Force batch file to wait for his own process - batch-file

Question

I would like to force command line to wait for his own process, because this process app.exe must finish, and takes some time. I use artificial timeout to prevent script from closing, because if I set the timeout wrong, then app.exe gives wrong results. I have problem with correct estimate timeout.
I read something about options /w and /k but I don't know where it insert.
Maybe wait for process would be good solution, but I don't know how can I do it.
Code is below:
(
#echo instruction1 to app.exe
#echo instruction2 to app.exe
#echo instruction3 to app.exe
#echo instruction4 to app.exe
timeout 3
) | app.exe > out.txt
This script is called from another application written in c++ but not from app.exe. I have windows 7.
The line which run script:
system("script.bat");

Answer 1

you may use start command to make a batch script wait for itself
#echo off
if /I "%~1" EQU "runme" goto %~1
start "" /B /WAIT cmd /c "%~s0 runme %*"
exit /B
:runme
(
#echo instruction1 to app.exe
#echo instruction2 to app.exe
#echo instruction3 to app.exe
#echo instruction4 to app.exe
) | app.exe > out.txt
timeout 3
exit /B
EDIT: may I misunderstood your question, perhaps this is what you're asking for
start "" /B /WAIT cmd /c "app.exe some_parameter_here"
start "" /B /WAIT cmd /c "app.exe some_parameter_here"
start "" /B /WAIT cmd /c "app.exe some_parameter_here"
...
or
start "" /B /WAIT cmd /c "echo some_parameter_here | app.exe"
start "" /B /WAIT cmd /c "echo some_parameter_here | app.exe"
start "" /B /WAIT cmd /c "echo some_parameter_here | app.exe"
...