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       forker - fork desired number of copies of the current process
       background - fork a process and return control to caller


       char *prefix;

       forker(ncopies, mode, prefix)
       int ncopies;
       int mode;
       char *prefix;

       extern int Forker_pids[];
       extern int Forker_npids;


       The  background  function  will  do a fork of the current process.  The
       parent process will then exit, thus orphaning the child process.  Doing
       this  will  not  nice  the  child  process  like executing a cmd in the
       background using "&" from the shell.  If the fork fails and  prefix  is
       not  NULL,  a  error  message is printed to stderr and the process will
       exit with a value of errno.

       The forker function will fork ncopies minus one copies of  the  current
       process.   There  are  two modes in how the forks will be done.  Mode 0
       (default) will have  all  new  processes  be  children  of  the  parent
       process.     Using  Mode  1, the parent process will have one child and
       that child will fork the next process, if necessary,  and  on  and  on.
       The  forker  function will return the number of successful forks.  This
       value will be different for the parent and each child.  Using  mode  0,
       the  parent  will get the total number of successful forks.  Using mode
       1, the newest child will get the total number  of  forks.   The  parent
       will get a return value of 1.

       The forker function also updates the global variables Forker_pids[] and
       Forker_npids.  The Forker_pids array will be updated to contain the pid
       of  each new process.  The Forker_npids variable contains the number of
       entries in Forker_pids.  Note, not all processes will  have  access  to
       all  pids  via  Forker_pids.   If using mode 0, only the parent process
       will have all information.  If  using  mode  1,  only  the  last  child
       process will have all information.

       If  the  prefix parameter is not NULL and the fork system call fails, a
       error message will be printed to stderr.  The  error  message  will  be
       preceded  with  prefix  string.  If prefix is NULL, no error message is


           * The following is a unit test main for the background and forker
           * functions.

          #include <stdio.h>

          main(argc, argv)
          int argc;
          char **argv;
              int ncopies=1;
              int mode=0;
              int ret;

              if ( argc == 1 ) {
                  printf("Usage: %s ncopies [mode]0, argv[0]);

              if ( sscanf(argv[1], "%i", &ncopies) != 1 ) {
                  printf("%s: ncopies argument must be integer0, argv[0]);

              if ( argc == 3 )
                  if ( sscanf(argv[2], "%i", &mode) != 1 ) {
                  printf("%s: mode argument must be integer0, argv[0]);

              printf("Starting Pid = %d0, getpid());
              printf("After background() ret:%d, pid = %d0, ret, getpid());

              ret=forker(ncopies, mode, argv[0]);

              printf("forker(%d, %d, %s) ret:%d, pid = %d, sleeping 30 seconds.0,
                  ncopies, mode, argv[0], ret, getpid());




       The child pids are stored in the fixed array, Forker_pids.   The  array
       only  has space for 4098 pids.  Only the first 4098 pids will be stored
       in the array.