WRITEPIPELINES(3A)                             WRITEPIPELINES(3A)



  NAME
       WritePipeLines, WritePipeLinesV - asynchronously write lines
       of data to a pipe


  SYNOPSIS
       WritePipeLines (line, ready, error, arg, cmd, arg ...)
       int (*line)();
       int (*ready)();
       char *(*error)();
       int arg;
       char *cmd;
       char *arg;

       WritePipeLinesV (line, ready, error, arg, cmd, argv)
       int (*line)();
       int (*ready)();
       char *(*error)();
       int arg;
       char *cmd;
       char *argv;

  DESCRIPTION
       WritePipeLines and WritePipeLinesV write lines of data to a
       command.  A command is executed with its standard input file
       redirected to a pipe.  The full path name of the command to
       execute is in cmd.  For WritePipeLines , arguments for the
       command (starting with arg as argument zero) follow the
       command in a NULL terminated parameter list.  For
       WritePipeLinesV , the arguments are in the NULL-terminated
       array of strings argv.  The function line is called to
       obtain each line to write, the function ready is called
       after the file has been closed, and the function error is
       called upon an error.  Any function may be NULL, in which
       case it will not be called.  When there is an error, the
       pipe is closed, so exactly one of the two functions ready
       and error is called.  The argument arg is passed to both
       routines.

       The calling sequence for line is as follows:


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  WRITEPIPELINES(3A)                             WRITEPIPELINES(3A)



            char *line (arg, error, buf, length)
            int arg;
            int error;
            char *buf;
            int length;

       The user-supplied argument to WritePipeLines or
       WritePipeLinesV is in arg.  The error code, error, is always
       zero.  The line and its length are in buf and length.  The
       length includes the terminating newline, but not the zero
       byte.  The line function returns a buffer for the next line
       or NULL.  The file will be closed if NULL is returned,
       causing the ready function to be called.  The buffer may be
       the same address passed by the parameter buf, or it may be
       another malloced area of at least BUFSIZ bytes.  The
       application is responsible for freeing the buffer, sometime
       after the next call to one of the line or ready functions.

       The calling sequence for ready is as follows:

            ready (arg, status)
            int arg;
            int status;

       The first argument arg is the argument supplied to
       WritePipeLines or WritePipeLinesV.  The child's exit status
       is in status.

       The calling sequence for error is as follows:

            error (arg, errno)
            int arg;
            int errno;

       The user-supplied data to WritePipeLines or WritePipeLinesV
       is passed in arg and an error code interpreted the same as
       the system global variable errno is passed in errno .

       WritePipeLines and WritePipeLinesV return the process ID of
       the child process on success, or -1 upon error.


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  WRITEPIPELINES(3A)                             WRITEPIPELINES(3A)



  NOTES
       There are lower-level asynchronous I/O routines AddIoProc,
       RemoveIoProc, OpenWritePipe, and ClosePipe that provide
       greater flexibility at the expense of greater coding effort.
       WritePipeLines and WritePipeLinesV use these routines to set
       up an asynchronous write procedure.

  SEE ALSO
       XtAppAddInput(3Xt), XtRemoveInput(3Xt), AddIoProc(3A),
       RemoveIoProc(3A), OpenWritePipe(3A), ClosePipe(3A),
       ReadFileData(3A), ReadFileLines(3A), ReadFileStrings(3A),
       ReadPipeData(3A), ReadPipeLines(3A), ReadPipeStrings(3A),
       WriteFileData(3A), WriteFileLines(3A), WritePipeData(3A)





























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