//Pipe commands #4 din setul CV
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#fisierul cv1.1.c
---------------------------------------------------------------------------------

#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <errno.h>

int main()
{
    pid_t pid;
    int p[2];

    if(-1 == pipe(p) )
    {
        fprintf(stderr, "Eroare: nu pot crea un canal anonim, errno=%d\n",errno);  perror("Cauza erorii");  exit(1);
    }

    if(-1 == (pid=fork()) )
    {
        perror("Eroare: nu am putut crea un fiu. Cauza erorii");  exit(2);
    }

    if(pid == 0)
    {
        if(-1 == dup2(p[1],1) )
        {
            perror("Eroare: redirectarea iesirii standard in fiu a esuat. Cauza erorii");  exit(3);
        }

        execlp("w", "w", "-h", NULL);
        perror("Eroare la execlp() in fiu. Cauza erorii");  exit(4);
    }
    else
    {
        close(p[1]);

        if(-1 == dup2(p[0],0) )
        {
            perror("Eroare: redirectarea intrarii standard in parinte a esuat. Cauza erorii");  exit(5);
        }

        execl("cv1.2.exe", "cv1.2", NULL);
        perror("Eroare la execl() in parinte. Cauza erorii");  exit(6);
    }

    return 0;
}

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#fisierul cv1.2.c
----------------------------------------------------------------------

#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <errno.h>

int main()
{
    pid_t pid;
    int p[2];

    if(-1 == pipe(p) )
    {
        fprintf(stderr, "Eroare: nu pot crea un canal anonim, errno=%d\n",errno);  perror("Cauza erorii");  exit(1);
    }

    if(-1 == (pid=fork()) )
    {
        perror("Eroare: nu am putut crea un fiu. Cauza erorii");  exit(2);
    }

    if(pid == 0)
    {
        if(-1 == dup2(p[1],1) )
        {
            perror("Eroare: redirectarea iesirii standard in fiu a esuat. Cauza erorii");  exit(3);
        }

        execlp("tr", "tr", "-s", "\" \"", NULL);
        perror("Eroare la execlp() in fiu. Cauza erorii");  exit(4);
    }
    else
    {
        close(p[1]);

        if(-1 == dup2(p[0],0) )
        {
            perror("Eroare: redirectarea intrarii standard in parinte a esuat. Cauza erorii");  exit(5);
        }

        execl("cv1.3.exe","cv1.3",NULL);
        perror("Eroare la execl() in parinte. Cauza erorii"); exit(6);

    }

    return 0;
}


----------------------------------------------------------------------
#fisierul cv1.3.c
----------------------------------------------------------------------

#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <errno.h>

int main()
{
    pid_t pid;
    int p[2];

    if(-1 == pipe(p) )
    {
        fprintf(stderr, "Eroare: nu pot crea un canal anonim, errno=%d\n",errno);  perror("Cauza erorii");  exit(1);
    }

    if(-1 == (pid=fork()) )
    {
        perror("Eroare: nu am putut crea un fiu. Cauza erorii");  exit(2);
    }

    if(pid == 0)
    {
        if(-1 == dup2(p[1],1) )
        {
            perror("Eroare: redirectarea iesirii standard in fiu a esuat. Cauza erorii");  exit(3);
        }

        execlp("cut", "cut", "-d\" \"", "-f1,8", NULL);
        perror("Eroare la execlp() in fiu. Cauza erorii");  exit(4);
    }
    else
    {
        close(p[1]);

        if(-1 == dup2(p[0],0) )
        {
            perror("Eroare: redirectarea intrarii standard in parinte a esuat. Cauza erorii");  exit(5);
        }

        execlp("sort","sort","-t", "\" \"", "-k","1", NULL);
        perror("Eroare la execlp() in parinte. Cauza erorii");  exit(6);
    }

    return 0;
}