Console App: pipe | to stdin of my app
lazarus / 34-Windows

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Stefan · 2014-05-25 10:42

Hello community.

I am Stefan, I am new to Pascal but have some knowledge with VBS, JS,
PascalScript, Batch,...


Now I wrote my first console application with fpc-2.6.4.i386-win32 on
W7-32.

Every thing works fine so far, but I can't find an answer about this
question:

How can I get input at stdin from piped output, of lets say 'DIR /B
/S' ?

Something :
C:\Temp\>DIR /B | sed -e "///"

Currently I utilize only ParamCount and ParamStr().

How can I get piped-in data on stdin?
C:\Temp\>DIR /B | myapp.exe

My current code (partially excerpt):
Code: [Select]var

begin
    if(ParamCount > 1) Then
    begin
        sInputArg   := ParamStr(1);
        sOutputStr := StringReplace( sInputArg ,  sBefore, sAfter,
[rfReplaceAll]);
    end;
    WriteLn(sOutputStr);
end.

Usage:
c:\FPC\2.6.4\demo\text>for /F "tokens=*" %a in ('dir /B') do
@myapp.exe "%a"

That works fine, but,


Wanted usage:
c:\FPC\2.6.4\demo\text>dir /B | myapp.exe

Pascal code for this wanted usage:
??? need your help here please !

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Leledumbo · 2014-05-25 11:20

Piped input is read from standard input, so use Read(Ln) for that.

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Stefan · 2014-05-25 11:50

Thank you very much. But I only get the first arg/filename piped. All
the others are not printed.


How can I manage to execute my app for each piped filename?

So far I have:
Code: [Select]program Hello;

{$APPTYPE CONSOLE}
 
uses
  SysUtils, StrUtils;

var
  sInputArg, sOutputStr, sBefore, sAfter : WideString;

begin
ReadLn(sInputArg);
  if not (sInputArg = '') Then
  //while not (sInputArg = '') do
  begin
    sBefore := 'A';
    sAfter  := 'X';
    sOutputStr := StringReplace(sInputArg,  sBefore, sAfter,
[rfReplaceAll]);
    WriteLn(sOutputStr);
    sInputArg := '';
  end;
end.

Thank you in advance.

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Stefan · 2014-05-25 11:57

I think I found it:

Code: [Select]begin
  Repeat
      ReadLn(sInputArg);
        sBefore := 'e';
        sAfter  := 'X';
        sOutputStr := StringReplace(sInputArg,  sBefore, sAfter,
[rfReplaceAll]);
        WriteLn(sOutputStr);
  Until sInputArg = '';
end.
.

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Leledumbo · 2014-05-25 12:00

better use:
Code: [Select]while not EOF do begin
  ReadLn(YourVar);
  ... // process YourVar here
end;

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Stefan · 2014-05-25 16:36

Thanks, solved.