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File handling using Shell Scripts

to prepend a line to a file

to develop a temporary file name generator

to compare two files

Requirements:

    Suse Linux, BASH Scripting

Program

(a) Prepending a line to a file

#!/bin/bash

# prepend.sh: Add text at beginning of file.

E_NOSUCHFILE=65

read -p “File: ” file # -p arg to ‘read’ displays prompt.

if [ ! -e "$file" ]

    then [...]

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LSP Lecture Notes

Continue reading Linux System Programming – Lecture notes (upto File systems)

A look at the proc_dir_entry structure
struct proc_dir_entry { unsigned int low_ino; unsigned short namelen; const char *name; // name of our module mode_t mode; // permissions ,who can read and write to it [...]

Continue reading Linux kernel module to add a proc file entry

A Character device driver needs a major number and a minor number. The devices are registered in the Kernel and it lies either in the /dev/ or in the /proc folder.
The following example uses a char device driver with major number 222 and a minor number 0. The name of the device driver namely “new_device”
It [...]

Continue reading Writing a Simple Character Device driver in Linux

Assume there are more number of source files to be compiled using a set of commands everytime is a tedious process. So there is a facility to compile everything at a stretch is by the use of a Makefile.
The makefile can be named as either “Makefile” or “makefile”.
Let me define four files for my simple [...]

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A system call is used by application or user programs to request service from the operating systems. Since the user programs does not have direct access to the kernel whereas the OS has the direct access. OS can access the hardware through system calls only.
The following files has to be modified for implementing a system [...]

Continue reading Implementing a new system call in Kernel version 2.6.32

To demonstrate, let us goto a simple “Hello World” as a module and inserted in to the kernelStep 1Open any editor like vi or gedit in a shell prompt and the type the following/* Name of the file is hello.c */#include <linux/module.h>#include <linux/kernel.h>int init_module(void){printk(KERN_INFO “Hello world.n”);return 0;}void cleanup_module(void){printk(KERN_INFO “Goodbye worldn”);}The above is a simple [...]

Continue reading How to add a new Linux Kernel Module (LKM)