p2open(3G)                        SDK R4.11                       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).

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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