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C Program to Simulate Linux Cat command

/*  * C program to Simulate Implementation of  Linux *cat* command  * This program will not handle redirection  * you can try to improve this program to handle redirection of file contents  */ #include<stdio.h> #include<string.h> #define MAX_FILE_NAME_CHARS 255 int main(int argc, char *argv[]) {  FILE *fp;  char file_name[MAX_FILE_NAME_CHARS], ch;  int i;  /*   * after creating a.out, rename it as mycat for our own cat command   * and it usage is same as standard cat command   */  if(argc<1){     printf("Usage mycat <filename> \n");     return 0;  }  /*   * cat handles more than one file   * so we need this loop to handle all the files provided   * on command line   */  for(i=1; i<=argc;i++){     /* no need of copy but for understanding purpose, i have created      * string for each file name      */     strncpy(file_name, argv[i], MAX_FILE_NAME_CHARS);     fp=fopen(file_name, "r");     if(fp == NULL) {   
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simple program to create Orphan process

shiv@ubuntu:~/ds/unix$ cat  orp.c /*  * Program to create orphan process @ Linux  * getpid() gives process PID and   * getppid() gives process's parent ID   * here main() process ID is parent id is current shells PID  * once process becomes orphan it is adopted by init process(it's PID is 1)  */   #include<stdio.h> #include<unistd.h> int main() {  pid_t p; /* create child process */  p=fork();  if(p==0) {     /* fork() returns Zero to child */     sleep(10);  }  printf("The child process pid is %d parent pid %d\n", getpid(), getppid()); /*parent/child waits for 20 secs and exits*/  sleep(20);  printf("\nProcess %d is done its Parent pid %d...\n", getpid(), getppid());  return 0; } O/p shiv@ubuntu:~/ds/unix$ ./a.out The child process pid is 2575 parent pid 1922 The child process pid is 2576 parent pid 2575 Process 2575 is done its Parent pid 1922... shiv@ubuntu:~/ds/unix$ Process 2576 is done its Parent pid 1...
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Interactive C program to implement stack using doubly linked list

shiv@ubuntu:~/ds/stack$ cat stack.c /*  * Copy right by Shiv Yaragatti  * you are free to use, modify  and redistribute code on own risk  * Interactive C Program to implement STACK using Doubly linked list  */ #include "header.h" struct stack { int data; struct stack *next; struct stack *prev; }; typedef struct stack *S; /*Push elements in to stack */ void push(S *stack) {   int e;   S temp;   temp=malloc(sizeof(struct stack));   if(!temp){      printf("Can't allocate memory\n");      return;  }  printf("Enter element to push\n");  scanf("%d", &e);  temp->data=e;  if(*stack == NULL){     temp->next = temp->prev = NULL;     *stack=temp;  } else {    temp->next = *stack;    (*stack)->prev = temp;    temp->prev = NULL;    *stack=temp;  } } /* Display elements in the stack */ void display(S s){    S temp;    temp=s;    printf("Elements are ...\n");    while(temp) {     printf("%d\n", temp->data
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