http://publib.boulder.ibm.com/infocenter/zos/v1r12/index.jsp?topic=%2Fcom.ibm.zos.r12.cbcpx01%2Ffifopip.htm

Pipes.c

/* this example shows how named pipes may be used */
#define _OPEN_SYS
#include <stdio.h>
#include <unistd.h>
#include <errno.h>
#include <fcntl.h>
#include <sys/wait.h>
/*                                                                *
 *   Sample use of mkfifo()                                       *
 *                                                                */

main()
{
    /* start of program          */
    int     flags, ret_value, c_status;
    pid_t   pid;
    size_t  n_elements;
    char    char_ptr[32];
    char    str[] = "string for fifo ";
    char    fifoname[] = "temp.fifo";
    FILE    *rd_stream,*wr_stream;

    if ((mkfifo(fifoname,S_IRWXU)) != 0) {
        printf("Unable to create a fifo; errno=%d\n",errno);
        exit(1);
        /* Print error message and return */
    }

    if ((pid = fork()) < 0) {
        perror("fork failed");
        exit(2);
    }

    if (pid == (pid_t)0) {
        /* CHILD process                  */
        /* issue fopen for write end of the fifo                     */
        wr_stream = fopen(fifoname,"w");

        if (wr_stream == (FILE *) NULL)  {
            printf("In child process\n");
            printf("fopen returned a NULL, expected valid stream\n");
            exit(100);
        }

        /* perform a write                                        */
        n_elements = fwrite(str,1,strlen(str),wr_stream);
        if (n_elements != (size_t) strlen(str)) {
            printf("Fwrite returned %d, expected %d\n",
                   (int)n_elements,strlen(str));
            exit(101);
        }

        exit(0);
        /* return success to parent        */
    } else {
        /* PARENT  process                 */
        /* issue fopen for read            */
        rd_stream = fopen(fifoname,"r");
        if (rd_stream == (FILE *) NULL)  {
            printf("In parent process\n");
            printf("fopen returned a NULL, expected valid pointer\n");
            exit(2);
        }

        /* get current flag settings of file                      */
        if ((flags = fcntl(fileno(rd_stream),F_GETFL)) == -1) {
            printf("fcntl returned -1 for %s\n",fifoname);
            exit(3);
        }

        /* clear O_NONBLOCK  and reset file flags                 */
        flags &= (O_NONBLOCK);
        if ((fcntl(fileno(rd_stream),F_SETFL,flags)) == -1) {
            printf("\nfcntl returned -1 for %s",fifoname);
            exit(4);
        }

        /* try to read the string                              */
        ret_value = fread(char_ptr,sizeof(char),strlen(str),rd_stream);
        if (ret_value != strlen(str)) {
            printf("\nFread did not read %d elements as expected ",
                   strlen(str));
            printf("\nret_value is %d ",ret_value);
            exit(6);
        }

        if (strncmp(char_ptr,str,strlen(str))) {
            printf("\ncontents of char_ptr are %s ",
                   char_ptr);
            printf("\ncontents of str are %s ",
                   str);
            printf("\nThese should be equal");
            exit(7);
        }

        ret_value = fclose(rd_stream);
        if (ret_value != 0)  {
            printf("\nFclose failed for %s",fifoname);
            printf("\nerrno is %d",errno);
            exit(8);
        }

        ret_value = remove(fifoname);
        if (ret_value != 0)  {
            printf("\nremove failed for %s",fifoname);
            printf("\nerrno is %d",errno);
            exit(9);
        }

        pid = wait(c_status);
        if ((WIFEXITED(c_status) !=0) &&; (WEXITSTATUS(c_status) !=0)) {
            printf("\nchild exited with code %d",WEXITSTATUS(c_status));
            exit(10);
        }
    }
    /* end of else clause                                       */
    printf("About to issue exit(0),  \
processing completed successfully\n");
    exit(0);
}