Provided by: ltp-dev_20091231+dfsg-1ubuntu2_amd64 bug

NAME

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

SYNOPSIS

       int
       background(prefix)
       char *prefix;

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

       extern int Forker_pids[];
       extern int Forker_npids;

DESCRIPTION

       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 printed.

EXAMPLES

          /*
           * 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]);
                  exit(1);
              }

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

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

              printf("Starting Pid = %d0, getpid());
              ret=background(argv[0]);
              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());
              sleep(30);
              exit(0);
          }

SEE ALSO

       fork(2).

BUGS

       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.