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My .emacs file (dot emacs) - Emacs Configuration File

;;; Wrapper to make .emacs self-compiling.
(defvar init-top-level t)
(if init-top-level
  (progn


;; ============================
;; Setup syntax, background, and foreground coloring
;; ============================

(set-background-color "Black")
(set-foreground-color "White")
(set-cursor-color "LightSkyBlue")
(set-mouse-color "LightSkyBlue")
(global-font-lock-mode t)
(setq font-lock-maximum-decoration t)

;; User Information
(setq user-full-name "Karthikeyan Periasamy")
(setq user-mail-address "karthikeyan.periasamy@adckrone.com")

;; Tab using spaces
(setq-default indent-tabs-mode nil)

;; ============================
;; Key mappings
;; ============================
(global-set-key [delete] 'delete-char)
(global-set-key [backspace] 'delete-backward-char)

;;; Key binding for sqitching to next and previous buffer
(global-set-key '[C-tab] 'bs-cycle-next) 

;; use F1 key to go to a man page
(global-set-key [f1] 'man)
;; use F2 to save current buffer
(global-set-key [f2] 'save-buffer)
;; use shift+F2 to save current buffer to other file - "Save As"
(global-set-key [(shift f2)] 'write-file)
;; use F3 to check spelling
(global-set-key [f3] 'ispell-word)
;; use F4 key to kill current buffer
(global-set-key [f4] 'kill-this-buffer)
;; use F5 to compile
(global-set-key [f5] 'compile)
;; use F6 to change file mode to hexl
(global-set-key [f6] 'hexl-mode)
;; use F7 to open files in hex mode
(global-set-key [f7] 'hexl-mode-exit)
;; Now bind the delete line function to the F8 key
(global-set-key [f8] 'nuke-line)
;; use F9 to open files in hex mode
(global-set-key [f9] 'hexl-find-file)
;; use F10 to get help (apropos)
(global-set-key [f10] 'apropos)

;; goto line function C-c C-g
(global-set-key [ (control c) (control g) ] 'goto-line)

;; undo and redo functionality with special module
(require 'redo)
(global-set-key (kbd "C-+") 'redo)

;; keys for buffer creation and navigation
(global-set-key [(control x) (control b)] 'iswitchb-buffer)

;; Backup directory to store all files which end with "~"
;; Enable backup files.
(setq make-backup-files t)

;; Enable versioning with default values (keep five last versions, I think!)
(setq version-control t)

;; Save all backup file in this directory.
(setq backup-directory-alist (quote ((".*" . "~/.emacs.d/backups/"))))

;; Set standard indent to 2
(setq standard-indent 2)

;; ============================
;; Mouse Settings
;; ============================

;; mouse button one drags the scroll bar
(global-set-key [vertical-scroll-bar down-mouse-1] 'scroll-bar-drag)

;; setup scroll mouse settings
(defun up-slightly () (interactive) (scroll-up 5))
(defun down-slightly () (interactive) (scroll-down 5))
(global-set-key [mouse-4] 'down-slightly)
(global-set-key [mouse-5] 'up-slightly)

(defun up-one () (interactive) (scroll-up 1))
(defun down-one () (interactive) (scroll-down 1))
(global-set-key [S-mouse-4] 'down-one)
(global-set-key [S-mouse-5] 'up-one)

(defun up-a-lot () (interactive) (scroll-up))
(defun down-a-lot () (interactive) (scroll-down))
(global-set-key [C-mouse-4] 'down-a-lot)
(global-set-key [C-mouse-5] 'up-a-lot)

;; setup font
(set-default-font
 "-Misc-Fixed-Medium-R-Normal--15-140-75-75-C-90-ISO8859-1")

;; No startup screen, if called with file name
;;(setq inhibit-startup-message t)

;; display the current time
(setq display-time-day-and-date t)
(display-time)

;; Show column number at bottom of screen
(setq column-number-mode 1)

;; show a menu only when running within X (save real estate when
;; in console)
;;(menu-bar-mode (if window-system 1 -1))
(menu-bar-mode nil)

;; alias y to yes and n to no
(defalias 'yes-or-no-p 'y-or-n-p)

;; Set the file end-of-line conversion type of the current buffer to Unix
;;(setq buffer-file-coding-system (coding-system-change-eol-conversion
;;                                 buffer-file-coding-system 'unix))

(set-buffer-modified-p t)
(force-mode-line-update)

;; ===========================
;; Behaviour
;; ===========================

;; Pgup/dn will return exactly to the starting point.
(setq scroll-preserve-screen-position 1)

;; don't automatically add new lines when scrolling down at
;; the bottom of a buffer
(setq next-line-add-newlines nil)

;; scroll just one line when hitting the bottom of the window
(setq scroll-step 1)
(setq scroll-conservatively 1)

;; format the title-bar to always include the buffer name
;;(setq frame-title-format "emacs : %b : "(replace-regexp-in-string "\\([\.]\\)" "_" buffer-file-nam)"")
;;(setq frame-title-format "emacs : %b : %f")
;;(setq frame-title-format '(buffer-file-name "%f" ("%b")))
(setq frame-title-format
   '("Emacs : " (buffer-file-name "%f" (dired-directory dired-directory "%b"))))

;; hide the scroll bar
(scroll-bar-mode nil)

;; turn off the toolbar
(if (>= emacs-major-version 21)
    (tool-bar-mode -1))

;; turn on word wrapping in text mode
;;(add-hook 'text-mode-hook 'turn-on-auto-fill)

;; replace highlighted text with what I type rather than just
;; inserting at a point
(delete-selection-mode t)

;; resize the mini-buffer when necessary
(setq resize-minibuffer-mode t)

;; highlight during searching
(setq query-replace-highlight t)

;; highlight incremental search
(setq search-highlight t)

;; Enable uppercase or lowercase conversions
(put 'downcase-region 'disabled nil)
(put 'upcase-region 'disabled nil)

;; Stop ^M's from displaying in system shell window
(add-hook 'comint-output-filter-functions 'shell-strip-ctrl-m nil t)

;; ===========================
;; Buffer Navigation
;; ============================

;; Iswitchb is much nicer for inter-buffer navigation.
(cond ((fboundp 'iswitchb-mode)                ; GNU Emacs 21
       (iswitchb-mode 1))
      ((fboundp 'iswitchb-default-keybindings) ; Old-style activation
       (iswitchb-default-keybindings))
      (t nil))                                 ; Oh well.

;;cfg
(require 'cmssw-mode)

;; ======
;; C/C++ 
;; ======
(defun my-c-mode-common-hook ()
  (turn-on-font-lock)
  (c-set-offset 'substatement-open 0)
  (c-set-offset 'case-label '+)
;;  (c-set-offset 'arglist-cont-nonempty c-lineup-arglist)
  )
(add-hook 'c-mode-common-hook 'my-c-mode-common-hook)

;; ============================
;; Set up which modes to use for which file extensions
;; ============================
(setq auto-mode-alist
      (append
       '(
         ("\\.h$"             . c++-mode)
         ("\\.dps$"           . pascal-mode)
         ("\\.py$"            . python-mode)
         ("\\.Xdefaults$"     . xrdb-mode)
         ("\\.Xenvironment$"  . xrdb-mode)
         ("\\.Xresources$"    . xrdb-mode)
         ("\\.tei$"           . xml-mode)
         ("\\.php$"           . php-mode)
         ) auto-mode-alist))

;; delete a line
;; First define a variable which will store the previous column position
(defvar previous-column nil "Save the column position")

;; Define the nuke-line function. The line is killed, then the newline
;; character is deleted. The column which the cursor was positioned at is then
;; restored. Because the kill-line function is used, the contents deleted can
;; be later restored by usibackward-delete-char-untabifyng the yank commands.
(defun nuke-line()
  "Kill an entire line, including the trailing newline character"
  (interactive)

  ;; Store the current column position, so it can later be restored for a more
  ;; natural feel to the deletion
  (setq previous-column (current-column))

  ;; Now move to the end of the current line
  (end-of-line)

  ;; Test the length of the line. If it is 0, there is no need for a
  ;; kill-line. All that happens in this case is that the new-line character
  ;; is deleted.
  (if (= (current-column) 0)
    (delete-char 1)

    ;; This is the 'else' clause. The current line being deleted is not zero
    ;; in length. First remove the line by moving to its start and then
    ;; killing, followed by deletion of the newline character, and then
    ;; finally restoration of the column position.
    (progn
      (beginning-of-line)
      (kill-line)
      (delete-char 1)
      (move-to-column previous-column))))


;; Diasble \C-t
(global-unset-key "\C-t")
(global-set-key "\C-t\C-a" 'c-indent-buffer)

;; indent the entire buffer
(defun c-indent-buffer ()
  "Indent entire buffer of C source code."
  (interactive)
  (save-excursion
    (goto-char (point-min))
    (while (< (point) (point-max))
      (c-indent-command)
      (end-of-line)
      (forward-char 1))))

;; set up the compiling options
(setq compile-command "make"
      compilation-ask-about-save nil
      compilation-window-height 10)

))

You have to install some el files.

Pocket Linux Guide

The Linux Documentation Project


This document takes baby steps to explains how to build a small diskette-based GNU/Linux system. This is a very good starting place for Linux newbies to understand how basic linux system works.

Get information about all the network interfaces in linux

This program lists all active network interfaces in the system with associated IP address, MAC address and the subnetmask.

#include <stdio.h>
#include <string.h>
#include <errno.h>
#include <unistd.h>

#define __KERNEL__
#include <asm/types.h>
#undef __KERNEL__

#include <linux/ethtool.h>
#include <linux/sockios.h>

#include <net/if.h>
#include <sys/ioctl.h>
#include <arpa/inet.h>

/* this is straight from beej's network tutorial. It is a nice wrapper
 * for inet_ntop and helpes to make the program IPv6 ready
 */
char *get_ip_str(const struct sockaddr *sa, char *s, size_t maxlen)
{
  switch(sa->sa_family) {
    case AF_INET:
      inet_ntop(AF_INET, &(((struct sockaddr_in *)sa)->sin_addr), s, maxlen);
      break;

    case AF_INET6:
      inet_ntop(AF_INET6, &(((struct sockaddr_in6 *)sa)->sin6_addr), s, maxlen);
      break;

    default:
      strncpy(s, "Unknown AF", maxlen);
      return NULL;
  }

  return s;
}

int main (int argc, char **argv)
{
  char          buf[1024] = {0};
  struct ifconf ifc = {0};
  struct ifreq *ifr = NULL;
  int           sck = 0;
  int           nInterfaces = 0;
  int           i = 0;
  struct ifreq ifr_subnet;
  struct sockaddr *addr_subnet = NULL;

  /* Get a socket handle. */
  sck = socket(AF_INET, SOCK_DGRAM, 0);
  if(-1 == sck) {
    perror("socket");
    return 1;
  }

  /* Query available interfaces. */
  ifc.ifc_len = sizeof(buf);
  ifc.ifc_buf = buf;
  if(-1 == ioctl(sck, SIOCGIFCONF, &ifc)) {
    perror("ioctl(SIOCGIFCONF)");
    close (sck);
    return 1;
  }

  /* Iterate through the list of interfaces. */
  ifr = ifc.ifc_req;
  nInterfaces = ifc.ifc_len / sizeof(struct ifreq);
  for(i = 0; i < nInterfaces; i++)
  {
    struct ifreq *item = &ifr[i];

    /* Show the device name and IP address */
    struct sockaddr *addr = &(item->ifr_addr);
    char ip[INET6_ADDRSTRLEN];
    printf("%s: IP %s",
           item->ifr_name,
           get_ip_str(addr, ip, INET6_ADDRSTRLEN));

    /* Get the MAC address */
    if(-1 == ioctl(sck, SIOCGIFHWADDR, item)) {
      perror("ioctl(SIOCGIFHWADDR)");
      close (sck);
      return 1;
    }

    /* display result */
    printf(", MAC %.2x:%.2x:%.2x:%.2x:%.2x:%.2x ",
           (unsigned char)item->ifr_hwaddr.sa_data[0],
           (unsigned char)item->ifr_hwaddr.sa_data[1],
           (unsigned char)item->ifr_hwaddr.sa_data[2],
           (unsigned char)item->ifr_hwaddr.sa_data[3],
           (unsigned char)item->ifr_hwaddr.sa_data[4],
           (unsigned char)item->ifr_hwaddr.sa_data[5]);

    /* Reset the memory allocated for ifreq */
    memset (&ifr_subnet, 0, sizeof (struct ifreq));

    /* Update interface name into ifreq */
    strcpy (ifr_subnet.ifr_name, item->ifr_name);

    /* Call ioctl function */
    if(-1 == ioctl (sck, SIOCGIFNETMASK, &ifr_subnet ))
    {
      perror("ioctl(SIOCGIFNETMASK)");
      close (sck);
      return 1;
    }
    addr_subnet = &(ifr_subnet.ifr_addr);
    printf("SubnetMask: %s\n", get_ip_str(addr_subnet, ip, INET6_ADDRSTRLEN));
  }

  close (sck);
  return 0;
}

Reference: http://www.adamrisi.com/?p=84

Simple PING implementation in C

#include <netinet/in.h>
#include <netinet/ip.h>
#include <netinet/ip_icmp.h>
#include <arpa/inet.h>
#include <netdb.h>
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <sys/signal.h>
#include <string.h>

#define DEFDATALEN      56
#define MAXIPLEN        60
#define MAXICMPLEN      76

static char *hostname = NULL;

static int in_cksum(unsigned short *buf, int sz)
{
  int nleft = sz;
  int sum = 0;
  unsigned short *w = buf;
  unsigned short ans = 0;
  
  while (nleft > 1) {
    sum += *w++;
    nleft -= 2;
  }
  
  if (nleft == 1) {
    *(unsigned char *) (&ans) = *(unsigned char *) w;
    sum += ans;
  }
  
  sum = (sum >> 16) + (sum & 0xFFFF);
  sum += (sum >> 16);
  ans = ˜sum;
  return (ans);
}

static void noresp(int ign)
{
  printf("No response from %s\n", hostname);
  exit(0);
}

static void ping(const char *host)
{
  struct hostent *h;
  struct sockaddr_in pingaddr;
  struct icmp *pkt;
  int pingsock, c;
  char packet[DEFDATALEN + MAXIPLEN + MAXICMPLEN];
  
  if ((pingsock = socket(AF_INET, SOCK_RAW, 1)) < 0) {       /* 1 == ICMP */
    perror("ping: creating a raw socket");
    exit(1);
  }
  
  /* drop root privs if running setuid */
  setuid(getuid());
  
  memset(&pingaddr, 0, sizeof(struct sockaddr_in));
  
  pingaddr.sin_family = AF_INET;
  if (!(h = gethostbyname(host))) {
    fprintf(stderr, "ping: unknown host %s\n", host);
    exit(1);
  }
  memcpy(&pingaddr.sin_addr, h->h_addr, sizeof(pingaddr.sin_addr));
  hostname = h->h_name;
  
  pkt = (struct icmp *) packet;
  memset(pkt, 0, sizeof(packet));
  pkt->icmp_type = ICMP_ECHO;
  pkt->icmp_cksum = in_cksum((unsigned short *) pkt, sizeof(packet));
  
  c = sendto(pingsock, packet, sizeof(packet), 0,
             (struct sockaddr *) &pingaddr, sizeof(struct sockaddr_in));
  
  if (c < 0 || c != sizeof(packet)) {
    if (c < 0)
      perror("ping: sendto");
    fprintf(stderr, "ping: write incomplete\n");
    exit(1);
  }
  
  signal(SIGALRM, noresp);
  alarm(2);                                     /* give the host 5000ms to respond */
  /* listen for replies */
  while (1) {
    struct sockaddr_in from;
    size_t fromlen = sizeof(from);
    
    if ((c = recvfrom(pingsock, packet, sizeof(packet), 0,
                      (struct sockaddr *) &from, &fromlen)) < 0) {
      if (errno == EINTR)
        continue;
      perror("ping: recvfrom");
      continue;
    }
    if (c >= 76) {                   /* ip + icmp */
      struct iphdr *iphdr = (struct iphdr *) packet;
      
      pkt = (struct icmp *) (packet + (iphdr->ihl << 2));      /* skip ip hdr */
      if (pkt->icmp_type == ICMP_ECHOREPLY)
        break;
    }
  }
  printf("%s is alive!\n", hostname);
  return;
}

int main ()
{
  ping ("192.168.1.2");

}

Reference: http://www.koders.com/c/fid30EA22902AFF5800481BBC6F65DADCDAF92D6E37.aspx

Add new option in configure script in autobuild system

Example:
To get a new option "--with-unit-test" when you run "./configure --help"

Optional Packages:
  --with-unit-test        Create binary to unit test the library package
                          (default is no)

add the following block in "configure.ac"

AC_MSG_CHECKING([--with-unit-test])
AC_ARG_WITH(unit-test,
        AC_HELP_STRING([--with-unit-test], [Create binary to unit test the library package (default is no)]),
        [unittest="yes"],
        [unittest="no"]
)
AM_CONDITIONAL(UNIT_TEST, test "$unittest" = "yes")
AC_MSG_RESULT([$unittest])

and you Makefile.am will look like this,

bindir = $(prefix)/usr/local/bin
libdir = $(prefix)/usr/local/lib

if UNIT_TEST
bin_PROGRAMS = unittest
unittest_SOURCES = source1.c \
                      Source2.c
unittest_CFLAGS = -I@top_srcdir@/include \
                     -DUNIT_TEST
unittest_LDFLAGS =
else
lib_LTLIBRARIES           = libunittest.la
libunittest_la_SOURCES = source2.c \
                         source3.c
libunittest_la_CFLAGS = -I@top_srcdir@/include
libunittest_la_LDFLAGS = -version-info 0:1:0
endif

and take care of UNIT_TEST macro check in the source code.

How to create self-Extracting script

It involves 3 steps,

1. Create Payload
2. Create Installer script
3. Packaging

Create Payload:
This is a tar ball  in which all the installable binaries, libraries, script files, configuration files, etc will be placed in the same file hierarchy of the target board considering the base directory of the tar ball is the installation directory on the target board.

periask@ubuntu:~$ mkdir -vp packaging/Payload
mkdir: created directory `packaging
mkdir: created directory `packaging/Payload'
periask@ubuntu:~$ cd packaging/Payload
periask@ubuntu:~/packaging/Payload$ cp --preserve=mode -rl <installables> .
periask@ubuntu:~/packaging/Payload$ tar zcf ../Payload.tar.gz .
periask@ubuntu:~/packaging/Payload$ cd ..
periask@ubuntu:~/packaging$

Create Installer Script:

Copy the below content and create "installer" file in "packaging" directory.

#!/bin/bash

# Get the starting point of the tar ball
SKIP=`awk '/^__ARCHIVE__/ { print NR + 1; exit 0; }' $0`

# Do pre-installation steps here.

# Extracting the tar ball Which is appended to this file
tail -n "+$SKIP" $0 >/dev/null 2>&1
if [ $? -eq 0 ]; then
    tail -n +$SKIP $0 | gunzip -c | tar -C / -xvf -
else
    tail +$SKIP $0 | gunzip -c | tar -C / -xvf - 
fi

# Do post-installation steps here.

exit 0

__ARCHIVE__

Note: There should not be any space  after "__ARCHIVE__" and should be a new line after "__ARCHIVE__".

Packaging:

Concatenate the file "installer" and "Payload.tar.gz" and create the package file.

periask@ubuntu:~/packaging$ cat installer Payload.tar.gz > Package-Version.sh
periask@ubuntu:~/packaging$ chmod +x Package-Version.sh

Installer for your package "Package-Version.sh" is ready.

Source: Linux Journal