C Program to Implement Cat Command Under Linux

Cat Command

This command is used to display the contents of a text file on the terminal. Using c programing we are now going to implement the function of copy command.

 Program

1. This program should accept command line arguments, so that it behaves similar to the cat command. 
2. The number of arguments should be checked.
3. If the number of arguments are inappropriate a message should be displayed indicating the proper syntax for usage of the command.

 

Code

#include<fcntl.h> //header file for file operations
#include<stdio.h>
#include<stdlib.h>
main(int argc,char*argv[])
{
if(argc!=2){ //checks if two arguments are present
printf("\nThe syntax should as be follows");
printf("\nCommandname filetoread\n");
exit(1);
}
int fdold,count;
char buffer[2048]; //characer buffer to store the bytes
fdold=open(argv[1], O_RDONLY);
if(fdold==-1)
{
printf("cannot open file");
exit(1);
}
while((count=read(fdold,buffer,sizeof(buffer)))>0) //displaying the content
{
printf("%s",buffer);
}
exit(0);
}

C program

Output

[student@localhost grpb]$ gcc cat2.c

[student@localhost grpb]$ ./a.out

The syntax should as be follows

Commandname filetoread

[student@localhost grpb]$ ./a.out test

this is a test document.

[student@localhost grpb]$ ^C

[student@localhost grpb]$

You might also want to see:-

• Copy Command in Linux- C program