AssignPipe
Create a set of pipe file handlers
Declaration
Source position: unix.pp line 135
function AssignPipe(var pipe_in: cint; var pipe_out: cint) : cint;
function AssignPipe(var pipe_in: text; var pipe_out: text) : cint;
function AssignPipe(var pipe_in: File; var pipe_out: File) : cint;
Description
AssignePipe creates a pipe, i.e. two file objects, one for input, one for output. What is written to Pipe_out, can be read from Pipe_in.
This call is overloaded. The in and out pipe can take three forms: an typed or untyped file, a text file or a file descriptor.
If a text file is passed then reading and writing from/to the pipe can be done through the usual Readln(Pipe_in,...) and Writeln(Pipe_out,...) procedures.
The function returns True if everything went successfully, False otherwise.
Errors
In case the function fails and returns False, extended error information is returned by the FpGetErrno function:
- sys_emfile
- Too many file descriptors for this process.
- sys_enfile
- The system file table is full.
See also
| Name | Description |
|---|---|
| POpen | Pipe file to standard input/output of program |
| #rtl.baseunix.FpMkFifo | Create FIFO (named pipe) in file system |
Example
Program Example36;
{ Program to demonstrate the AssignPipe function. }
Uses BaseUnix,Unix;
Var pipi,pipo : Text;
s : String;
begin
Writeln ('Assigning Pipes.');
If assignpipe(pipi,pipo)<>0 then
Writeln('Error assigning pipes !',fpgeterrno);
Writeln ('Writing to pipe, and flushing.');
Writeln (pipo,'This is a textstring');close(pipo);
Writeln ('Reading from pipe.');
While not eof(pipi) do
begin
Readln (pipi,s);
Writeln ('Read from pipe : ',s);
end;
close (pipi);
writeln ('Closed pipes.');
writeln
end.