First create a file in your Home directory by name seqno.txt,just write one character the digit one( 1 ) into the file and save it.This program reads the number from the file , increments it then writes back the incremented value back into the file. This sequence o program is used to control print jobs in UNIX

1. /* First create a file in your Home directory by name seqno.txt,just write one
character the
digit one( 1 ) into the file and save it.This program reads the number from the
file , increments it
then writes back the incremented value back into the file.
This sequence o program is used to control print jobs in UNIX */
#define PATH "/home/hackintoshrao/seqno.txt" //Enter the path of your home
directory here
#include<stdio.h>
#include<stdlib.h>
#include<fcntl.h>
int main()
{
int i,fd,n;
char buf[100];
if((fd=open(PATH,O_RDWR))==-1) //open the file to read and write
fprintf(stderr,"Error opening file",50);
read(fd,buf,100) ;//read the number from the file
n=sizeof(buf);
buf[n]='0'; //terminate with null characters to use sscanf
sscanf(buf,"%dn",&i); //read the number from the string into integer i
i++;//increment the value
sprintf(buf,"%d",i); //write the incremented value into the string
lseek(fd,0,SEEK_SET);
/*set the write pointer to the beginning of the file(the file position was
altered
by the read function after reading the first character*/
write(fd,buf,sizeof(buf));//write the incremented value back to the file
close(fd);
return 0;
}