p2open(3G)                       UNIX System V                       p2open(3G)


NAME
      p2open, p2close - open, close pipes to and from a command

SYNOPSIS
      cc [flag ...] file ...  -lgen [library ...]

      #include <libgen.h>

      int p2open (const char *cmd, FILE *fp[2]);

      int p2close (FILE *fp[2]);

DESCRIPTION
      p2open forks and execs a shell running the command line pointed to by
      cmd.  On return, fp[0] points to a FILE pointer to write the command's
      standard input and fp[1] points to a FILE pointer to read from the
      command's standard output.  In this way the program has control over the
      input and output of the command.

      The function returns 0 if successful; otherwise it returns -1.

      p2close is used to close the file pointers that p2open opened.  It waits
      for the process to terminate and returns the process status.  It returns
      0 if successful; otherwise it returns -1.

EXAMPLES
      #include <stdio.h>
      #include <libgen.h>
      main(argc,argv)
      int argc;
      char **argv;
      {
            FILE *fp[2];
            pidt pid;
            char buf[16];
            pid=p2open("/usr/bin/cat", fp);
            if ( pid == 0 ) {
                  fprintf(stderr, "p2open failed\n");
                  exit(1);
            }
            write(fileno(fp[0]),"This is a test\n", 16);
            if(read(fileno(fp[1]), buf, 16) <=0)
                  fprintf(stderr, "p2open failed\n");
            else
                  write(1, buf, 16);
            (void)p2close(fp);
      }

SEE ALSO
      fclose(3S), popen(3S), setbuf(3S).




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p2open(3G)                       UNIX System V                       p2open(3G)


DIAGNOSTICS
      A common problem is having too few file descriptors.  p2close returns -1
      if the two file pointers are not from the same p2open.

NOTES
      Buffered writes on fp[0] can make it appear that the command is not
      listening.  Judiciously placed fflush calls or unbuffering fp[0] can be a
      big help; see fclose(3S).

      Many commands use buffered output when connected to a pipe.  That, too,
      can make it appear as if things are not working.

      Usage is not the same as for popen, although it is closely related.









































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