[Overview][Constants][Types][Procedures and functions][Variables][Index] Reference for unit 'Unix' (#rtl)

AssignStream

Assign stream for in and output to a program

Declaration

Source position: unix.pp line 112

function AssignStream(

var StreamIn: text;

var Streamout: text;

const Prog: ansiString;

const args: array of ansistring

):cint ; function AssignStream(

var StreamIn: text;

var Streamout: text;

var streamerr: text;

const Prog: ansiString;

const args: array of ansistring

):cint ;

Description

AssignStream creates a 2 or 3 pipes, i.e. two (or three) file objects, one for input, one for output,(and one for standard error) the other ends of these pipes are connected to standard input and output (and standard error) of Prog. Prog is the path of a program (including path). The options for the program can be specified in Args.

What is written to StreamOut, will go to the standard input of Prog. Whatever is written by Prog to it's standard output can be read from StreamIn. Whatever is written by Prog to it's standard error read from StreamErr, if present.

Reading and writing happens through the usual Readln(StreamIn,...) and Writeln (StreamOut,...) procedures.

Remark: You should not use Reset or Rewrite on a file opened with POpen. This will close the file before re-opening it again, thereby closing the connection with the program.

The function returns the process ID of the spawned process, or -1 in case of error.

Errors

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.

Other errors include the ones by the fork and exec programs

Example

Program Example38;
{ Program to demonstrate the AssignStream function. }
Uses BaseUnix,Unix;
Var Si,So : Text;
 S : String;
 i : longint;
begin
 if not (paramstr(1)='-son') then
 begin
 Writeln ('Calling son');
 Assignstream (Si,So,paramstr(0),['-son']);
 if fpgeterrno<>0 then
 begin
 writeln ('AssignStream failed !');
 halt(1);
 end;
 Writeln ('Speaking to son');
 For i:=1 to 10 do
 begin
 writeln (so,'Hello son !');
 if ioresult<>0 then writeln ('Can''t speak to son...');
 end;
 For i:=1 to 3 do writeln (so,'Hello chap !');
 close (so);
 while not eof(si) do
 begin
 readln (si,s);
 writeln ('Father: Son said : ',S);
 end;
 Writeln ('Stopped conversation');
 Close (Si);
 Writeln ('Put down phone');
 end
 Else
 begin
 Writeln ('This is the son ');
 While not eof (input) do
 begin
 readln (s);
 if pos ('Hello son !',S)<>0 then
 Writeln ('Hello Dad !')
 else
 writeln ('Who are you ?');
 end;
 close (output);
 end
end.

Documentation generated on: May 14 2021

AssignStream

Declaration

Description

Errors

See also

Example