----client.c-----

 /*
Se cere un server si unul sau mai multi clienti.
Fiecare client trimite catre server un nume de fisier text.
Serverul citeste continutul fisierului si ii intoarce clientului
primele trei linii in ordine alfabetica din cadrul fisierului.
*/
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <string.h>
int main(int argc, char* argv[])
{
    int ClientToServer,ServerToClient;
    char *command = malloc(strlen(argv[1])+50);
    memset(command,0,strlen(argv[1])+1);
    strcat(command,argv[1]);
    char *bufferfinal = malloc(300);
    ClientToServer = open("ClientToServer",O_WRONLY);
    ServerToClient = open("ServerToClient",O_RDONLY);
    strcpy(command,"head -n 3 ");
    strcat(command,argv[1]);
    strcat(command,"| sort");
    write(ClientToServer,command,sizeof(strlen(command) + 50));
    read(ServerToClient,bufferfinal,300);
    printf("%s \n",bufferfinal);
    free(command);
    free(bufferfinal);
    close(ClientToServer);
    close(ServerToClient);
return 0;
}


------server.c---------
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <string.h>
int main()
{
    int ClientToServer,ServerToClient;
    ClientToServer = open("ClientToServer",O_RDONLY);
    ServerToClient = open("ServerToClient",O_WRONLY);
    char *command= (char*) malloc (200);
    char *buffer1 = (char*) malloc (100);
    char *buffer2 = (char*) malloc (100);
    char *buffer3 = (char*) malloc (100);
    read(ClientToServer,command,50);
    char *bufferfinal=(char*) malloc (300);
    memset(bufferfinal,0,300);
    FILE *file = popen(command, "r");
    fgets(buffer1,100,file);
    strcpy(bufferfinal,buffer1);
    fgets(buffer2,100,file);
    strcat(bufferfinal,buffer2);
    fgets(buffer3,100,file);
    strcat(bufferfinal,buffer3);
    write(ServerToClient,bufferfinal,sizeof(strlen(bufferfinal) + 10));
    free(command);
    free(buffer1);
    free(buffer2);
    free(buffer3);
    free(bufferfinal);
    close(ClientToServer);
    close(ServerToClient);
return 0;
}