node.jslogginginstallationinno-setuppascalscript

How to append new content in existing text file in Inno Setup

I have enabled the installation log in Inno Setup using SetupLogging = yes.

It is creating a log file temp directory and I'm copying that log to my program data:

procedure DeinitializeSetup();    
var  
  logfilepathname, newfilepathname: string;  
begin  
  logfilepathname := ExpandConstant('{log}');  
  newfilepathname := 'ProgramData\InstallerlogFile'
 
  FileCopy(logfilepathname, newfilepathname, false);  
end;

Every time I create a new installer it replaces the content of the older file in program data. I wanted to append new log content instead of replacing it.

Solution

  • The easiest way to append not-too-huge contents from one file to another is using LoadStringFromFile and SaveStringToFile:

    var
  S: AnsiString;
begin
  if LoadStringFromFile(logfilepathname, S) then
    SaveStringToFile(newfilepathname, S, True); // True = append
end;

    Or you can just execute copy "cmd" command using Exec, when "dest" exists already (if not, use your FileCopy code):

    copy [/b] <dest> + <source>

    But that won't work for the log, as it is locked by the installer proces. To read a locked file, you need to resort to more low-level functions. You can use TFileStream with its fmShareDenyNone.

    For an example, see FileCopyUnrestricted in my answer to
    How can I copy the installer to the temp file and then run it?

    To make it append, replace the

    Stream := TFileStream.Create(NewFile, fmCreate);

    with

    if not FileExists(NewFile) then Mode := fmCreate
  else Mode := fmOpenWrite;
Stream := TFileStream.Create(NewFile, Mode);
Stream.Seek(0, soFromEnd);