Pascal library for running processes and redirecting their output.
There are other pascal components for running processess and redirect their output. This library is the outcome of frustrations with most of those components:
- Fixation with and premature conversion to strings. Processes produce and consume bytes.
- Blocking reading of process output, resulting to inefficiencies (tight loops with Sleep, or separate threads for reading the output or providing input to the process)
- Incomplete features and/or over-bloated
- Multi-platform support. Works with all desktop Delphi compilers (WINDOWS, LINUX, MACOS)
- Asynchronous reading of process output
- Separate stdout and stderr reading which can optionally be merged
- Ability to consume output as it is produced or else let it accumulate and read the final result
- Ability to provide input to the running process before or while the process is running.
- Ability to terminate the running process.
- Synchronous and asynchronous execution of processes.
- Interfaced-based facilitating memory management.
You do not need to install the library. Just download or clone this repo and add the source subdirectory to the Library path.
This is a single unit library. Add PascalProcess to your uses clause.
If you just want to get the output of a process you can use the class functions of TPProcess.
TPProcess = class(TInterfacedObject, IPProcess)
class function Execute(const ACommandLine: string;
const ACurrentDir: string = ''): TBytes; overload;
class procedure Execute(const ACommandLine: string;
const ACurrentDir: string; out Output, ErrOutput: TBytes) overload;
end;This is an example:
var
Output: TBytes;
begin
Output := TPProcess.Execute('cmd /c echo Hi');
Writeln(TEncoding.Default.GetString(Output));
end;For more demanding cases you can use the IPProcess interface.
Example:
type
TUtils = class
class procedure OnRead(Sender: TObject; const Bytes: TBytes; BytesRead: Cardinal);
end;
{ TUtils }
class procedure TUtils.OnRead(Sender: TObject; const Bytes: TBytes; BytesRead: Cardinal);
begin
Writeln(TEncoding.Default.GetString(Bytes, 0, BytesRead));
end;
procedure Test2;
// Processes ouput as it gets produced
// The main thread terminates the process
var
Process: IPProcess;
begin
Process := TPProcess.Create('cmd /c dir c:\ /s');
Process.OnRead := TUtils.OnRead;
WriteLn('Press Enter to start the process. Press Enter again to terminate');
ReadLn;
Process.Execute;
ReadLn;
Process.Terminate;
end;See here the definition of IPProcess.