Windows Overwriting console - console

Question

I was downloading MingW, and noticed that for a time the installer spawns a console window and downloads files. The intersting part is that it somehow creates download bars in the console window and overwrites the precentage number. I was wondering how this is accomplished?
NOTE:I am almost 100% sure the console is not writing '\n' out and is in fact overwriting the console.

Answer 1

I see Google was broken.
http://ss64.org/viewtopic.php?id=1499
The code:
#echo off
:: *****************************************************************************
:: * Script Name: DetectMSI_v1.0.cmd *
:: * Author: Gustaaf von Pickartz. *
:: * Date Created: 19th July, 2012. *
:: * Internal Version: Version 1.0 *
:: * ------------------------------------------------------------------------- *
:: * Notice: *
:: * This program is provided as is and for fair use distribution. *
:: * Give credit where credit is due to the author in your own script. *
:: * ------------------------------------------------------------------------- *
:: * Purpose: *
:: * Detect current active MSIEXEC instances using a function for repeatable *
:: * calls within a script and display a progress bar... *
:: * ------------------------------------------------------------------------- *
:: * Updated by: ------- *
:: * Date: 19-07-2012 *
:: * Change1: "Initial script version." *
:: * ------------------------------------------------------------------------- *
:: *****************************************************************************
SETLOCAL ENABLEDELAYEDEXPANSION
SET PRG0=[* ]
SET PRG1=[#* ]
SET PRG2=[##* ]
SET PRG3=[###* ]
SET PRG4=[####* ]
SET PRG5=[#####* ]
SET PRG6=[######* ]
SET PRG7=[#######* ]
SET PRG8=[########* ]
SET PRG9=[#########*]
SET PRG10=[##########]
:: Please note there are special ASCII insertions in the SET BKSPC= declaration below. 80x backspace characters are inserted. ASCII Value 08=[BS]
:: Be sure to verify they are still there when you cut and paste from the web with your text editor (Notepad++ or PsPad). Insert them if missing, otherwise this script will not work...
SET BKSPC=
:Begin_Main
:: For the sake of the demonstration, start MSIEXEC minimized.
START /MIN MSIEXEC
:: Call our function.
CALL :Fnc_Msi
:: Waste a little time...
PING -n 7 localhost >nul
ECHO Exited the FIRST MSIEXEC detection function and progress bar demo.
ECHO.
ECHO.
ECHO A function can't be a function if it cannot be re-used right?
:: For the sake of the demonstration, start MSIEXEC minimized.
START /MIN MSIEXEC
:: Call our function.
CALL :Fnc_Msi
ECHO Exited the SECOND MSIEXEC detection function and progress bar demo.
echo.
echo.
pause
GOTO :EOF
:: -----------------------------------------------------------------------------
:: Below code is setup to run as a Function to be called anywhere in your script.
:: It will wait 10 loops at 7 sec intervals anytime it is called. Primarily written to detect active MSI installers.
:: The Menu counter and Progress bar is in the function for fun.
::
:: Usage: CALL :Fnc_Msi
2
:Fnc_Msi
CALL ECHO [.....] %%date%% %%time%% Testing for active MSI instances.
:catchit
IF NOT DEFINED CatchMSI SET CatchMSI=0
IF %CatchMSI% EQU 5 (
ECHO Waited 5 loops {15sec.} to detect MSI activities. Now resuming further MSI evaluation.
goto evalmsi
)
FOR /F "TOKENS=2* DELIMS=:" %%I IN ('TASKLIST /V /FI "IMAGENAME EQ MSIEXEC.EXE" /FO LIST 2^>NUL ^|FIND /I /V "N/A" ^|FIND /I "WINDOW TITLE:"') DO (SET MSI=%%I)
IF DEFINED MSI SET MSI_APP=%MSI:~1%
IF DEFINED MSI_APP goto msi_active
>NUL PING -n 3 localhost
SET /A CatchMSI+=1
goto :catchit
:evalmsi
IF NOT DEFINED MSI_APP (
ECHO [OKAY.] No active MSIEXEC installer running. It is safe to continue.
SET CatchMSI=
SET MSI_APP=
SET CNT=
SET COUNT=
SET TIC=
GOTO :EOF
)
:msi_active
SET CNT=0
ECHO [ALERT] Installer "%MSI_APP%" is active. Waiting maximum 10 counts.
:loop
IF NOT DEFINED COUNT SET COUNT=0
IF %COUNT% LEQ 9 (SET TIC=0%COUNT%) ELSE (SET TIC=%COUNT%)
IF %count% EQU 10 (
<NUL (SET/P Z=[%tic%/10] PROGRESS: !PRG%CNT%!)
:: Feel free to adjust the PING -n 3 value to say 30sec waits.
>NUL PING -n 3 localhost
TASKKILL /F /FI "WINDOWTITLE eq %MSI_APP%*" >>myprogress.log
<NUL SET/P Z=%BKSPC%
SET MSI_APP=
SET CatchMSI=
SET MSI_APP=
SET CNT=
SET COUNT=
SET TIC=
GOTO :EOF
)
<NUL (SET/P Z=[%tic%/10] PROGRESS: !PRG%CNT%!)
:: Feel free to adjust the PING -n 3 value to say 30sec waits.
>NUL PING -n 3 localhost
<NUL SET/P Z=%BKSPC%
:: Here we write to a log file and call tasklist.exe to do interval checks on the MSIEXEC status.
:: Demonstrated is that the progress bar is not affected when code is run in the loop.
:: Do keep in mind to "suppress to >nul 2>nul" any output that may disrupt the progress bar activty.
ECHO [%tic%/10] Waiting for "%MSI_APP%" to complete. >>myprogress.log
TASKLIST.EXE /V | FIND /I "%MSI_APP%">NUL 2>NUL
IF %ERRORLEVEL% EQU 1 (
>NUL PING -n 7 localhost
SET CatchMSI=
SET MSI_APP=
SET CNT=
SET COUNT=
SET TIC=
GOTO :EOF
)
SET /A CNT+=1
SET /A COUNT+=1
goto loop
GOTO :EOF
:: -----------------------------------------------------------------------------
Credit is obviously due to the original author.