p2open(3GEN)					     String Pattern-Matching Library Functions					      p2open(3GEN)

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

       The  p2open()gfunction  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.

       The  p2close()  function  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.

RETURN VALUES

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

EXAMPLES

       Example 1 Example of file descriptors.

	 #include <stdio.h>
	 #include <libgen.h>

	 main(argc,argv)
	 int argc;
	 char **argv;
	 {
	      FILE *fp[2];
	      pid_t pid;
	      char buf[16];

		 pid=p2open("/usr/bin/cat", fp);
		 if ( pid == -1 ) {
		   fprintf(stderr, "p2open failed
");
		   exit(1);
	      }
	      write(fileno(fp[0]),"This is a test
", 16);
	      if(read(fileno(fp[1]), buf, 16) <=0)
		   fprintf(stderr, "p2open failed
");
	      else
		   write(1, buf, 16);
	      (void)p2close(fp);
	 }

ATTRIBUTES

       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |MT-Level		     |Unsafe			   |
       +-----------------------------+-----------------------------+

SEE ALSO

       fclose(3C), popen(3C), setbuf(3C), attributes(5)

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(3C).

       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.

SunOS 5.11							    29 Dec 1996 						      p2open(3GEN)