如何通过系统调用写入UNIX终端？

Question

I have been working on 'C' for quite sometime.

I would like to say 'Hello ' to my team mates when they open the terminal and logon for the first time of the day

I found this post a useful one

Not able to read data from other terminal using read() system call

How can I write to others terminal (because, in pts/n - n will differ from person to person) and say the welcome message ?

Answer 1

This possibly is the simplest of programs you can get with out much validations and error handling etc.

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>


int main ( int argc, char *argv[] )
{
    if ( argc != 3 ) {
        fprintf(stderr, "usage : msend \"terminal\" \"message\" ");
        exit(1);
    }

    char filePath[256] = {0,};

    if ( strncmp( argv[1], "/dev/pts", strlen("/dev/pts") ) )  {
        sprintf( filePath, "/dev/%s" , argv[1] );   
    } else {
        sprintf( filePath, "%s", argv[1] );
    }

    int fd = open( filePath , O_RDWR , O_APPEND);

    write( fd, argv[2], strlen(argv[2]) );

    return 0;
}

Try building on top of this.