In case the download gets interrupted then the script will retry the download 3 times before quitting with the message of "Download Failed".